ML23331A979
| ML23331A979 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 11/27/2023 |
| From: | Miami Waterkeeper |
| To: | NRC/SECY/RAS |
| SECY RAS | |
| References | |
| RAS 56848, 50-250-SLR-2, 50-251-SLR-2 | |
| Download: ML23331A979 (0) | |
Text
EXHIBIT 16
Miami Cave Crayfish (Procambarus milleri)
Species Status Assessment Version 1.0 1-10-2022 U.S. Fish and Wildlife Service South Atlantic-Gulf Region Atlanta, GA Exhibit 16
ii ACKNOWLEDGEMENTS This document was prepared by the Miami Cave Crayfish Core Team: Emily Bauer (USFWS -
Florida Field Office), Bonnie Gulas-Wroblewski (Texas A&M Natural Resources Institute),
Charles Herrmann (USFWS - HQ), and Michael Marshall (Texas A&M Natural Resources Institute). William Loftus (Aquatic Research & Communication, LLC) was enthusiastic and supportive in his sharing of valuable insight on the species and habitat. Technical assistance was also provided by Ryan Boyles (Southeast Climate Adaptation Science Center, USGS), Lorna Bucknor (Miami-Dade County), Lisa Krimsky (Tropical Research and Education Center, University of Florida), Bruce Schaffer (Tropical Research and Education Center, University of Florida), Ashley Smyth (Tropical Research and Education Center, University of Florida).
Unpublished data was shared by William Loftus, David Cook (Florida Fish and Wildlife Conservation Commission), Paul Moler (Florida Fish and Wildlife Conservation Commission),
Adam Stern (Cutler Bay, Florida), and Heather Bracken-Grissom (Florida International University).
Valuable peer reviews of a draft of this document were provided by William Loftus, Adam Stern (Zoo Miami), and Maria Cristina Bruno (Fondazione Edmund Mach, Research and Innovation Centre).
We appreciate the time and effort of those dedicated to learning and implementing the SSA Framework, which resulted in a more robust assessment and final report.
Suggested reference:
U.S. Fish and Wildlife Service. 2022. Species status assessment report for the Miami Cave Crayfish (Procambarus milleri). Version 1.0. January 10, 2022. Atlanta, GA.
Exhibit 16
iii EXECUTIVE
SUMMARY
This report summarizes the results of a species status assessment (SSA) conducted for the Miami cave crayfish (Procambarus (Leconticambarus) milleri), a species petitioned in 2010 for listing under the Endangered Species Act of 1973, as amended (Act). The SSA assesses (chapter 1) the species viability by characterizing the biological status of the species in terms of its resiliency, redundancy, and representation (together, the 3Rs). For the purpose of this assessment, we generally define viability as the ability of the species to sustain populations in natural ecosystems within a biologically meaningful timeframe, in this case 50 years. In conducting the SSA, we compiled the best available scientific information regarding the Miami cave crayfishs biology (chapter 2); individual-, population-, and species-level needs (chapter 2); and factors that influence the species viability (chapter 3). We use this information to evaluate and describe the species current (chapter 4) and projected future conditions (chapter 5) in terms of the 3Rs. This SSA does not represent a decision by the Service whether or not to list a species under the Act.
Instead, this SSA provides a review of the best available information strictly related to the biological status of the Miami cave crayfish. The listing decision will be made by the Service after reviewing this document and all relevant laws, regulations, and policies, and a decision will be announced in the Federal Register.
The Miami cave crayfish is a relatively small, freshwater, subterranean crustacean endemic to southern and central Miami-Dade County, Florida. The species has recently adapted to the belowground aquifer environment as is indicated by the presence of both pigment and eye facets in some individuals. The species has been collected from wells 7.9-36 ft (2.41-11 m) deep in the Miami Limestone and Fort Thompson limestone formation within the Biscayne Aquifer along the Atlantic Coastal Ridge in southern and central Miami-Dade County, Florida. Hobbs first described the species based on specimens collected south of Miami in 1968. Additional confirmed reports of the species followed in 1992, 2000-2004, 2009, and most recently in 2018.
Despite significant sampling effort, no specimens have been recovered from groundwater wells of similar depths within Everglades National Park, even those sampled along the western-most, isolated segment of the Atlantic Coastal Ridge at Long Pine Key.
To evaluate the current and future viability of Miami cave crayfish, we assessed a range of conditions to allow us to consider the species resiliency, representation, and redundancy. For the purposes of this assessment, seven distinct analysis units were delineated using the primary canal systems that overlap the transverse glades cutting into the Atlantic Coastal Ridge (Figure ES1).
Exhibit 16
iv Figure ES1. Endemic range of Miami cave crayfish in Miami-Dade County, Florida. Boundaries of seven analysis units are outlined in black and labeled accordingly.
Resiliency, assessed at the population level, describes the ability of a species to withstand environmental stochasticity, periodic disturbances within the normal range of variation, and demographic stochasticity. A species requires multiple resilient populations distributed across its range to persist into the future and avoid extinction. A number of factors influence whether Miami cave crayfish will occupy available habitat and exhibit resiliency: freshwater availability; structural complexity and interconnectedness of aquifer-containing limestone deposits; influx of surficial detritus; and sufficient water quality. As a species, Miami cave crayfish has limited resiliency with all of its current analysis units exhibiting low resilience on the basis of the quantity and quality of these habitat factors within the species narrow endemic range (Table ES 1).
Redundancy reflects the ability of a species to withstand natural or anthropogenic catastrophic events and is best achieved by having multiple, widely distributed populations relative to the spatial occurrence of catastrophic events. Catastrophic events are likely to concurrently affect all seven analysis units of Miami cave crayfish due to the restricted endemic range of the species and the high degree of connectivity of the Biscayne Aquifer system, especially on the Atlantic Coastal Ridge. Therefore, Miami cave crayfish was determined to have low redundancy.
Exhibit 16
v Representation (i.e., adaptive capacity) is the ability of a species to adapt to both near-term and long-term changes in its physical and biological environments. A species adaptive potential can be assessed by evaluating genetic, ecological, morphological, and/or behavioral variability. To date, intraspecific variation in genetic, morphologic, and/or ecological diversity has not been investigated in Miami cave crayfish. Therefore, based on the most current information available, we assessed the species as a single representative unit and determined Miami cave crayfish to have low representation.
To assess the condition of Miami cave crayfish 50 years into the future, a variety of influences, including aquifer drawdown, groundwater contamination, saltwater intrusion, loss of detrital input from surficial sources, and destruction of karstic limestone aquifer habitat, and their potential effects on population resiliency were considered. Populations with low resiliency are considered to be more vulnerable to extirpation, which, in turn, would decrease species level representation and redundancy. To help address uncertainty associated with the degree and extent of potential future influences and their impacts on species needs, the 3Rs were assessed using four plausible future scenarios (Table ES 1). These scenarios were based on each of three possible regional sea level rise scenarios (per Sweet et al. 2017, entire and Sweet et al. 2018, entire), variable levels of urbanization predicted by Florida 2070 (Carr and Zwick 2016, entire),
freshwater quality and quantity scenarios we defined for the Biscayne Aquifer, and four possible extensions of the saltwater interface within Miami-Dade County.
An important assumption of the predictive analysis was that future population resiliency is largely dependent on groundwater quality, freshwater availability, extent of karstic limestone habitat, and subterranean infiltration of surficial detritus. Our assessment predicted that all seven analysis units of Miami cave crayfish would experience negative changes to these habitat needs by 2070. Predicted viability for each scenario is summarized below in Table ES 1. Under each plausible future scenario, Miami cave crayfish exhibited reduced resiliency, representation, redundancy, and, thus, viability compared to its current condition.
Table ES 1. Summary results of the Miami cave crayfish Species Status Assessment.
The 3 Rs Needs Current Condition Future Condition (Viability)
Resiliency Freshwater availability (water quantity)
Sufficient water quality Food Availability Karstic limestone substrate with interconnected megaporosities All seven analysis units have low resiliency Projections based on development, regional sea level rise, anthropogenic water contamination, groundwater availability, and saltwater intrusion:
Scenario 1 (Continuation of Current Trends): All analysis units experience a decline in resiliency with one analysis unit extirpated.
Exhibit 16
vi Scenario 2 (Continuation of Current Trends with Moderate Increases in Aquifer Drawdown and Contamination): All analysis units experience a decline in resiliency with one analysis unit extirpated.
Scenario 3 (Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion):
All analysis units experience a drastic decline in resiliency with three analysis units extirpated.
Scenario 4 (Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise): All analysis units experience a decline in resiliency but remain extant.
Redundancy Multiple populations throughout the range of the species Highly restricted endemic range with all analysis units located proximate to one another High connectivity of Biscayne Aquifer system throughout endemic range Low redundancy Projections based on development, regional sea level rise, anthropogenic water contamination, groundwater availability, and saltwater intrusion:
Scenario 1 (Continuation of Current Trends):
Decline in redundancy with one analysis unit extirpated Scenario 2 (Continuation of Current Trends with Exhibit 16
vii Moderate Increases in Aquifer Drawdown and Contamination):
Decline in redundancy with one analysis unit extirpated Scenario 3 (Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion):
Drastic decline in redundancy with three analysis units extirpated Scenario 4 (Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise): Low redundancy approximating current condition Representation
- No information available to assess intraspecific diversity Assessed as single representative unit with low representation Projections based on development, regional sea level rise, anthropogenic water contamination, groundwater availability, and saltwater intrusion:
Scenario 1 (Continuation of Current Trends):
Decline in representation with one analysis unit extirpated Scenario 2 (Continuation of Current Trends with Moderate Increases in Aquifer Drawdown and Contamination):
Decline in representation with one analysis unit extirpated Exhibit 16
viii Scenario 3 (Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion):
Drastic decline in representation with three analysis units extirpated Scenario 4 (Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise): Low representation approximating current condition Exhibit 16
ix TABLE OF CONTENTS ACKNOWLEDGEMENTS............................................................................................................ ii EXECUTIVE
SUMMARY
........................................................................................................... iii CHAPTER 1 - INTRODUCTION.................................................................................................. 1 CHAPTER 2 - SPECIES BIOLOGY, LIFE HISTORY, AND NEEDS....................................... 3 2.1 Taxonomy and Evolutionary History.................................................................................... 3 2.2 Morphological Description................................................................................................... 4 2.3 Life History........................................................................................................................... 7 2.4 Other Pertinent Behaviors................................................................................................... 10 2.5 Habitat................................................................................................................................. 11 2.5.1 Biscayne Aquifer.......................................................................................................... 12 2.5.2 Atlantic Coastal Ridge.................................................................................................. 14 2.5.3 Hydrological Factors.................................................................................................... 18 2.5.4 Habitat Overview.......................................................................................................... 19 2.6 Historical and Current Range and Distribution................................................................... 19 2.7 Needs of the Miami Cave Crayfish..................................................................................... 23 2.7.1 Individual Needs........................................................................................................... 24 2.7.2. Population and Species Needs..................................................................................... 25 CHAPTER 3 - INFLUENCES ON VIABILITY......................................................................... 27 3.1 Modification of Surface Cover............................................................................................ 27 3.1.1 Development................................................................................................................. 27 3.1.2 Agriculture.................................................................................................................... 29 3.1.3 Anthropogenic Modification of Detrital Input............................................................. 33 3.1.4 Climate Change Effects................................................................................................ 35 3.1.5 Habitat Conservation.................................................................................................... 37 3.1.6 Summary of Modification of Surface Cover................................................................ 40 3.2 Modification of Karstic Limestone..................................................................................... 41 3.2.1 Subterranean Infrastructure.......................................................................................... 41 3.2.2 Limestone Extraction.................................................................................................... 45 3.2.3. Karstic Limestone Preservation................................................................................... 48 3.2.4 Summary of Modification of Karstic Limestone.......................................................... 49 Exhibit 16
x 3.3 Aquifer Drawdown.............................................................................................................. 49 3.3.1. Direct Mortality from Groundwater Pumping............................................................. 53 3.3.2 Climate Change and Aquifer Drawdown..................................................................... 54 3.3.3 Water Regulations........................................................................................................ 55 3.3.4. Summary of Aquifer Drawdown................................................................................. 55 3.4 Groundwater Contamination by Anthropogenic Sources................................................... 56 3.4.1 Contaminant Effects on Miami Cave Crayfish............................................................. 58 3.4.2 Predicted Exposure of Miami Cave Crayfish to Contaminants.................................... 59 3.4.3 Special Case: Radiation................................................................................................ 61 3.4.4 Groundwater Protection Regulations............................................................................ 64 3.4.5 Summary of Groundwater Contamination by Anthropogenic Sources........................ 65 3.5 Saltwater Intrusion.............................................................................................................. 66 3.5.1 Impact on Miami Cave Crayfish.................................................................................. 69 3.5.2 Mitigating Factors......................................................................................................... 69 3.5.3 Summary of Saltwater Intrusion................................................................................... 74 3.6 Other Possible Influences.................................................................................................... 74 3.6.1 Competition and Predation........................................................................................... 75 3.6.2 Disease.......................................................................................................................... 75 3.6.3 Overutilization.............................................................................................................. 76 3.6.4 Summary of Other Possible Influences........................................................................ 77 3.7 Summary of Influences on Viability................................................................................... 77 CHAPTER 4 - ANALYSIS OF CURRENT CONDITION......................................................... 78 4.1 Current Species Resiliency.................................................................................................. 79 4.1.1 Habitat Quantity - Quantity of Karstic Limestone Aquifer Habitat............................ 79 4.1.2 Habitat Quality - Quality of Surface Cover................................................................. 81 4.1.3 Habitat Quality - Freshwater Quality........................................................................... 85 4.1.4 Habitat Quality - Freshwater Availability.................................................................... 88 4.1.5 Habitat Availability - Combining Habitat Quantity and Quality Measures................ 89 4.2 Current Species Redundancy.............................................................................................. 91 4.3 Current Species Representation.......................................................................................... 92 4.4 Summary of Current Condition........................................................................................... 93 CHAPTER 5 - FUTURE CONDITIONS.................................................................................... 93 Exhibit 16
xi 5.1 Future Scenarios.................................................................................................................. 94 5.1.1 Scenario 1: Continuation of Current Trends................................................................. 97 5.1.2 Scenario 2: Continuation of Current Trends with Moderate Increases in Aquifer Drawdown and Contamination.............................................................................................. 98 5.1.3 Scenario 3: Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion.................................................................... 98 5.1.4 Scenario 4: Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise............................................................................................................ 99 5.2 Future Conditions.............................................................................................................. 100 5.2.1 Scenario 1: Continuation of Current Trends............................................................... 100 5.2.2 Scenario 2: Continuation of Current Trends with Moderate Increases in Aquifer Drawdown and Contamination............................................................................................ 102 5.2.3 Scenario 3: Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion.................................................................. 104 5.2.4 Scenario 4: Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise.......................................................................................................... 106 5.3 Summary of Future Conditions......................................................................................... 107 5.4 Summary of Species Viability........................................................................................... 108 5.4.1 Resiliency................................................................................................................... 109 5.4.2 Redundancy................................................................................................................ 109 5.4.3 Representation............................................................................................................ 110 LITERATURE CITED............................................................................................................... 111 APPENDIX A: PRESUMED INFLUENCE DIAGRAM FOR MIAMI CAVE CRAYFISH... 127 APPENDIX B: AGRICULTURAL LAND USE IN ENDEMIC RANGE OF MIAMI CAVE CRAYFISH................................................................................................................................. 129 APPENDIX C: PRECIPITATION CHANGE PROJECTIONS................................................ 132 APPENDIX D: PROTECTED LAND IN ENDEMIC RANGE OF MIAMI CAVE CRAYFISH
..................................................................................................................................................... 134 APPENDIX E - CURRENT CONDITION METHODOLOGY............................................... 136 Exhibit 16
1 CHAPTER 1 - INTRODUCTION The Miami cave crayfish (Procambarus milleri) is a subterranean, freshwater crustacean found in the Biscayne Aquifer on the Atlantic Coastal Ridge of southern and central Miami-Dade County, Florida. The species was petitioned for federal listing under the Endangered Species Act of 1973, as amended (Act), as a part of the 2010 Petition to List 404 Aquatic, Riparian and Wetland Species from the Southeastern United States by the Center for Biological Diversity (CBD 2010, pp. 936-938). The Species Status Assessment (SSA) framework (USFWS 2016, entire) is intended to be an in-depth review of the species biology and threats, an evaluation of its biological status, and an assessment of the resources and conditions needed to maintain long-term viability. The intent is for the SSA to be easily updated as new information becomes available and to support all functions of the Endangered Species Program from Candidate Assessment to Listing to Consultations to Recovery. As such, the SSA will be a living document that may be used to inform Endangered Species Act decision making, such as listing, recovery, Section 7, Section 10, and reclassification decisions (the former four decision types are only relevant should the species warrant listing under the Act).
This SSA for the Miami cave crayfish is intended to provide the biological support for the decision on whether to propose to list the species as threatened or endangered and, if so, to determine whether it is prudent to designate critical habitat in certain areas. Importantly, the SSA is not a decisional document by the U.S. Fish and Wildlife Service, rather it provides a review of available information strictly related to the biological status of the Miami cave crayfish. The listing decision will be made by the Service after reviewing this document and all relevant laws, regulations, and policies, and the results of a proposed decision will be announced in the Federal Register, with appropriate opportunities for public input.
For the purpose of this assessment, we define viability as the ability of the species to sustain resilient populations in natural aquifer ecosystems for at least 50 years. We chose 50 years because it is within the range of the available land use change (Carr and Zwick 2016, entire) and regional sea level change projections (Sweet et al. 2017, entire; Sweet et al. 2018, entire), and is expected to encompass at least three generations of Miami cave crayfish. Using the SSA framework (Figure 1.1), we consider what the species needs to maintain viability by characterizing the status of the species in terms of its redundancy, representation, and resiliency (Shaffer and Stein 2000, pp. 308-311; USFWS 2016, entire; Wolf et al. 2015, entire).
Resiliency is assessed at the level of populations and reflects a species ability to withstand environmental stochasticity (normal, year-to-year variations in environmental conditions),
periodic disturbances within the normal range of variation, and demographic stochasticity (normal variation in demographic rates, such as mortality and fecundity) (Redford et al. 2011, p.
40). Resiliency can be evaluated by measuring population level metrics such as demography, genetic health, connectivity, and/or habitat quantity, quality, configuration, and heterogeneity.
Redundancy is measured on the species level and reflects the ability of a species to withstand catastrophic events. Catastrophes are stochastic events that are expected to lead to population Exhibit 16
2 collapse regardless of population health and for which adaptation is unlikely (Mangal and Tier 1993, p. 1083). Redundancy can best be assessed by analyzing the number and distribution of populations relative to the scale of anticipated species-relevant catastrophic events.
Representation is also evaluated at the species level and is the ability of a species to adapt to both near-term and long-term changes in its physical and biological environments. This adaptive capacity (i.e., ability to adapt to new environments) is essential for viability as species need to adapt to their continuously changing environments (Nicotra et al. 2015, p. 1269). A species adaptive potential can be assessed by evaluating intraspecific genetic, ecological, morphological, and/or behavioral variability.
Figure 1.1. Framework of the Species Status Assessment.
To evaluate the current and future viability of Miami cave crayfish, we evaluated a range of conditions to characterize the species redundancy, representation, and resiliency (together, the 3Rs). This SSA provides a thorough account of biology and natural history and assesses key influences affecting the current and future viability of the species.
This SSA includes: 1. a review of the taxonomy, morphology, life history, habitat use, and other pertinent biological traits of Miami cave crayfish (Chapter 2); 2. a characterization of the Exhibit 16
3 historical and current distribution of the species (Chapter 2); 3. a description of Miami cave crayfish resource needs at the individual, population, and species levels (Chapter 2); 4. a review of the factors that influence the current and future status of the species (Chapter 3); 5. an analysis of the current condition of the species with respect to the 3Rs (Chapter 4), and 6. a synopsis of the factors characterized in earlier chapters as a means of examining the future viability of the species (Chapter 5). This document is a compilation of the best available scientific information (and associated uncertainties regarding that information) used to assess the viability of Miami cave crayfish.
CHAPTER 2 - SPECIES BIOLOGY, LIFE HISTORY, AND NEEDS In this chapter, we provide basic biological information about the Miami cave crayfish, including its taxonomic history and relationships, morphological description, relevant life history traits, natural habitat, and historical and current distribution. We use this biological information as the basis for outlining the resource needs of Miami cave crayfish at the individual, population, and species levels.
2.1 Taxonomy and Evolutionary History Encompassing 178 described species worldwide and nearly half of all American crayfish taxa, the genus Procambarus is the largest genus of freshwater crayfish. Although the monophyly of this New World genus has been called into question by recent molecular analyses, the taxon has historically been subdivided into 15-17 distinct subgenera, which include Acucauda, Austrocambarus, Capillicambarus, Distocambarus, Girardiella, Hagenides, Leconticambarus, Lonnbergius, Mexicambarus, Ortmannicus, Remoticambarus, Paracambarus, Pennides, Procambarus, Scapulicambarus, Tenuicambarus, and Villalobosus (Hobbs 1984, entire; Owen et al. 2015, pp. 4-5; Longshaw and Stebbing 2016, p. 206). The distinguishing feature of the genus Procambarus is the presence of four terminal elements of the male gonopod. Although the majority of the diversity in this genus is within the southeastern United States, representatives extend throughout much of the eastern portion of North America, along the eastern seaboard and the coastal regions of the Gulf of Mexico, up the Mississippi River drainage as far as Wisconsin, and south through Texas into Mexico. Several species of Procambarus extend through Central America to Honduras, while three are endemic to Cuba (Hobbs 1984, entire; Longshaw and Stebbing 2016, p. 206).
The Miami cave crayfish (Procambarus milleri; assigned to the subgenus Leconticambarus) was first described from specimens collected from a 22 foot (ft) (6.7 meter (m)) deep well drilled into the Biscayne Aquifer in Miami-Dade County, Florida (Hobbs 1971, entire). The species has recently adapted to the subterranean environment as is indicated by the presence of both pigment and eye facets in individuals (Hobbs 1971, pp. 121-122; Caine 1974, pp. 490-491; Loftus and Exhibit 16
4 Trexler 2004, p. 50; Loftus and Bruno 2006, p. 135). The Miami cave crayfish is considered a valid taxon and meets the ESA definition of a species.
The currently accepted classification is (Integrated Taxonomic Information System 2021):
Phylum:
Arthropoda Class:
Malacostraca Order:
Decapoda Family:
Cambaridae Genus:
Procambarus Species:
Procambarus milleri 2.2 Morphological Description The Miami cave crayfish was first described by Hobbs (1971, entire) based on six form I (reproductive adult stage) males, eight form II (nonreproductive adult stage) males, three juvenile males, and a single juvenile female. Physical description of the species has been augmented by further study of additional specimens of wild-collected juveniles and adults of both sexes and of a captive population of Miami cave crayfish founded in 1992 (Radice and Loftus 1995, entire; Loftus and Trexler 2004, pp. 36-50; Loftus and Bruno 2006, entire). A detailed description of form I males is provided by Hobbs (1971, entire) (Figures 2.2.1).
Exhibit 16
5 Figure 2.2.1. Anatomy of form I male of Miami cave crayfish. Hobbs (1971, p. 117): 1 and 2, Mesial views of first pleopods; 3, Dorsal view of carapace; 4 and 5, Lateral views of first pleopods; 6, Epistome; 7, Antennal scale; 8, Basal podomeres of third and fourth pereiopods; 9, Caudal view of first pleopods; 10, Lateral view of carapace; 11, Dorsal view of distal podomeres of right cheliped.
In contrast to the sexual dimorphism exhibited by many crayfish species, females and males of the Miami cave crayfish do not demonstrate any significant size differences and adults of both sexes bear relatively large claws (Loftus and Trexler 2004, p. 47; Loftus and Bruno 2006, p. 135; Radice and Loftus 1995, pp. 113-114). The carapace lengths reported in wild adults range from Exhibit 16
6 0.3 inch (8 millimeters (mm)) up to 1.1 inches (27.4 mm) (Hobbs 1971, p. 121; Loftus and Trexler 2004, p. 45; Loftus and Bruno 2006, p. 135; Cook et al. 2018, suppl.). Captive-bred adults are larger than are those sampled from wild populations, most likely due to the increased food availability and reduced predatory and competitive pressures in captive settings. The average carapace length of captive adult Miami cave crayfish is 0.05 inch (1.25 mm) longer than that of wild adults (Loftus and Trexler 2004, pp. 46-47; Loftus and Bruno 2006, p. 135).
Although first described as unpigmented by Hobbs (1971, p. 115), adult Miami cave crayfish have black eye spots and are most commonly dark orange in color with a distinctive reddish stripe extending medially on the dorsal surface from the first abdominal segment to the sixth (Loftus and Trexler 2004, pp. 45-47; Loftus and Bruno 2006, p. 135; Radice and Loftus 1995, pp. 114, 116) (Figure 2.2.2). Approximately 83 percent of 2,451 adult, captive-reared Miami crayfish exhibited this color pattern, while 8.8 percent displayed a more muted orange coloration
((Loftus and Trexler 2004, pp. 45-47; Loftus and Bruno 2006, p. 135). Less common color variations demonstrated by captive-born individuals included hues of pink, blue, red, green, beige, and brown, accounting for a combined total of 8.5 percent of the adults inspected (Loftus and Trexler 2004, pp. 45-47; Loftus and Bruno 2006, p. 135; Radice and Loftus 1995, pp. 114, 116). Egg masses are pigmented, and the majority of captive-bred juveniles bear red pigmentation upon hatching (Loftus and Trexler 2004, pp. 46-47) (Figure 2.2.2). However, 10 percent of the captive juveniles examined in 1994 were albino, a trait lost in the captive population following this generation as a result of disease-related die-off (Loftus and Trexler 2004, pp. 46-47). The presence of pigmentation in the majority of wild and captive Miami cave crayfish suggests that the species is still in the process of adapting to its subterranean environment (i.e., stygophilic (adapted to living in both surface and subterranean habitats) versus stygobitic (strictly subterranean)) (Hobbs 1971, pp. 121-122; Caine 1974, pp. 490-491; Loftus and Trexler 2004, p. 50; Loftus and Bruno 2006, p. 135).
Exhibit 16
7 Figure 2.2.2. Typical coloration of Miami cave crayfish. Loftus and Trexler (2004, p. 145): a, Dorsal view of form I male with dark orange color variation; b, Dorsal view of juvenile with highly-pigmented cephalosome.
2.3 Life History Most of our knowledge regarding the life history of Miami cave crayfish comes from a study of a captive colony of the species, which was described by Radice and Loftus (1995) and Loftus and Trexler (2004). This colony was started in 1992 with seven wild-caught adults, which were bred for the pet trade in an aquaculture facility south of Miami, Florida (Radice and Loftus 1995, pp.
112, 114). Although the colony no longer exists, individuals from the original Florida stock served as founders for the captive-bred individuals that currently exist in the European and Russian aquarium trade (Faulkes et al. 2015, p. 77; Loftus, pers. comm. 2021). In addition to housing study animals in unnatural densities, captive care typically provides conditions that Exhibit 16
8 maximize fecundity and growth in crayfish. Consequently, the reproductive ecology detailed in this section may not accurately represent that of wild populations of Miami cave crayfish.
However, analyses of captive individuals can be helpful for estimating general parameters of reproductive size, fecundity, and seasonality and duration of breeding for wild populations of the species.
Miami cave crayfish begin life as fertilized black eggs (~0.08 inch (~2 mm) in diameter) adhering to the pleopods underneath a females abdomen (Figure 2.3.1). Mature females produced up to 100 eggs in captivity, averaging 50 eggs across the 37 females measured (Radice and Loftus 1995, p. 114; Loftus and Trexler 2004, pp. 47-48; Loftus and Bruno 2006, p. 135).
Gravid females are larger than non-gravid females, and larger Miami cave crayfish produce more eggs per clutch (Loftus and Trexler 2004, pp. 47-48). Miami cave crayfish lay fewer and larger eggs in comparison to the closely-related, surface-dwelling Everglades crayfish (Procambarus alleni), a general reproductive pattern predicted by life-history theory. In order to optimize reproductive success over a lifetime, the food-resource-limited subterranean crayfish species benefits from investing in less, but larger offspring in a clutch, while the surface crayfish with more extensive food resources maximizes its success with more eggs of smaller size per clutch (Loftus and Trexler 2004, p. 48; Loftus and Bruno 2006, p. 135).
Figure 2.3.1. Radice and Loftus (1995, p. 112): Ventral view of gravid female Miami cave crayfish. Note the black, fertilized eggs and several non-black eggs mixed in with the black eggs that represent infertile or unfertilized eggs.
Exhibit 16
9 After hatching, the young of crayfish species attach to the female by a telson thread, a ropelike structure binding the eggshell attached to the last segment of the abdomen of the female to the abdomen of the hatchling (Vogt and Tolley 2004, pp. 569-571). Young crayfish undergo a series of molts (a process of shedding, or molting, their old exoskeleton, and growing and hardening the new exoskeleton) while still attached to the female (Jezerinac et al. 1995, p. 17; Taylor et al.
1996, pp. 26-27). During this time, females will care for and protect their young (Vogt and Tolley 2004, p. 573). Juveniles then leave the female to begin life as free-living individuals. At water temperatures of 75.2 degrees Fahrenheit (F) (24Celsius (C)) in captivity, Miami cave crayfish juveniles are released by the female in approximately three to four weeks (Loftus and Trexler 2004, p. 48).
In captivity, Miami cave crayfish exhibit continuous reproduction throughout the year, peaking in the late summer through early winter. In captive conditions, gravid females were present in every month with the highest annual abundance recorded in January through March (Loftus and Trexler 2004, pp. 47-48; Loftus and Bruno 2006, p. 135). Similarly, captive free-living juveniles were sampled in every month, becoming most numerous in summer through winter counts (Loftus and Trexler 2004, p. 47). Females of this species have the capacity to breed more than once a year as demonstrated by a captive female who produced two successful summer broods in just 3 1/2 months. On average, throughout the year, 91 percent of gravid females in a captive population of Miami cave crayfish had fertile eggs, while the remaining 9 percent had attached juveniles (Loftus and Trexler 2004, pp. 47-48).
Molting is one of the critical life history stages of crayfish. Starting from the time of hatching and continuing until death, crayfish go through a continuous series of molts (Taylor et al. 1996, pp. 26-27; Jones and Eversole 2011, p. 648; Jones 2012, p. 99). This enables crayfish to increase in size throughout life. For instance, a wild-caught Miami cave crayfish kept in captivity molted twice within a month, increasing its carapace length by 0.06 inch (1.6 mm) in the process (Hobbs 1971, p. 122).
In addition to increasing in size, when male crayfish molt, they may alternate between reproductively active form I and nonreproductive form II states, a pattern observed in wild Miami cave crayfish (Hobbs 1971, p. 122; Jezerinac et al. 1995, pp. 17; Taylor et al. 1996, pp.
26-27). Molting is a vulnerable life stage for crayfish because they are soft and have difficulty moving, exposing them to increased risk of predation or injury. During this time, crayfish are also more sensitive to contaminants and water quality degradation due to a variety of interrelated physiological factors (Taylor et al. 2007, p. 374; Wigginton and Birge 2007, p. 548; Loughman and Welsh 2010, p. 74).
Molting appears to occur year-round for both sexes and all life stages of Miami cave crayfish as confirmed by both wild collections of adult males and studies of the captive population over three years (Hobbs 1971, p. 122; Loftus and Trexler 2004, p. 47). Captive-reared females molt within two to three weeks of releasing their young, typically mating shortly after completing this molt (Loftus and Trexler 2004, p. 48).
Exhibit 16
10 The age of reproductive maturity and longevity of Miami cave crayfish is unknown. However, in concurrence with life history theory, subterranean species of crayfish generally live longer than their surface counterparts, up to several decades in some cases (Taylor et al. 1996, p. 27). Based on a five-year mark-recapture study of 3,800 crayfish of different species inhabiting 3 cave systems, the average life span for cave crayfish was estimated to be approximately 20 years (Longshaw and Stebbing 2016, p. 68). Although an initial study that focused specifically on the Southern cave crayfish (Orconectes australis) estimated the species longevity to be approximately 176 years, more probable predictions range from 22 years to upwards of 50 years (Huryn et al. 2008, pp. 1, 12-15; Vernarsky et al. 2012, entire). Despite our knowledge gaps in the life history traits of the species, we were able to generate a conceptual diagram of the major life stages of the Miami cave crayfish based on all available data (Figure 2.3.2).
Figure 2.3.2. Conceptual model of the life history of Miami cave crayfish. See text for detailed explanation.
2.4 Other Pertinent Behaviors Miami cave crayfish are opportunistic omnivores, primarily consuming surficial detritus that filters down through the porous limestone bedding in which their aquifer habitat is bound Exhibit 16
11 (Radice and Loftus 1995, p. 114). Wild individuals may also consume smaller, sympatric crustaceans. Amphipods and isopods were found in the same trap in which the first described specimens of Miami cave crayfish were recovered (Hobbs 1971, p. 114). Potential microcrustacean prey recovered from wells along the coastal ridge in the Homestead area include low densities of Caecidotea isopods, Hyalella amphipods, and an undescribed Crangonyx amphipod (Loftus and Trexler 2004, pp. 43-44). In captivity, juveniles and adults of Miami cave crayfish were successfully sustained on commercial algal-based trout food chow and Spirulina tropical-fish flake food supplemented by Hyalella spp. (Radice and Loftus 1995, pp. 114, 116; Loftus and Trexler 2004, p. 39).
Franz and Lee (1982, pp. 74-75) postulate that cave crayfish developed more efficient metabolisms relative to surface-dwelling crayfish species to adapt to life in subterranean aquatic habitats where detritus inputs are low. Since subterranean crayfish can more efficiently process the available food, the crayfish experience lower intraspecific competitive pressure and exhibit significantly less aggressive behavior than similar species found in higher energy systems (Hobbs and Means 1972, p. 401; Caine 1978, pp. 323, 325). The social behavior of captive Miami cave crayfish adheres to this model. Even when kept in unnaturally high densities, captive individuals exhibit a relatively tolerant nature towards tankmates (Radice and Loftus1995, p. 116). No incidents of territoriality, cannibalism, or other forms of aggression have been described for captive populations of Miami cave crayfish, in stark contrast to the closely-related, surface-dwelling Everglades crayfish, which regularly exhibits these aggressive behaviors in captivity (Radice and Loftus 1995, p. 116).
Despite the absence of overt intraspecific aggression and any reported predation of the species within their natural habitats, captive Miami cave crayfish display sheltering behaviors in response to threatening interactions (e.g., video footage available at https://youtube.com/watch?v=Z1e-Cs-m1ks). In their natural habitat, the hiding behavior of free-living juveniles and adults is facilitated by ample access to cover in the form of the structurally-complex, macroporous limestone of their aquifer environment (Wacker et al. 2015, pp. 16-25).
2.5 Habitat Miami cave crayfish have been collected from wells and excavations 7.9-36 ft (2.41-11 m) deep (the majority between ~ 22.9-36 ft (~7 and 11 m) deep) in the Miami Limestone and Fort Thompson limestone formation within the Biscayne Aquifer along the Atlantic Coastal Ridge in southern and central Miami-Dade County, Florida (Hobbs 1971, pp. 114, 121; Radice and Loftus 1995, pp. 112, 114; Loftus and Trexler 2004, p. 45; Loftus and Bruno 2006, p. 135; P. Moler pers. comm. 2021). Despite significant sampling effort, no specimens have been recovered from groundwater wells of similar depths within Everglades National Park, even those sampled along the western-most, isolated segment of the Atlantic Coastal Ridge at Long Pine Key (Loftus and Trexler 2004, pp. 37-38, 43, 45; Loftus and Bruno 2006, p. 135).
Exhibit 16
12 2.5.1 Biscayne Aquifer The Biscayne Aquifer is one of four principal aquifer systems in Florida that are exposed at or near the land surface and are recharged primarily by precipitation (Walsh 2001, p. 78) (Figures 2.5.1 and 2.5.2). Predominantly composed of Pleistocene karstic limestone, the Biscayne Aquifer is the primary source of drinking water for over 3 million residents in Broward, Miami-Dade, and Palm Beach counties and provides water for recreational, commercial, and agricultural uses throughout the region (Wacker et al. 2014, p. 1; Whitman and Yeboah-Forson 2015, p.
781). The thickness of the Biscayne Aquifer in Miami-Dade County ranges approximately from 65.6 ft (20 m) in the west to 131.2 ft (40 m) in the east along the Biscayne Bay (Fish and Stewart 1991, p.12).
Figure 2.5.1. The four major aquifer systems of Florida: undefined surficial aquifers, Sand and gravel aquifer, Biscayne Aquifer, and the Floridan aquifer system with its intermediate confining units (https://fldep.dep.state.fl.us/swapp/Aquifer.asp; Accessed May 24, 2021.).
Within the current and historical collection locations of the Miami cave crayfish, the aquifer system is primarily composed of the Miami Limestone underlain by the Fort Thompson Exhibit 16
13 Formation (Figure 2.5.2). In eastern Miami-Dade County, the Miami Limestone crops out at the surface and varies in thickness from 3 m in the west to 11 m on the Atlantic Coastal Ridge in the east (Fish and Stewart 1991, pp. 13, 32, 47; Whitman and Yeboah-Forson 2015, p.782). The Fort Thompson Formation lies below the Miami Limestone and was deposited as very porous marine, brackish, and freshwater limestones (Fish and Stewart 1991, p. 33). Interfingering with the Anastasia Formation in some coastal areas, the Fort Thompson Formation shares the eastward thickening trend exhibited by the Miami Limestone and can reach depths exceeding 78.7 ft (24 m) below the surface (Fish and Stewart 1991, pp. 33, 47). Miami cave crayfish have been collected from both the Miami Limestone and Fort Thompson Formation (Table 2.5.1). Although individuals have not been collected below 36 ft (11 m), we predict that the increased thickness of both these limestone units as well as the depth of the Biscayne Aquifer in the eastern portion of the Atlantic Coastal Ridge equates with greater habitat availability for the species in this region (Figure 2.5.3).
Figure 2.5.2. Geologic and hydrogeologic units of the Biscayne Aquifer system in Miami-Dade County, Florida from Wacker et al. (2014, p.4). Miami cave crayfish inhabit the Biscayne Aquifer, which encompasses both the Miami Limestone and Fort Thompson Formation.
Exhibit 16
14 Figure 2.5.3. Thickness of the Biscayne Aquifer in the region of the Atlantic Coastal Ridge in central and southeastern Miami-Dade County, Florida from Hughes and White (2016, p. 26).
2.5.2 Atlantic Coastal Ridge Exhibit 16
15 Each historical and current location of Miami cave crayfish coincides with the Atlantic Coastal Ridge east of the Everglades wetland ecosystem (Hobbs 1971, pp. 114, 121; Loftus and Trexler 2004, p. 45; Loftus and Bruno 2006, p. 135; Radice and Loftus 1995, pp. 112, 114; Cook et al.
2018, suppl.; P. Moler pers. comm. 2021). The Atlantic Coastal Ridge is a northeast to southwest trending elevated feature, varying between 1.8-10 miles (mi) (3-16 kilometers (km)) in width and rising 3.2-28.2 ft (1-8.6 m) above sea level between Everglades National Park, Homestead, and north Miami in Miami-Dade County (Figure 2.5.4) (Fish and Stewart 1991, p. 4, Wacker et al. 2014, p. 26; Whitman and Yeboah-Forson 2015, pp. 782, 790; Meeder and Harlem 2019, pp. 560-561).
On the surface, the Atlantic Coastal Ridge is covered by a layer of sand, so thin in some regions that infiltration into the bedrock is heightened. The best drainage in Miami-Dade County occurs on the Atlantic Coastal Ridge, in stark contrast to the poor drainage of the surrounding areas marl or peat and muck cover, which can be several thick feet in north-western and north-central Miami-Dade County (Fish and Stewart 1991, p. 8). For this reason, the Atlantic Coastal Ridge serves as a key recharge area for the Biscayne Aquifer system (Fish and Stewart 1991, p. 47).
Influx of organic carbon (in the form of both dissolved organic matter and coarse particulate organic matter) into groundwater ecosystems declines with depth and distance from the recharge area of aquifers (Hancock et al. 2005, p. 104). Since Miami cave crayfish depend primarily on detritus that filters into their subterranean habitats from the surface (Section 2.4), the enhanced filtration facilitated by the Atlantic Coastal Ridges sandy substrate provides more nutrient flow into the environment and, thus, greater food availability for the species than does the mucky substrate of the Everglades wetland ecosystem.
Exhibit 16
16 Figure 2.5.4. Physiographic features of Miami-Dade County from Lietz (1999, p. 8) with approximate locations from which Miami cave crayfish have been collected (refer to Figure 3.1.1 for more detailed location information). Note the extension of the Atlantic Coastal Ridge (charcoal grey) along the eastern coast of Miami-Dade County, Florida. The western-most section of the Atlantic Coastal Ridge includes Long Pine Key within Everglades National Park.
Exhibit 16
17 When reported, the depths from which Miami cave crayfish have been sampled place them within the Miami Limestone or Fort Thompson Formation (Table 2.5.1). As elsewhere in Miami-Dade County, the Fort Thompson Formation of the Atlantic Coastal Ridge is marked by interconnected networks of well-developed open cavities in the rock, which are so numerous and large (up to 9.4 inches (5 centimeters (cm)) in diameter) that the formation resembles a sponge (Fish and Stewart 1991, pp. 30, 33).
The absence of Miami cave crayfish from the Miami Limestone beneath the Everglades wetland ecosystem is likely related to the limestone units reduced porosity in comparison to that underlaying the Atlantic Coastal Ridge. The Miami Limestone of the Atlantic Coastal Ridge is heavily-bioturbated, containing many burrows, borings, and root traces that create cavities within the limestone. In addition, the limestone underneath the Atlantic Coastal Ridge is rich in aragonite, a soluble form of carbonate. The increased elevation of the Miami Limestone on the Atlantic Coastal Ridge provides a greater opportunity for the aragonite to weather and dissolve, creating abundant vertical and horizontal openings within the limestone (Wacker et al. 2014, pp.
15, 18-23, 24-27, 35, 38; Whitman and Yeboah-Forson 2015, pp. 782, 790). Evidence of the higher porosity of this unit of Miami Limestone is evident in the abundance of larger dissolution features (e.g., sinkholes and subterranean caverns) on the Atlantic Coastal Ridge when compared to the adjacent Everglades wetland ecosystem (Cressler 1993, entire; Florea and Yuellig 2007, pp. 3-4; Meeder and Harlem 2019, p. 559, 561, 574). Depending on the size and connectivity of these cavities, juvenile and adult Miami cave crayfish may use them when traveling within the aquifer system (Loftus and Trexler 2004, p. 49). The openings also provide potential hiding spots for avoiding intra-and/or interspecific aggression or predation, however rare those events may be (Section 2.4).
In contrast, the Miami Limestone underlying the Everglades wetland ecosystem consists of calcite-rich sandy carbonates in which any cavities present are partly to completely cemented with lime mud and sand. The lower elevation of the Everglades wetland ecosystem and the less soluble nature of calcite slows the weathering of this limestone, greatly reducing the number and connectivity of megaporosities that could potentially be used as Miami cave crayfish habitat.
(Fish and Stewart 1991, pp. 27, 30; Whitman and Yeboah-Forson 2015, pp. 782, 790). This difference in the number and connectivity of megaporosities likely explains why Miami cave crayfish are only found on the Atlantic Coastal Ridge.
Table 2.5.1. Depths below surface and geologic formation from which Miami cave crayfish were collected as reported for historical and current records. Formations were assigned on the basis of formation depths recorded by Fish and Stewart (1991, p. 6, plates 3 and 4). ML=Miami Limestone. FT=Fort Thompson Formation. Wells G-3312 and G-3311 were used to determine the range of depths below surface for ML (Surface to 5-6 m) and FT (Top 5-6 m, Bottom 15-24 m) for sites north of SW 152nd St., Florida 992, Miami-Dade County, Florida. Wells G-3314 and G-3315 were used to determine the range of depths below surface for ML (Surface to 5-11 m) and FT (Top 5-11 m, Bottom 18-23 m) for sites south of SW 152nd St., Florida 992, Miami-Dade County, Florida.
Exhibit 16
18 Collection Date Depth of Collection:
ft (m)
Formation Citation 1968 18-22 (5.5-6.7)
ML Hobbs 1971, p. 121 1992 25-30 (7.6-9.1)
ML and/or FT Radice and Loftus 1995, p. 114 2000-2004 23-36 (7-11)
Northern cluster: FT Southern cluster: ML and/or FT Loftus and Trexler 2004, p. 45; Loftus and Bruno 2006, p.
135 2001 7.9 (2.41)
ML Loftus and Trexler 2004, p. 45 2018 12.1 (3.7)
ML Cook et al. 2018, suppl.
2.5.3 Hydrological Factors Highly connected areas of megaporosity within the Miami Limestone and Fort Thompson Formation on the Atlantic Coastal Ridge also support groundwater movement through Miami cave crayfish habitat. Groundwater moves through the Biscayne Aquifer in two major flow units, which are both dependent on networks of open cavities for flow through the limestone formations (Wacker et al. 2014, pp. 4, 27-40). This connectivity is reflected in the regional variation of porosity across aquifer depth: the highest porosity within the Biscayne Aquifer in Miami-Dade County is on the Atlantic Coastal Ridge, where the greatest porosities are along the center of the ridge and below 16.4 ft (5 m) in depth (Whitman and Yeboah-Forson 2015, pp.
784-790).
Notably, the majority of historical collection sites for Miami cave crayfish record specimens from depths below 16.4 ft (5 m) in the area of maximum porosity on the Atlantic Coastal Ridge (Table 2.5.1). The increased connectivity of cavities within the Atlantic Coastal Ridges underlying limestone leads to elevated groundwater flow and exchange, which results in higher overall water quality (e.g., elevated dissolved oxygen levels) within the aquifer habitats of the Miami cave crayfish (Fish and Stewart 1991, p. 47; Wacker et al. 2014, pp. 27-40). Increased groundwater flow may also assist in more evenly dispersing detritus filtering down from the surface throughout the aquifer system, providing more feeding opportunities for the species throughout the Atlantic Coastal Ridge (Hancock et al. 2005, pp. 104-105).
Although water quality requirements for the species are currently unknown, between 2000 and 2004, Loftus and Trexler (2004) conducted year-round physicochemical water monitoring of groundwater in wells within the Biscayne Aquifer within the same area and at comparable depths to wells from which Miami cave crayfish were collected (several of these wells provided samples of the species during this time period). These values provide our best estimates for the water conditions in which Miami cave crayfish may live in the wild. The researchers reported relatively low dissolved oxygen levels in the groundwater monitored. Values generally ranged from 2-7 percent saturation, rarely exceeding 10 percent saturation. However, higher oxygen Exhibit 16
19 levels were exploited by Miami cave crayfish inhabiting freshly-exposed groundwater: ranging from approximately 36.5 percent - 49 percent saturation over one week in October of 2004 (Loftus and Trexler 2004, pp. 45, 144; Loftus 2021, pers. comm.).
In the same study, groundwater temperatures demonstrated little seasonal change. Temperatures averaged around 73F (23C) in the spring and approximately 77F (25C) in the fall and winter (Loftus and Trexler 2004, p. 40). In captivity, successfully-reproducing Miami cave crayfish were maintained at water temperatures within the range of groundwater temperature (between 67.5 and 79F (19.72 and 26.12°C)) (Loftus and Trexler 2004, pp. 39-40, 46). Similarly, the pH of groundwater in the aquifer fluctuated minimally across seasons, averaging approximately 7.3, slightly above neutral (Loftus and Trexler 2004, p. 40). Miami cave crayfish does best in slightly alkaline water in captivity (Radice and Loftus 1995, p. 116). When there was a loss of water quality (i.e., a drop in dissolved oxygen levels, elevated water temperature, and probable excess of nitrogen levels) for over a week from an electrical failure at the facility maintaining the captive population, all Miami cave crayfish died (Loftus 2021, pers. comm.).
2.5.4 Habitat Overview In summary, the unique hydrology and geology of southern Florida account for the highly-endemic range of the Miami cave crayfish within the Biscayne Aquifer along the Atlantic Coastal Ridge of Miami-Dade County. The aquifer system supplies year-round and abundant subterranean freshwater reserves, while the numerous interconnected networks of cavities within the Atlantic Coastal Ridges Miami Limestone and Fort Thompson Formation provide: 1.
structures through which juvenile and adult Miami cave crayfish can travel between areas within the aquifer system, facilitating connectivity, 2. microhabitats in which individuals can shelter or hide from intra-and interspecific threats, and 3. enhanced groundwater flow for improved water quality and food availability. The Atlantic Coastal Ridges sandy surficial substrate enhances filtration to the underlying Miami Limestone, which increases the flow of detritus into the subterranean habitats of Miami cave crayfish. The absence of the species from the adjacent Everglades parallels the absence of extensive porosity in the Miami Limestone west of the Atlantic Coastal Ridge and of significant surficial flow into the aquifer, which is hampered in the Everglades wetland ecosystem by marl or peat and muck cover.
2.6 Historical and Current Range and Distribution The historical and current range of the Miami cave crayfish is restricted to areas of the Biscayne Aquifer along the Atlantic Coastal Ridge in southern and central Miami-Dade County, Florida east of the Everglades wetland ecosystem (Figure 2.6.1) (Hobbs 1971, pp. 114, 121; Loftus and Trexler 2004, p. 45; Loftus and Bruno 2006, p. 135; Radice and Loftus 1995, pp. 112, 114; Cook et al. 2018, suppl.; P. Moler pers. comm. 2021). Hobbs (1971, entire) first described the species Exhibit 16
20 based on specimens recovered from a well trap on the grounds of a nursery south of Miami in 1968. The next confirmed report of the species was from a fish farm in Homestead in 1992.
Two individuals were initially discovered during a well blowout, followed by seven additional specimens captured over two months in a baited trap placed 24.9 ft (7.6 m) down the well hole (Radice and Loftus 1995, pp. 112, 114).
A comprehensive effort to survey for Miami cave crayfish in wells within and outside of Everglades National Park was conducted from 2000-2004 (Loftus and Trexler 2004, pp. 2, 3, 35-50). The researchers failed to recover any from 34 wells sampled within the Everglades wetland ecosystem (19 in Everglades National Park and 15 adjacent to the Parks border). Surveys included portions of the southwestern most extension of the Atlantic Coastal Ridge within Everglades National Park (Figure 2.5.4) (Loftus and Trexler 2004, pp. 37-40, 42-45).
Although areas of the Atlantic Coastal Ridge north of Miami have not been comprehensively surveyed, no public sightings of subterranean crayfish have been reported from this region historically or currently (Cook et al. 2018, entire; Loftus pers. comm. 2021). In addition, the Atlantic Coastal Ridge located north of Flagler Dr. in Miami is unlikely to sustain populations of the species since sandy substrate cements many of the cavities in the subterranean Miami Limestone north of this region (Loftus pers. comm. 2021). For these reasons, we determine that there is no evidence at this time to suggest Miami cave crayfish live in any other segments of the Atlantic Coastal Ridge than that located approximately between Miami and south of Homestead (Figures ES1 and 2.5.4).
The 2000-2004 survey effort successfully identified twelve new locations for the species on the Atlantic Coastal Ridge described above (Figure 2.6.1). Despite using a variety of sampling techniques (e.g., baited vials, pumping, bottle traps, substrate traps, and underwater video),
crayfish were difficult to capture and detection rates were very low even for wells that had previously produced crayfish specimens (Loftus and Trexler 2004, pp. 37-40, 42-45; Loftus pers.
comm. 2021). However, at one location only 2.41 m (7.9 ft) below the surface, 33 crayfish were recovered in three visits over three weeks (Loftus and Trexler 2004, p. 45).
In 2009, two crayfish were collected opportunistically following their exposure during the excavation of a small fish pool in the Pinecrest region south of Miami (P. Moler pers. comm.
2021). The most recent Miami cave crayfish survey effort has been hampered by limited access to private, county, and federal lands as well as SARS-CoV-2 restrictions. However, initial well sampling and public outreach in 2018 resulted in a total of six individuals being collected from three sites (Cook et al. 2018, entire) (Figure 2.6.1).
Exhibit 16
21 Figure 2.6.1. Current and historical locations of Miami cave crayfish. Red square = type locality (Hobbs 1971, p. 114). Blue triangle = fish farm study site with collections from 1992 and subsequent years (Radice and Loftus 1995, pp. 112, 114). Green circles = 2000-2004 collection sites (Loftus and Trexler 2004, p. 13). Purple diamond = 2009 collection site (P. Moler pers.
comm. 2021). Yellow stars = 2018 collections sites (Cook et al. 2018, suppl.).
Exhibit 16
22 Historically, all Miami cave crayfish were likely part of one metapopulation that had some degree of connectivity. There is no information available regarding the demographic, ecological, and/or genetic processes that define the spatial structure of wild Miami cave crayfish populations. However, a series of transverse glades dissect the Atlantic Coastal Ridge in a general northwest to southeast orientation and may be used to delineate distinct analysis units of the species (Figure 2.6.2).
Transverse glades are valleys that were formed by subsurface collapse of karst conduits beginning around 2000-3000 years ago. Following valley formation, layers of marl or peat were deposited and began filling the valley floor and acting as a seal to the exposed limestone (Meeder and Harlem 2019, entire). Starting in 1909, several of these karst valleys were dredged and modified to serve as canals for the drainage of the Everglades wetland ecosystem (Fish and Stewart 1991, p. 44). Although we do not know when Miami cave crayfish first entered their subterranean aquifer habitats or if they had once been widespread in the region (i.e., in the Everglades wetland ecosystem) (Hobbs 1971, pp. 121-122; Caine 1974, pp. 490-491; Loftus and Trexler 2004, p. 50; Loftus and Bruno 2006, p. 135), the species would have been isolated on the Atlantic Coastal Ridge when largescale marl and peat deposition began in the Everglades wetland ecosystem and groundwater flows became horizontal, shifting to the east and southwards from the Everglades basin (Gleason and Stone 1994, pp.166-168; Meeder and Harlem 2019, pp. 573-574). Therefore, a metapopulation of Miami cave crayfish on the Atlantic Coastal Ridge would have been separated into geographically-isolated populations either when the karst valleys first formed or, more recently, when canals were cut through these transverse glades in the 20th century.
Currently, primary canals that completely dissect the Atlantic Coastal Ridge and cut through both the Miami Limestone and the underlying Fort Thompson Formation serve to effectively isolate analysis units of Miami cave crayfish (Figure 2.6.2). Analysis units 2, 3, 4, 6, and 7 are confirmed by historical and/or current records, whereas analysis unit 1 is represented by an anecdotal report of subterranean crayfish remains recovered from a well provided by a member of the public (Hobbs 1971, pp. 114, 121; Loftus and Trexler 2004, p. 45; Loftus and Bruno 2006,
- p. 135; Radice and Loftus 1995, pp. 112, 114; Cook et al. 2018, suppl.; Loftus pers. comm.
2021). Although analysis unit 5 has not been sampled to date, we consider at least the species historical occurrence within this area is highly probable based on the presence of suitable habitat in and the existence of confirmed analysis units adjacent to this unit.
Exhibit 16
23 Figure 2.6.2. Delineation of distinct analysis units of Miami cave crayfish (indicated by bold numbers) bounded by the Atlantic Coastal Ridge and primary canals in Miami-Dade County, Florida.
2.7 Needs of the Miami Cave Crayfish As discussed in Chapter 1, for the purpose of this assessment, we define viability as the ability of the species to sustain populations in natural karstic aquifer ecosystems within a biologically meaningful timeframe (in this case, 50 years). We synthesized the biology, life history, and ecology of the species as a basis for defining the individual, population, and species needs required to sustain the viability of Miami cave crayfish.
Exhibit 16
24 2.7.1 Individual Needs The habitat elements that we identified as important to Miami cave crayfish individuals at each life stage include: 1. freshwater of sufficient water quality and quantity, 2. overlying surface cover that facilitates nutrient flow into subterranean ecosystems, and 3. karstic limestone substrate marked by a vertical and horizontal network of megaporosities. These elements allow for individuals to have sufficient food and shelter resources to grow, reach maturity, and reproduce (Table 2.7.1).
Table 2.7.1. Summary of life history and resource needs of Miami cave crayfish. CL= Carapace length, F=feeding, R=reproduction, S=shelter.
Life Stage Resources and/or circumstances needed for INDIVIDUALS to complete each life stage Resource Function (F,R,S)
Information Source Eggs/Embryos Freshwater availability (water quantity)
Sufficient water quality Gene flow among subpopulations Sexually mature females R
Radice and Loftus 1995, pp. 114, 116 Loftus and Trexler 2004, pp. 39-40, 45-48 Juveniles (pre-release from female)
Freshwater availability (water quantity)
Sufficient water quality Food availability (appropriate surface cover)
Sexually mature females FRS Radice and Loftus 1995, p. 114 Loftus and Trexler 2004, pp. 39-40, 45-48 Juveniles (post-release from female)
< 8 mm CL Freshwater availability (water quantity)
Sufficient water quality Food availability (appropriate surface cover)
Structural complexity of limestone deposits FS Hobbs 1971, pp.
116, 121 Loftus and Trexler 2004, pp. 39-40, 45-48 Adults Females and form I and II males 8 mm CL Freshwater availability (water quantity)
Sufficient water quality Food availability (appropriate surface cover)
Structural complexity of limestone deposits FRS Hobbs 1971, pp.
116, 121 Radice and Loftus 1995, pp. 114, 116 Loftus and Trexler 2004, pp. 39-40, 45-48 Exhibit 16
25 2.7.2. Population and Species Needs Resiliency (Population Needs)
Resiliency (measured at the population level) is the foundational building block of the SSA Framework. For Miami cave crayfish to be viable, some proportion of its range must be resilient enough to withstand stochastic events. Stochastic events that have the potential to affect Miami cave crayfish populations include karstic habitat modification, shifts in freshwater quality and/or quantity, and changes in surface cover that impact nutrient flow into the aquifer system.
Environmental stochasticity acts at local and regional scales; thus, the health of populations in any one year can vary over geographical areas (Hanski 1999, p. 372). For this reason, having populations distributed across a diversity of environmental conditions reduces the likelihood of concurrent losses of populations at local and regional scales.
For populations to be resilient, they need healthy demography (i.e., stable or positive growth rates), habitat that provides connectivity to allow for gene flow among subpopulations, and sufficient habitat quality and quantity to support healthy individuals. We have limited information regarding the population demographics of wild Miami cave crayfish. Subterranean taxa are generally reported to be present at lower abundances than their surface-dwelling equivalents due to abiotic constraints, such as low concentrations of nutrients, reduced levels of dissolved oxygen, and limited availability of space (Loftus and Trexler 2004, p. 49; Hancock et al. 2005, pp. 103-105). However, the low detectability of groundwater invertebrates can result in their incomplete sampling being confused with rarity and/or reduced population density. In fact, subterranean aquifer species exhibit a wide range of population sizes (Hutchins et al. 2020, p.
3980). Limited surveillance (both historical and current) compounded by low sampling efficacy precludes estimation of Miami cave crayfish abundance across the species range such that we are unable to determine the parameters of a demographically-healthy population with any confidence.
Due to the lack of demographic data, we do not know what the Miami cave crayfish needs to have a healthy demography. Therefore, we assume that fulfilling the resource needs for the species will result in healthy demography and resiliency. A number of factors influence whether Miami cave crayfish populations will grow to maximize habitat occupancy, which increases the resiliency of a population to stochastic events. These factors overlap with those that fulfill the life history and resource needs of individual Miami cave crayfish (Table 2.7.1) and include: 1.
freshwater availability (water quantity), 2. sufficient water quality, 3. karstic limestone substrate with interconnected megaporosities, and 4. food availability.
If Atlantic Coastal Ridge ecosystems provide adequate freshwater, sufficient water quality, and suitable habitat, we anticipate Miami cave crayfish populations will exhibit a high degree of resilience (Figure 2.7.2). However, given the relatively narrow range of the species, stochastic events could affect all Miami cave crayfish throughout their endemic range in any given time period. Therefore, the species is inherently vulnerable to adverse stochastic events.
Exhibit 16
26 Figure 2.7.2. Factors influencing the resiliency of Miami cave crayfish populations.
Redundancy (Species Needs)
Redundancy reflects the ability of a species to withstand natural or anthropogenic catastrophic events and is best achieved by having multiple, widely distributed populations relative to the spatial occurrence of catastrophic events. In addition to guarding against a single or a series of catastrophic events extirpating the entire species, redundancy is important to protect against losing irreplaceable sources of adaptive diversity (Carroll et al. 2010, entire; Redford et al. 2011, entire). Historically, Miami cave crayfish was, and still is, range-restricted. Therefore, any catastrophic event would likely impact the entire range. Consequently, Miami cave crayfish needs to have as much high-quality habitat as possible to retain the minimal redundancy the species exhibited historically and has currently.
Exhibit 16
27 Representation (Species Needs)
Representation is a function of both genetic and adaptive diversity. Genetic diversity is important because it can delineate evolutionary lineages that may harbor unique genetic variation, including adaptive traits. It can also be indicative of gene flow, migration, and dispersal.
Ecological diversity is important because it provides the variation in phenotypes and ecological settings on which natural selection acts. In addition, the processes that drive evolution (gene flow, natural selection, mutations, and genetic drift) are required to maintain species-level representation (Crandall 2000, p. 291). It is unknown whether Miami cave crayfish populations exhibit significant variation in genetic, morphologic, and/or ecological diversity. However, maintaining representation in the form of any genetic, phenotypic, or ecological diversity present is important to the capacity of the Miami cave crayfish to adapt to future environmental change.
CHAPTER 3 - INFLUENCES ON VIABILITY In this chapter, we evaluate the past, current, and future sources and influences that are affecting or could be affecting the current and future conditions of Miami cave crayfish. We also address factors for which we have little to no information related to their impact on Miami cave crayfish, but which may plausibly have an effect on the species currently or in the future (e.g., predation, competition, disease). From these factors and processes, we draw the influences that we will carry forward into our analyses of the current and future conditions of Miami cave crayfish.
3.1 Modification of Surface Cover The subterranean communities supporting Miami cave crayfish are dependent on the influx of detritus from surficial sources (Sections 2.4 and 2.5.2). When surface vegetation is lost or is blocked by impermeable land cover from entering subterranean habitats, the food supply of the species is significantly compromised. Development of the landscape, agricultural practices, and limestone extractive activities all directly contribute to the modification of surface cover across the endemic range of Miami cave crayfish. The effects of water management programs, land conservation initiatives, and climate change-related processes serve to further alter the presence of natural vegetative communities and the capacity for detrital filtering into groundwater on the Atlantic Coastal Ridge.
3.1.1 Development Exhibit 16
28 We use the term development to refer to urbanization of the landscape, including (but not necessarily limited to) land conversion for urban and commercial use, infrastructure (roads, bridges, utilities), and urban water uses (water supply reservoirs, wastewater treatment, etc.). As of April 1, 2020, Miami-Dade County was one of the most populous counties in the United States with a population of 2,701,767, an increase of 8.8 percent since 2010 (U.S. Census Bureau 2021, unpaginated). The majority of Miami-Dade countys residents are concentrated in urban sprawl stretching across approximately 598 square miles (1,550 square kilometers), mostly along the Atlantic Coastal Ridge (Bradner et al. 2005, p. 3) (Figure 3.1.2). Development in the county is anticipated to rise into the future in conjunction with burgeoning human populations, and approximately 6,718 acres (27 square kilometers) that overlay Miami cave crayfish habitat have already been identified to accommodate the urban expansion for the approximately 3,343,700 people who will be residing in the county within the next twenty years (Carr and Zwick 2016, p.
30; Miami-Dade County Department of Regulatory and Economic Resources 2021, pp. 2-5)
(Table 3.1.1). Accordingly, the direct and indirect threats associated with development affect the viability of not only current populations of Miami cave crayfish, but future ones as well.
Table 3.1.1. Projected population for Miami-Dade County from the end of 2020 to 2070. From Carr and Zwick (2016, p. 30).
Year 2020 2030 2040 2050 2060 2070 Population 2,796,800 3,090,200 3,343,700 3,646,040 3,930,968 4,215,896 Land use activities characterizing development result in the expansion of impervious surface cover and the removal of vegetation and other natural sources of detrital input into subterranean ecosystems. Hard surfaces, such as roofed buildings, paved roads, parking lots, and highly-compacted soils (e.g., of sports fields or unpaved airport runways), prevent the natural soaking of rainwater into the ground (Brabec et al. 2002, pp. 499-500; Hughes and White 2016, p. 10).
Instead, the precipitation accumulates and flows rapidly into storm drains and canal systems (Brabec et al. 2002, pp. 499-500; Hughes and White 2016, p. 10), carrying any mobile surface detritus along with it. The majority of the surface cover overlying the endemic range of Miami cave crayfish habitats consists of developed land, which is unlikely to provide adequate detrital input into the groundwater ecosystems below to sustain viable populations of the species (Figure 3.1.2).
In the future, adverse effects from climate change, dropping agricultural land values, and growing demand for residential space is anticipated to drive the conversion of a large amount of Miami-Dade Countys agricultural holdings to urban development (Carr and Zwick 2016, p. 30; Quaye et al. 2018, entire; Miami-Dade County Department of Regulatory and Economic Resources 2021, pp. 2-5). Such landscape use conversions have been demonstrated to drastically increase impervious surface runoff and decrease infiltration to groundwater reserves (Bonta 2013, entire).
Exhibit 16
29 Figure 3.1.2. Coverage of Miami-Dade County by Built Area (red) per Esri 2020 Land Use/Land Cover (Esri 2021). Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS from data provided by Esri 2021.
3.1.2 Agriculture Land use directly related to agricultural activities accounts for approximately 36,825 acres (14,902.5 hectares (ha)) of surface cover extending across the endemic range of Miami cave crayfish (Miami-Dade County. 2021a) (Figure 3.1.3; Appendix B). The vast majority of this Exhibit 16
30 agriculture (~97 percent) falls into the category of plant agriculture, which is dominated by winter vegetables, nursery ornamentals, and citrus and other tropical fruits. Animal agriculture (e.g., poultry, livestock, horses), aquaculture, and farm storage areas supporting agricultural activities only cover about 3 percent of the total agricultural acreage overlying Miami cave crayfish habitat (Figure 3.1.4; Appendix B). Although all populations of the species experience the effects of agricultural land use, analysis units 1, 2, and 3 are the most affected with total agricultural surface coverages of 12,074.30 acres (4,886.3 ha), 16930.41 acres (6,851.5 ha), and 7,651.41 acres (3,096.4 ha), respectively (Figure 3.1.3; Appendix B).
Exhibit 16
31 Figure 3.1.3. Agricultural land use in Miami-Dade County. Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS from data provided by Miami-Dade County 2021a.
Exhibit 16
32 Figure 3.1.4. Agricultural land use in Miami-Dade County by category per Miami-Dade County 2021a.
Similar to urbanization, agricultural activities require infrastructure that expands impermeable surface cover. The following agricultural structures all contribute significantly to the growth of impervious surface and loss of natural vegetative cover across the Miami cave crayfish range:
animal housing facilities; farm equipment storage areas; agricultural product processing, storage, shipping, and sales buildings; aquaculture tanks and pools; and horse training rings, pens, tracks, and pavilions (Figure 3.1.5).
97%
2%
<1%
1%
Coverage (in Acres) of Agricultural Land Use Plant Agriculture Animal Agriculture Aquaculture Farm Storage Exhibit 16
33 Figure 3.1.5. Examples of agricultural land uses contributions to loss of detrital input into Biscayne Aquifer ecosystems. A, Aerial view of the Atlantic Sapphire construction site, west looking east, near Homestead, Florida. When completed, it will occupy approximately 380,000 square feet (35,303 square meters). Overlays analysis unit 2. Photograph from Dahlberg (2018, unpaginated). B, Poultry barns at Morris Hatchery, Goulds, Florida. Overlays analysis unit 2.
Photograph © Morris Hatchery Inc. C, Horse training pen at Miami International Riding Club.
Overlays analysis unit 3. Photograph from http://www.mirc-horses.com/.
One of the most widespread irrigation practices in South Florida croplands is the use of irrigation trucks to spray fields. Along with the use of other agricultural machinery (e.g., plows, picker and harvester trucks, transportation vehicles), this irrigation method serves to mechanically compact soil in agricultural areas, leading to the loss of permeability in the substrate (Bonta 2013, pp.
1349, 1357). Similarly, trampling by livestock and horses contributes to soil compaction (Bonta 2013, pp. 1349, 1357) and the creation of impervious surfaces throughout the range of Miami cave crayfish, which hinders the downward flow of detritus into their aquifer habitats.
Rock-plowing is the process of using a bulldozer for scraping and crushing the surface layer of limestone such that natural detritus is mixed in and creates a soil layer. This soil layer facilitates the planting of row crops and, in areas where deeper excavation is permitted by lower water tables, tree crops (Li 2001, p. 1). Since the early 1950s, rock-plowing has been employed to varying degrees throughout the agricultural settings overlying the endemic range of Miami cave crayfish, reducing the filtration capacity of the surface layer generated by the practice (Li 2001,
- p. 1).
3.1.3 Anthropogenic Modification of Detrital Input Anthropogenic land use further serves to curtail the amount and quality of detrital influx into the Biscayne Aquifer by altering the type, quantity, and temporal distribution of vegetation that Exhibit 16
34 remains as surface cover in agricultural and developed regions. Post-colonial introductions of non-native plants have led to the spread of alien invasive species throughout south Florida (Stys et al. 2017, p. 363). For the purposes of this SSA, we define alien invasive species as an alien species (i.e., a taxon occurring outside of its natural range and dispersal potential) that becomes established in natural or semi-natural ecosystems, is an agent of change, and threatens native biological diversity per the Invasive Species Specialist Group (ISSG; 2000, pp. 5-6).
There are dozens of terrestrial alien invasive plants that range across the surface area above Miami cave crayfish habitat. Over twenty species are on the U.S. Department of Agricultures federal and state noxious weeds list (Hunsberger and Pena 2019, p. 1), while two taxa of alien invasive trees (Australian pine (Casuarina equisetifolia) and portia tree (Thespesia populnea))
that are not on the state noxious weeds list are widespread in Miami-Dade County (EDDMapS 2021, unpaginated). In their replacement of the native floral community, these alien invasive species alter not only the quantity but the type of detrital input that filters into subterranean ecosystems.
Many of the residential and commercial plantings in the Miami-Dade County area also consist of non-native species of plants (Degner et al. 2001, p. 3; USDA 2017, p. 2; Hunsberger and Pena 2019, pp. 1, 4). Plant agriculture in Miami-Dade County depends predominantly on non-native species, with the majority of acreage devoted to vegetables (tomatoes, squash, potatoes), nursery stock (e.g., foliage, potted flowering plants, woody ornamentals, bedding and garden plants, cut flowers), snap beans, avocados and sweet corn (Degner et al. 2001, p. 3; USDA 2017, p. 2).
Other key fruit crops include various citrus, carambola, longan, mamey sapote, mango, lychee, and strawberries (Degner et al. 2001, p. 3). It is unknown what variations might exist in the nutritional content of native vegetation versus that of the exotic plants that currently dominate the urbanized and agricultural landscape of the Atlantic Coastal Ridge. Any potential differences in the nutritional quality of detrital input into aquifer systems may have adverse or beneficial effects on Miami cave crayfish and/or their small crustacean prey.
The patterns in timing and amount of any persisting detrital influx into groundwater systems is also altered by human management of surficial vegetation. The seasonal growth and reproduction of native flora are adapted to predictable annual fluctuations in precipitation patterns. South Florida experiences a dry season from November through April followed by a wet season from May through October (Prinos et al. 2014, p. 7; Sukop et al. 2018, p. 1670). The most significant seasonal rainfall comes in the form of intense, fast-moving, and localized thunderstorms during the wet season, with the largest single precipitation events attributed to tropical storms and hurricanes (Sukop et al. 2018, p. 1670). Starting around 1900, human irrigation of agricultural and ornamental plants in the Miami-Dade County region decoupled this flora from rainfall constraints, which altered the temporal patterns of organic deposition from these plants onto the ground below.
Similarly, the application of pesticides, herbicides, fungicides, and fertilizers boosted the growth of plants and, thus, the deposition of vegetative matter that, pending the presence of permeable surfaces, could filter downwards into the aquifer below. Human management of plants often Exhibit 16
35 creates local concentrations of vegetation at unnaturally high abundances, such as in cropfields and in ornamental gardens of residential yards. Such floral arrangements might lead to unnaturally high influxes of surficial detritus into the aquifer below, resulting in localized contamination with excess nutrients that could harm Miami cave crayfish in the area (see section 3.4).
In contrast, certain agricultural practices may eliminate sources of detrital input when the potential for precipitation-driven infiltration of the aquifer is at its highest. For example, crop fields, especially those producing corn, are often left fallow in the wet season (Potter et al. 2007,
- p. 1302). However, growers are currently being encouraged to plant cover crops during the off season to reduce groundwater contamination by herbicides, a practice that would increase the potential for year-round detrital input below crop fields if widely adopted in the future (Potter et al. 2007, entire). Accordingly, human management of surface vegetation may set up feast or famine dynamics of detrital input into the Biscayne Aquifer, the effects of which are unknown for Miami cave crayfish but likely vary based on the season, plants involved, and types of interventions employed.
3.1.4 Climate Change Effects The Intergovernmental Panel on Climate Change (IPCC) concluded that the evidence for warming of the global climate system due to human influence is unequivocal (IPCC 2014, p. 2; IPCC 2021, pp. 5-8). Numerous long-term and rapid climate changes have been observed in the atmosphere, cryosphere, oceans, and biosphere, including but not limited to widespread changes in precipitation amounts, global sea level rise, elevated ocean salinity and acidification, and increases in the number and intensity of extreme weather events (e.g., droughts, heat waves, tropical cyclones) (IPCC 2014, pp. 2-4; IPCC 2021, pp. 5-11). The general climate trend for South Florida includes increases in mean annual temperatures, fluctuations in precipitation patterns, and the increased likelihood of extreme weather events by the mid-21st century (Alder and Hostetler 2013, unpaginated; IPCC 2014, pp. 1452-1456; Infanti et al. 2020, entire; IPCC 2021, pp. 32, 33) (Figures 3.1.6 and 3.1.7; Appendix C).
Climate change-driven fluctuations in both temperature and precipitation dynamics have influenced and will continue to alter the phenology (timing of seasonal activities) and viability of both native and non-native plants in the vegetative communities contributing surficial detritus to the habitats of Miami cave crayfish (Stys et al. 2017, pp. 358-359). Under both RCP 4.5 and RCP 8.5 scenarios, seasonal temperatures in Miami-Dade County are predicted to rise greater than 2F (RCP 4.5) or 4F (RCP 8.5) by 2074 (Alder and Hostetler 2013, unpaginated) (Figure 3.1.6). Plant species typically respond to rising temperatures with earlier leaf production and reproductive activity (e.g., flowering, fruiting) (Stys et al. 2017, p. 358), which will affect the temporal flux of surficial detritus into aquifer ecosystems. Temperature change and fluctuations in precipitation patterns will significantly impact floral community composition as well. While changing climatic parameters may be advantageous to some species, new boundaries of Exhibit 16
36 temperature and/or precipitation may have adverse or neutral effects on other plant taxa. The success of some plants and the extirpation of others modifies ecological interrelationships within the ecosystem (e.g., predator-prey, parasite-host, and competition dynamics), which influence what vegetation persists to provide detritus for subterranean habitats (Stys et al. 2017, p. 341).
Figure 3.1.6. Predicted mean temperature change in F (compared to 1981-2010 values) for Miami-Dade County, Florida per IPCC AR5s RCP 4.5 and RCP 8.5 for 2025-2049 (Top) and 2050-2074 (Bottom). Projections from Alder and Hostetler (2013, unpaginated).
Exhibit 16
37 Figure 3.1.7. Predicted mean monthly precipitation change in inches per month (compared to 1981-2010 values) for Miami-Dade County, Florida per IPCC AR5s RCP 4.5 and RCP 8.5 for 2025-2049 (Top) and 2050-2074 (Bottom). Projections from Alder and Hostetler (2013, unpaginated).
Even though carbon sinks on the land and in the ocean are predicted to store progressively greater amounts of carbon dioxide (CO2) under higher (compared to lower) emissions scenarios, these carbon sinks are highly likely to become less effective as CO2 emissions continue. As a result, the proportion of CO2 in the atmosphere will greatly increase (IPCC 2021, p. 25). Plants grown under elevated concentrations of CO2 generally use resources more efficiently than do plants growing at lower levels of CO2. Accordingly, the growth and biomass production of plants under higher concentrations CO2 are typically higher than those under ambient CO2 concentrations (Stys et al. 2017, p. 358). If the flora inhabiting the Atlantic Coastal Ridge respond analogously to higher CO2 levels, all else being equal, future rises in atmospheric carbon will lead to comparatively elevated vegetative biomass on the landscape and, thus, greater potential detrital influx into subterranean ecosystems. However, elevated CO2 may likewise impact the quality of the detritus filtering down into Miami cave crayfishs aquifer habitats.
Plants grown under elevated CO2 concentrations frequently exhibit decreased nitrogen concentrations and increased carbon:nitrogen ratios in their leaves, making them of lower quality for herbivore and omnivore consumers (Stys et al. 2017, p. 358).
3.1.5 Habitat Conservation Exhibit 16
38 Approximately 5,643 acres of land with some degree of protection overlaps the endemic range of Miami cave crayfish, accounting for 3.7 percent of the total surface area of the species endemic range (Figure 3.1.8; Appendix D). Protected lands vary in their level of protection from those with use restrictions (e.g., certain types of construction are prohibited in wellfields) to land that is actively managed to conserve its native biodiversity (e.g., Miami-Dade County-managed Bill Sadowski Park). Of that land, about 4,871 acres (1,971.2 ha) is publicly owned property (Appendix D). The majority of protected property along the Atlantic Coastal Ridge is managed by Miami-Dade County as public parks, which vary in the quality and amount of vegetation they preserve and the extent of impervious surface they contain onsite depending on the propertys use. For example, parks with a large extent of fitness zones, walkways, and playgrounds (e.g.,
Gratigny Plateau Park) contain less surface vegetation and more areas of impermeable land than do parks that conserve native vegetation (e.g., Bill Sadowski Park) and/or that highlight non-native flora (e.g., Preston B. Bird and Mary Heinlein Fruit & Spice Park).
The Natural Areas Management Division of Miami-Dade County Parks, Recreation, and Open Spaces Department is specifically responsible for the restoration of and alien invasive species removal on 98 natural preserves spread across the county (Miami-Dade County 2021d, unpaginated), management activities that promote the filtration of high-quality detritus to the aquifer ecosystems below. Although county-operated parks contribute to the surface land use above all populations of Miami cave crayfish, the greatest extent of county parkland overlaps the habitat of analysis unit 4 (1,642 acres, 664.5 ha) (Figure 3.1.8; Appendix D).
Exhibit 16
39 Figure 3.1.8: Extent of coverage of five types of protected land across the seven analysis units of Miami cave crayfish. Map drafted in GIS using the land use data for Miami-Dade County provided by the research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a). Categorizations are per Miami-Dade County (2021a). Other Nature Preserves and Protected Areas include state mangrove preserves, Turkey Point Wilderness Area, Big Cypress Swamp Preserves, and acquired government owned Environmentally Endangered Land (EEL) Covenant sites. Vacant, Protected, Government-Owned or controlled includes EEL sites. Vacant, Protected, Privately-Owned are privately-Exhibit 16
40 owned proposed and designated EEL sites that have yet to be acquired and/or sites protected under any other conservation or environmental mechanism. EEL sites that were classified as released or expired are not illustrated.
In addition to the park system, the conservation and restoration efforts of the county potentially adds more detrital input to aquifer systems through land management projects conducted on other county properties. Miami-Dade County adopted the Street Tree Master Plan in 2006.
The initiative aims to reach a 30 percent tree canopy covering in the county (equivalent of one million trees), targeting approximately 50 percent tree canopy in suburban areas, 25 percent in urban residential areas, and 10 percent in urban core areas. Miami-Dade County itself has committed to planting 300,000 trees on county land (Miami-Dade County 2007, entire; Miami-Dade County 2021e, unpaginated). However, it is unknown what benefit this planting effort will have for detrital input into Miami cave crayfish habitats since much of the surface cover below the trees is impervious.
Miami-Dade County also attempts to conserve forested land (outside of Everglades National Park) by providing private property owners with an economic incentive to preserve these native habitats via the Environmentally Endangered Lands (EEL) Tax Covenant Ordinance adopted in 1979. Under this program, a property tax reduction of 90 percent is given to forested sites that are otherwise zoned for agricultural or residential use. In exchange, landowners enter into a ten-year conservation agreement with the county, promising to preserve the hammock and/or pine forest assessed at the significantly reduced rate (Chapter 25B, Article II, of the Miami-Dade County Code as authorized by Section 193.501, Florida Statutes). In this manner, the county is able to conserve a portion of the areas threatened private holdings of native forest, which can serve as a source of natural vegetative detritus to the Miami cave crayfish below. Although analysis units 4, 6, and 7 do not benefit from the indirect effect of the EEL program, the remaining four analysis units exist below private lands protected by this county ordinance (Figure 3.1.8; Appendix D).
3.1.6 Summary of Modification of Surface Cover Miami cave crayfish are dependent on the influx of detritus from surficial sources. This input is blocked by impervious land cover that is associated with urbanization and agricultural practices.
Detrital influx can also be lost when vegetative surface cover is removed by these two predominant land use activities. Even in areas where plants persist, the quality, quantity, and timing of detrital input is altered by anthropogenic management of vegetation, the spread of alien invasive species, and climatic factors. Although some protected lands preserve native vegetation on the Atlantic Coastal Ridge, the small fraction of conserved areas cannot mitigate the obstruction of detrital flow by the impervious surfaces and compromised or extirpated vegetative communities across most of Miami-Dade County. Consequently, Miami cave crayfish are Exhibit 16
41 significantly and negatively impacted throughout their endemic range by the severe reduction of detrital input into the aquifer ecosystem.
3.2 Modification of Karstic Limestone The impact of anthropogenic land use activities goes deeper than surface cover alone.
Urbanization, agriculture, limestone extraction, and their supporting infrastructure alter and destroy the karstic limestone habitats inhabited by Miami cave crayfish, likely causing direct mortality of individual crayfish in the process. Roadways, building foundations, below-ground swimming pools, septic tanks, wells, utility infrastructure, pond excavations in suburban developments (often generating fill to elevate homesites), and an assortment of other anthropogenic structures are cut directly into the limestone of the Atlantic Coastal Ridge at varying depths, resulting in the destruction of key Miami cave crayfish habitat and the death of any individuals within the limestone that is removed or otherwise destroyed.
3.2.1 Subterranean Infrastructure The direct impact of subterranean excavation activities on Miami cave crayfish individuals in historical and current populations has been demonstrated for water well drilling activities.
Deceased and living Miami cave crayfish were reported from blowouts of limestone in the course of drilling in the 1990s and 2018 (Radice and Loftus 1995, p. 114; Cook et al. 2018, suppl.; Loftus pers. comm. 2021) (Figure 3.2.1). Tens of thousands of agricultural, domestic, and industrial water supply wells stretch across the species endemic habitat in Miami-Dade County, ranging in depth from a few feet to more than 121 ft (37 m) (Prinos et al. 2014, p. 18). The level of direct and indirect adverse effects of these installations on Miami cave crayfish populations is unknown but is expected to be significant.
Exhibit 16
42 Figure 3.2.1. Examples of commonly used drilling methods for water well placement. From van Lopik 2020 (p. 16).
One of the most extensive networks of subterranean karstic limestone destruction exists in the form of over 8,500 miles (13,679 km) of underground water lines and 4,100 miles (6,598 km) of sewer lines maintained by Miami-Dade County (Miami-Dade County 2021c, unpaginated)
(Figure 3.2.2). Miami-Dade County Water and Sewer Department sets current standards for the design and construction of sewer and water lines, which stipulate that new pipes must be accommodated by sufficient trenching above and to either side of the pipe to provide safe working conditions for laborers (Miami-Dade County Water and Sewer Department 1999, unpaginated).
Exhibit 16
43 Since sewer and water lines vary in width of pipe and depth of placement, the footprint of the infrastructure can range widely in any given region. In addition, all underground pipes must be placed on bedding material that is cut at least 6 inches deep into limestone since marl, muck, and organic matter are deemed unsuitable foundation material. Backfill of cement, concrete mix, sand, or other material of small diameter must be placed around the pipe in the excavated area such that the backfill material fills the cavities in the surrounding limestone (Miami-Dade County Water and Sewer Department 1999, unpaginated). This backfill contributes further to the destruction of the adjacent limestone habitat of Miami cave crayfish by filling in the interconnected networks of openings within the limestone and preventing the movement of water, nutrients, and crayfish through the substrate. In some areas, underground utility infrastructure may reduce connectivity of Miami cave crayfish populations or potentially isolate groups of individuals.
Exhibit 16
44 Figure 3.2.2. Miami-Dade County maintains 4,100 miles (6,598 km) of sewer lines (Miami-Dade County 2021c, unpaginated), many of which have been cut into the karstic limestone habitat of Miami cave crayfish. Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS from data provided by Miami-Dade County 2021c.
Exhibit 16
45 In the future, burgeoning urban sprawl and its attendant infrastructure will cause increased destruction of subterranean karstic limestone habitats and some direct mortality of Miami cave crayfish in new regions of the Atlantic Coastal Ridge. Expanding aquaculture facilities, particularly in the regions of analysis units 1, 2, 3, and 5, adding significantly to the already expansive network of underground infrastructure supporting agricultural lands. Illustrating the below ground imprint of aquacultural operations, the newly-constructed Atlantic Sapphire building in Homestead used an estimated 12,000 truckloads of crushed rock for its foundation and 60 miles (96.6 km) of pipeline for its 380,000 square foot (35,303 square meter) facility (Dahlberg 2018, unpaginated). Underground infrastructure will also require constant and long-term maintenance, especially in areas with high water tables and any degree of infiltration of corrosive saltwater (Trian and Carolan 2017, entire). The construction activities necessary for upkeep of subterranean structures will contribute further to the destruction and alteration of surrounding karstic limestone habitat of Miami cave crayfish and the direct mortality of individuals.
3.2.2 Limestone Extraction Limestone quarrying has contributed to the growth of Floridas extractive economy since the 1900s with current operations concentrated in Marion and Miami-Dade counties (Volk et al.
2017, p. 58). Limestone extracted from Miami Limestone deposits in Miami-Dade County are one of the highest quality, and thus highest in demand, in the nation and used primarily for bridge, building, and road construction (Miami Dade Limestone Products Association 2021, unpaginated; Volk et al. 2017, p. 58). Quarrying operations in the county produce over 60 million tons of the 139 million tons of limestone used by Florida alone for its construction projects (Miami Dade Limestone Products Association 2021, unpaginated). Limestone quarrying has been specifically cited as a significant threat to Miami cave crayfish exposed to these activities (Loftus and Trexler 2004, p. 50). Due to the destructive nature of the limestone excavation and extraction process, quarrying removes all Miami cave crayfish habitat in their areas of operation. Either gaping holes or lakes that fill the open pits are left behind after limestone removal (Figure 3.2.3).
Exhibit 16
46 Figure 3.2.3. Limestone quarrying operation in Miami-Dade County. Photograph by Miami-Dade Limestone Products Association.
At the present time, only analysis unit 2 is directly affected by ongoing limestone mining activities (Figure 3.2.4). Within this range, approximately 393 acres (159 ha) (extending to an unknown depth) of karstic limestone habitat has been lost from past and present extraction at two main sites (Figure 3.2.4; Table 3.2.1)
Exhibit 16
47 Figure 3.2.4. Limestone quarrying-related land use within the range of analysis unit 2 of Miami cave crayfish. Analysis unit boundaries for Miami cave crayfish are outlined in black for reference. Map drafted in GIS using the land use data for Miami-Dade County provided by the Exhibit 16
48 research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a). Categorizations are per Miami-Dade County (2021a).
Table 3.2.1. Impact of limestone extraction-related land use activities on Miami cave crayfish analysis unit 2 measured in total coverage (acres), total number of individual localities, and total number of sites within which those localities are located. Estimates calculated using the land use data for Miami-Dade County provided by the research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a). Categorizations are per Miami-Dade County (2021a).
Limestone Extraction-Related Land Use Coverage Number of Localities Extraction, Excavation, Quarrying, Rock-Mining, excluding the resulting water body.
80.4 acres (32.5 ha) 4 total, 2 sites Inland water bodies (Lakes, Rock Pits) associated with extraction, excavation, quarrying and rock-mining activities.
312.4 acres (126.4 ha) 3 total, 2 sites Combined 392.8 acres (159 ha) 7 total, 2 sites Future limestone and other mineral extraction activities are predicted to persist and expand primarily outside the current range of Miami cave crayfish in the "lake belt" region of northwestern Miami-Dade County (north of the Tamiami Trail and west of the turnpike extension) (Miami-Dade County Department of Regulatory and Economic Resources. 2020, p.
94). However, other regions of open land within the endemic range of Miami cave crayfish have been identified as areas that may be approved for future use as limestone quarries by 2030 (e.g.,
Open Land Subarea 5, which is located above analysis unit 2) (Miami-Dade County Department of Regulatory and Economic Resources. 2020, pp. 74, 77). Although limestone quarrying causes direct mortality and loss of karstic limestone habitat, the extractive activity is a relatively minor stressor for the species and is unlikely to pose a significant threat to future populations of Miami cave crayfish.
3.2.3. Karstic Limestone Preservation Although there are no specific preservation regulations or protection measures in place for subterranean karstic limestone habitats in Miami-Dade County, lands enrolled in the EEL program, managed as county parks, or within the bounds of other protected areas (section 3.1.4; Figure 3.1.8; Appendix D) are unlikely to be significantly impacted by loss of limestone. An exception would be in the case of Miami-Dade County-operated parks that undergo expansion of their underground infrastructure (e.g., additional water or sewer lines) or recreational waterbodies. The projected future expansion of urbanized areas into the open land remaining on Exhibit 16
49 the Atlantic Coastal Ridge (Carr and Zwick 2016, entire; Miami-Dade County Department of Regulatory and Economic Resources 2020, entire) constrains the expansion of limestone quarrying into these regions and, thus, serves a mitigating role in the preservation of subterranean karstic limestone.
3.2.4 Summary of Modification of Karstic Limestone Urbanization, agriculture, limestone extraction, and their supporting infrastructure damage and destroy karstic limestone habitats and cause direct mortality of Miami cave crayfish. There are no regulatory or protective measures in place that specifically protect limestone habitats. Despite the wide extent of karstic limestone modification, areas of complete destruction of habitat are isolated such that Miami cave crayfish are unlikely to be impacted by karstic limestone loss at the species level.
3.3 Aquifer Drawdown Residents of Miami-Dade County have been pumping freshwater out of the Biscayne Aquifer for residential, agricultural, industrial, municipal, and recreational use since the first public supply wells were drilled in 1899 (Prinos et al. 2014, p. 18; Hughes and White 2016, pp. 27-29). As the population has grown, so too has the demand for freshwater. Public groundwater withdrawals increased in line with population growth until 2006 after which time demand on the aquifer was mitigated by stricter water use regulations (Bradner et al. 2005, p. 1; Prinos et al. 2014, p. 7).
Although 90 percent of the freshwater consumed by Miami-Dade County residents is pumped from the Biscayne Aquifer, these are not the only South Florida populations drawing from the aquifers groundwater reserves. Over 4 million people in Broward and Palm Beach Counties also rely on the Biscayne Aquifer for their freshwater needs, and groundwater piped from the Biscayne Aquifer to the Florida Keys serves as the main source of potable water for all of Monroe County (Bradner et al. 2005, p. 1; Prinos et al. 2014, p. 7). Consequently, the U.S.
Environmental Protection Agency has designated the Biscayne Aquifer as a sole-source aquifer (i.e., the only viable groundwater source in the region).
The most recent comprehensive estimate for total withdrawals from the Biscayne Aquifer was for 2000 and predicted 812 million gallons were pumped per day, 698 million gallons of which were consumed directly by the public and 114 million gallons for agricultural irrigation (Bradner et al. 2005, p. 1; Maupin and Barber 2005, pp. 12, 38). Groundwater pumpage within Miami-Dade County at production wellfields alone ranged as high as 85 million gallons per day (Southwest wellfield) from 1996 through 2010 (Hughes and White 2016, p. 27).
When groundwater pumping rates exceed recharge rates for an aquifer, the levels of freshwater reserves drop (Potter et al. 2007, p. 1305). These deficits can be evidenced even on a small scale.
Exhibit 16
50 For example, total daily irrigation amounts on a cornfield in Miami-Dade County during the dry season were between 8.19 and 21 inches (208 and 533 mm), which were 0.9 to 3.8 times the total rainfall for the same period. As a result, the aquifer level measured in the closest irrigation borehole to the agricultural plot fell by about 0.01 inch (0.3 mm) (Potter et al. 2007, p. 1305).
The effects of freshwater pumpage from the Biscayne Aquifer are exacerbated by the proliferation of extensive impervious surfaces across developed areas. The infiltration of rainfall along the Atlantic Coastal Ridge serves as one of the primary recharge inputs for the Biscayne Aquifer system (Fish and Stewart 1991, p. 47; Fairbank and Hohner 1995, p. 22). The highest regional excess precipitation (i.e., rainfall minus evapotranspiration losses) values, and thus the greatest potential for aquifer recharge from rainfall, occur along the coastal portions of the Atlantic Coastal Ridge (Fairbank and Hohner 1995, p. 22) (Figure 3.3.1). However, impervious surfaces in the urbanized areas of this region prevent the natural seepage of rainwater into the Biscayne Aquifer below (Brabec et al. 2002, pp. 499-500; Hughes and White 2016, p. 10).
Consequently, the highest recharge areas on the Atlantic Coastal Ridge are located in undeveloped and rural regions (Fairbank and Hohner 1995, p. 22) (Figure 3.3.2). As urban sprawl and its impervious surfaces continue to expand, the recharge potential from rainfall will continue to plummet, decreasing the natural refilling capacity of the Biscayne Aquifer system and contributing to the loss of Miami cave crayfishs groundwater habitats along the Atlantic Coastal Ridge.
Exhibit 16
51 Figure 3.3.1. Excess precipitation (i.e., rainfall minus evapotranspiration losses) values estimated in inches per year for Miami-Dade County. Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS with data provided by South Florida Water Management District (2018).
Exhibit 16
52 Figure 3.3.2. Estimated recharge of the Biscayne Aquifer from precipitation. Values reported in inches per year. Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Note the discrepancy between the estimated precipitation recharge values as depicted above and the potential recharge from the excess precipitation values illustrated in Figure 3.1.1. Map drafted in GIS with data provided by South Florida Water Management District (2020).
Exhibit 16
53 As a result of groundwater pumpage and compromised recharge dynamics, water levels in the Biscayne Aquifer in the Atlantic Coastal Ridge are estimated to have fallen approximately 9.5 ft (2.9 m) below pre-drainage of the Everglades conditions (Prinos et al. 2014, p. 17). Assuming a surface area of 6,593,057,928.68 square feet (612,515,124.47 square meters) of potential Miami cave crayfish habitat on the Atlantic Coastal Ridge, freshwater depletion of the Biscayne Aquifer has translated into a loss of about 59,337,521,358 cubic feet (1,680,251,489 cubic meters) or 11 percent of potential Miami cave crayfish habitat since the 1840s (calculated on the basis of current habitat quantity; see Appendix E for details).
In addition to the direct loss of habitat for the species, aquifer drawdown affects flow dynamics within the Biscayne Aquifer, which can impact water quality (e.g., dissolved oxygen levels) and the circulation of nutrients within the system (Fish and Stewart 1991, p. 47; Hancock et al. 2005, pp. 104-105; Wacker et al. 2014, pp. 27-40). As of 2011, reduction in freshwater levels has also been responsible for the intrusion of approximately 12,916,692,500 square feet (1,200 square kilometers) of saltwater into the Biscayne Aquifer in Miami-Dade County (Bradner et al., 2005,
- p. 3; Prinos et al. 2014, p. 17). This saltwater intrusion further reduces the habitat available for use by Miami cave crayfish on the Atlantic Coastal Ridge (see section 3.5 for detailed discussion of saltwater intrusion of the Biscayne Aquifer).
3.3.1. Direct Mortality from Groundwater Pumping Miami cave crayfish are impacted by direct mortality from the groundwater pumping process as well. Water pumps depend on centrifugal force created by impellers (spinning rotors) to create a vacuum that draws water upwards through the well casing and into a distribution system (Figure 3.3.3). Miami cave crayfish inhabiting the adjacent aquifer can get sucked into the water pump system and macerated by the spinning impellers. Any individuals fortunate enough to survive the spinning rotors will be deposited either in filtration traps attached to the pump system or forced out with the pumped water via the water distribution system. In either case, the Miami cave crayfish are unlikely to survive for any significant period of time (Hobbs 1971, p. 114; Loftus pers. comm. 2020). In fact, the original specimens from which the species was first described were deceased individuals collected from a water pump trap (Hobbs 1971, p. 114).
Exhibit 16
54 Figure 3.3.3. Diagram of water well system (left) with detailed view of water pump with impeller (right).
3.3.2 Climate Change and Aquifer Drawdown As reviewed in section 3.1.4, climate change is projected to significantly elevate temperatures and alter precipitation patterns in Miami-Dade County in the future. Currently, water levels within the Biscayne Aquifer in Miami-Dade County reach their minimum levels following peak air temperatures and/or periods of drought (Prinos et al. 2014, pp. 2, 18, 20, 55, 65; Prinos and Dixon 2016, p. 26). As temperatures rise (Figure 3.1.6), so too do the rates of evapotranspiration (water loss from the land to the atmosphere via evaporation from the soil and transpiration from plants) and evaporation from waterbodies (e.g., recreational lakes maintained by the county park system, public and private pools, suburban ponds, open air aquaculture tank systems). As a result, demand for groundwater from the Biscayne Aquifer to counter these increasing water losses are anticipated to rise for residential, agricultural, industrial, municipal, and recreational uses. The predicted increase in the frequency, duration, and intensity of droughts in south Florida (Figure 3.17; Appendix C) will concurrently lead to elevated freshwater withdrawal from the aquifer system, largely for irrigation purposes.
Increased levels of precipitation during the wet season and from more frequent and intense typhoonal storm systems in the future (Figure 3.1.7; Appendix C) might mitigate the effects of aquifer drawdown by elevating the rate of aquifer recharge. Current high water levels in the Biscayne Aquifer on the Atlantic Coastal Ridge correlate with the seasonal wet season, and large rainfall events (i.e., greater than 1 inch (25.4 mm) per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) elevated the water table by up to 2.5 times the total depth of precipitation from the storm event (Potter et al. 2007, p. 1305).
However, major rainfall events quickly saturate soil across the Atlantic Coastal Ridge (Potter et al. 2007, p. 1304), which will contribute to significant run-off rather than extensive areas of infiltration in the presence of the impervious surfaces that will likely dominant the surface area of Miami-Dade County in the future (section 3.1.1).
Exhibit 16
55 3.3.3 Water Regulations The South Florida Water Management District is responsible for water management in Miami-Dade County and regulates water use and production throughout the region. In 2007, South Florida Water Management District passed a rule that prevents water consumers from sourcing new or additional supplies of freshwater that are recharged by the Everglades ecosystem. Water users are now required to use alternative sources, such as recycled water, treated wastewater pumped into the Biscayne Aquifer for recharge purposes, groundwater reserves in the Floridan aquifer system (Figure 2.5.1), or general water conservation practices (South Florida Water Management District 2008, entire; Hughes and White 2016, pp. 2-3). The measure has already resulted in decreased rates of public water withdrawal from the Biscayne Aquifer (Bradner et al.
2005, p. 1; Prinos et al. 2014, p. 7).
Another key regulation adopted by South Florida Water Management District that counters freshwater withdrawal from the Biscayne Aquifer is its year-round landscape watering restrictions (Chapter 40E-24, Florida Administrative Code). These restrictions stipulate specific times that landscape watering is permitted, thus restricting the amount of groundwater that can be withdrawn from those using public or privately-owned water utility systems or wells.
However, some large sources of water consumption are exempted by these regulations, namely athletic play areas (e.g., golf courses, sports facilities, equestrian and livestock arenas),
agricultural operations with consumptive use permits, and water users practicing hand watering (e.g., with hoses) (South Florida Water Management District 2021a, unpaginated).
South Florida Water Management District also promotes voluntary groundwater conservation through its Comprehensive Water Conservation Program, which combines voluntary and incentive-based initiatives and public education. Since its implementation in 2000, the program boasts an estimated reduction of 52 gallons of water per day per person as a result of its passive measures (e.g., backing water efficiency improvements in household appliances and irrigation systems) (SFWMD 2021b, unpaginated).
3.3.4. Summary of Aquifer Drawdown Groundwater pumping for residential, agricultural, industrial, municipal, and recreational use, and reduction in recharge capacity from impervious surfaces has lowered the level of fresh water in the Biscayne Aquifer. Climatic processes and population growth exacerbate aquifer drawdown in the region, which contributes to saltwater intrusion. South Florida Water Management District attempts to reduce freshwater withdrawals from the aquifer system via regulation and promotion of voluntary water conservation programs. The significant loss of groundwater reserves and its contribution to increased saltwater intrusion destroys the freshwater habitat on which Miami cave crayfish depend. Pumping can also cause direct mortality of individuals. For this reason, we determine that aquifer drawdown poses a significant threat to the species.
Exhibit 16
56 3.4 Groundwater Contamination by Anthropogenic Sources The high permeability of the Biscayne Aquifer, particularly along the Atlantic Coastal Ridge, makes its groundwater vulnerable to contamination from surficial inputs, belowground septic tanks, and adjoining water bodies (Bradner et al. 2005, entire; Potter et al. 2007, p. 1306; Florida Department of Environmental Protection 2019) (Figure 3.4.1). In particular, the sandy soils typical to the Atlantic Coastal Ridge contain relatively small amounts of soil organic matter and exhibit low water retention, increasing the potential for leaching of surface contaminants into groundwater below (March et al 2016, pp. 237-238). Additionally, the high interconnectivity of the Biscayne Aquifer facilitates the relatively rapid and extensive spread of contaminants well beyond their point of origin (Harvey et al. 2008, entire; Shapiro et al. 2008, entire).
Exhibit 16
57 Figure 3.4.1. A relative vulnerability map for the contamination potential of the Biscayne Aquifer in South Florida developed by the Florida Department of Environmental Protection (FDEP). Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS with data provided by FDEP (2019).
Exhibit 16
58 Water pollutants can be classified into five main categories: 1. pharmaceuticals, such as antibiotics, beta-blockers, lipid regulators, antidepressants, hormones, analgesics, and recreational drugs, 2. pesticides, such as herbicides, insecticides, fungicides, 3. volatile organic compounds, such as components of petroleum products, solvents, refrigerants, and fumigants, 4.
excess nutrients, usually nitrogen and phosphorus, and 5. excess trace elements, such as heavy metals like arsenic, copper, and lead. The distribution and concentration of these anthropogenic contaminants vary throughout the endemic range of Miami cave crayfish based on the type of pollutant, the source of the pollutant, the amount of the pollutant introduced into the aquifer system, and seasonal variations in water flow dynamics.
3.4.1 Contaminant Effects on Miami Cave Crayfish Contaminants influence the mortality and morbidity of animals differently based on: 1. the type of pollutant, 2. the exposure dynamics (e.g., dose of exposure, duration of exposure, number of exposures), 3. the biological state of the individual exposed (e.g., reproductive condition, immune condition, age, size), and 4. co-exposure to other contaminants, whose interactive effects may be cumulatively or synergistically adverse or even neutralizing when combined (Newman 2015, pp.33-304; Abdulelah et al. 2020, pp. 4, 5).
Although no ecotoxicological research has been conducted specifically on Miami cave crayfish, we use other crayfish taxa and crustaceans as analogues to assess the potential impact of groundwater pollution on individuals. On the basis of other crustacean models, we determine that the most likely effects of pharmaceuticals, pesticides, volatile organic compounds, and excess trace elements include (but are not necessarily limited to): 1. loss of chemoreception and behaviors dependent on chemoreception, such as recognizing conspecifics, mating and other social interactions, foraging, and identifying predators, 2. retardation of growth at various life stages, including alterations in molting, 3. structural changes to organs, particularly gills, and other acute and chronic physiological damage, 4. endocrine disruption at all life stages, 5.
inhibited development of sex organs in juveniles and DNA damage in spermatozoa of adults, 6.
reduction in lifespan, and 7. mortality (Nicosia et al. 2014, entire; Belanger et al. 2016, pp. 639-642; Loughlin et al. 2016, pp.98-101; Belanger et al. 2017, pp. 558-559; Silveyra et al. 2018, pp.
138-141; Stara et al. 2018, pp. 97-99; Steele et al. 2018, entire; Alcorlo et al. 2019, entire; Abdulelah et al. 2020, pp. 2, 4, 5; Marçal et al. 2020, entire). These responses to water contaminants have significant enough direct and indirect effects on morbidity, mortality, and reproductive success such that the adverse effects can be upscaled to the level of population and analysis unit with confidence (Abdulelah et al. 2020, p. 5). While detrimental physiologically and behaviorally, crayfish reactions to excess nutrients are typically short-lived and relatively minor in comparison to those evidenced in response to pharmaceuticals, pesticides, volatile organic compounds, and heavy metals (Jenson 1996, pp. 102, 103; Broughton et al. 2018, p. 937; Edwards et al. 2018, entire).
Exhibit 16
59 3.4.2 Predicted Exposure of Miami Cave Crayfish to Contaminants Specific areas of groundwater contamination or likely contamination have been identified recently in the endemic range of Miami cave crayfish by both state and federal environmental agencies (Figure 3.4.2). The Florida Department of Environmental Protection identified a Groundwater Contamination Area, which represents a region of confirmed anthropogenic pollution (contaminant unspecified) within the Biscayne Aquifer (FL DEP 2019, unpaginated).
This location is within the range of analysis unit 7. Homestead Air Force Base, which sits atop analysis unit 2, was placed on the Superfund National Priorities List by the U.S. Environmental Protection Agency on August 30, 1990. State and federal groundwater standards were exceeded due to historical onsite disposal of pollutants related to the operation and maintenance of aircraft and other facility-related maintenance activities, including pesticides and volatile organic compounds. Despite an on-going clean-up effort, groundwater continues to test above acceptable state and federal safe values (US EPA 2021, unpaginated). Several sites within the Miami cave crayfish endemic range have been listed as impaired surface waters by the Florida Department of Environmental Protection, most notably two locations overlapping analysis unit 7 that are contaminated by excess heavy metals and excess nutrients (FL DEP 2021, unpaginated). Due to the high connectivity of surface water and groundwater in this region, it is highly likely that the aquifer in these areas is also contaminated by copper and excess nutrients.
Exhibit 16
60 Figure 3.4.2. Areas of confirmed and probable groundwater contamination of the Biscayne Aquifer in the endemic range of Miami cave crayfish. US EPA = U.S. Environmental Protection Agency. FL DEP = Florida Department of Environmental Protection. Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS with data provided by FDEP (2021) and US EPA (2021).
Exhibit 16
61 A current and comprehensive regional assessment of groundwater contamination across the endemic range of Miami cave crayfish is not available. Human wastewater (especially that discharged by septic systems and sewer overflows), fertilizers, animal wastewater (e.g., runoff from animal agricultural operations), and direct aquacultural flow through discharge into the aquifer are responsible for concentrated groundwater contamination with pharmaceuticals, pesticides, excess nutrients, and excess trace elements (Bradner et al. 2005, pp. 8, 10; Potter et al.
2007, entire; Giddings et al. 2009, p.2; Bringolf et al. 2010, p.1311; Nicosia et al. 2014, pp. 14, 19; March et al 2016, pp. 237-238; Kazakova et al. 2018, pp. 144-145, 150; Zhang et al. 2019, p.
1). Plant agricultural operations, landscaping activities (e.g., lawncare, park maintenance), and golf courses are largely responsible for the introduction of pesticides, volatile organic compounds, excess nutrients, and excess trace elements into the Biscayne Aquifer (Miles and Pfeuffer 1997, p. 337; Bradner et al. 2005, p. 10; Harman-Fetcho et al. 2005, pp. 6042, 6047; Belanger et al 2016, p. 636). The primary sources of volatile organic compounds and excess trace elements include industrial areas (particularly in the older and denser industrial areas of Miami-Dade County), roadways and right of ways, railroads, gas stations, oil and gas storage facilities, and airports (Vincent 1984, entire; Bradner et al. 2005, pp. 11, 14).
Anthropogenic contaminants concentrate in waterbodies, particularly canals, on the Atlantic Coastal Ridge (Harman-Fetcho et al. 2005, entire; Potter et al. 2007, p. 1306; Bargar et al. 2017, entire). Relatively open exchanges of water between the aquifers groundwater system and canals and other water bodies typifies the hydrology of the region. As a result, a wide variety of concentrated contaminants infiltrate the Biscayne Aquifer where it comes into contact with surficial waterways, dissipating extensively within the highly permeable groundwater system (Potter et al. 2007, p. 1306; Bargar et al. 2017, p. 530). For a more detailed description of groundwater contamination in the Biscayne Aquifer of Miami-Dade County, refer to Miles and Pfeuffer (1997), Bradner et al. (2005), Pfeuffer (2009), and Pfeuffer (2011).
3.4.3 Special Case: Radiation Miami cave crayfish face a unique influence in regards to anthropogenic water contamination as a result of the proximity of the Turkey Point Nuclear Power Plant to their endemic range (Figure 3.4.3). The two reactors of the facility were constructed between 1972 and 1973 and are cooled by an approximately ten square mile (26 square km) canal network that stretches across almost 6,000 acres (Chin 2016, entire). Water in the cooling canals is reported to have tritium concentrations at least two orders of magnitude above that of adjacent surface waters (Janzen and Krupa 2011, p. 8). Exposure to ionizing radiation from tritium and other radioactive isotopes causes radiation toxicity (i.e., radiation poisoning). Tritium leaks into the surrounding Biscayne Aquifer such that the tritium concentration of groundwater samples collected from sites located within 5.3 miles (8.5 km) of the canal system ranged from 4.1 to 53.3 Tritium Units (within safe drinking water limits) (Prinos et al. 2014, p. 47). Due to the high connectivity of the Biscayne Aquifer system, it is possible that current Miami cave crayfish populations in the southeastern portion of the species endemic range are exposed to some degree of tritium contamination of their freshwater habitats (Figure 3.4.3).
Exhibit 16
62 Figure 3.4.3. Turkey Point Nuclear Power Plant with 10-mile radius, 50-mile radius, and radioactive plume pathway illustrated. Boundaries for the seven analysis units of Miami cave crayfish are outlined in black for reference. Map drafted in GIS with data provided by Miami-Dade County (2021g).
Exhibit 16
63 Despite its aging infrastructure, two of the facilitys reactors gained a 20-year subsequent renewed license in 2018 (U.S. Nuclear Regulatory Commission 2016, entire). As illustrated by the nuclear accident at Fukushima Daiichi Nuclear Power Plant in Japan, the effects of severe weather and rising sea levels increase the threat of nuclear incidents (Fuller et al. 2015, p. 56).
This risk of a natural disaster-related incident at Turkey Point Nuclear Power Plant will only grow as regional sea level rises and climate change elevates the number and intensity of severe weather events in the area (section 3.1.4).
In the event of a serious nuclear catastrophe (e.g., a partial or complete meltdown incident), the area within a ten-mile radius of the reactor site is expected to experience severe effects, including unbreathable air, whereas an extended region within a 50-mile radius of the reactor site is predicted to experience severe radioactive contamination, notably of its food and water supplies (U.S. Nuclear Regulatory Commission 2021, unpaginated). In the case of Turkey Point Nuclear Power Plant, Miami-Dade Countys Office of Emergency Management has specifically mapped the areas anticipated to receive radioactive fallout from a plume generated by a nuclear accident at either or both of the plants reactors (Miami-Dade County 2021g, unpaginated) (Figure 3.4.3).
If a nuclear accident were to occur at the Turkey Point facility, analysis units 1, 2, 3, 4, and 5 would all be exposed to extremely high levels of radioactive contamination and all Miami cave crayfish would be exposed to high levels of radioactive contamination.
The probable current exposure of Miami cave crayfish individuals to tritium contamination and the potential future exposure of the species to widespread radioactive contamination from tritium and other radioactive isotopes associated with nuclear power generation (e.g., those listed in the Radiation Source column of Table 3.4) is important because crustaceans that experience both short-term and long-term exposure to radiation can exhibit high rates of mortality and morbidity.
Adverse effects in crustaceans vary based on dosage, type, and duration of exposure and, in some cases, are multigenerational (Fuller et al. 2015, pp. 57, 58, 60-63).
Although there are no current studies of the adverse effects of radiation on Miami cave crayfish, we predict the species to have similar adverse reactions to radiation exposure (e.g., mortality at lethal dosages and physiological, reproductive, developmental, growth, and behavioral defects at sublethal levels; Fuller et al. 2015, pp. 57-58, 60-63) (Table 3.4). The influence of radioactive contamination on Miami cave crayfish individuals is predicted to be significant enough to generate population and analysis unit level negative effects in the case of low to moderate exposure. In the case of widespread high to extremely high radioactive contamination, we anticipate the adverse effects to translate to the entire species with possible extinction occurring in the event of a nuclear meltdown.
Exhibit 16
64 Table 3.4. Summary of effects of chronic and acute radiation exposure on crustacean morbidity.
Acute exposures are defined as those lasting less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Chronic exposures are defined as those lasting over a period of the organisms life span and greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. HTO = Tritiated Water. From Fuller et al. (2015, p. 60). Refer to Fuller et al. (2015) for original references cited in table below.
3.4.4 Groundwater Protection Regulations Biscayne Aquifer groundwater has limited protective benefits from anthropogenic contamination under federal, state, and county regulations. Most regulatory protections focus on surface water quality, which offers indirect benefits to the quality of freshwater within the Biscayne Aquifer system. The primary laws and ordinances pertaining to water quality protection that directly or indirectly affects groundwater quality in the endemic range of Miami cave crayfish include (but are not limited to):
Exhibit 16
65 Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (the Superfund law) (42 U.S.C. § 9601 et seq.): identifies, evaluates, and cleans up sites contaminated with hazardous substances.
Resource Conservation and Recovery Act (42 U.S.C. ch. 82 § 6901 et seq.): establishes standards for the treatment, storage, and disposal of hazardous waste from municipal and industrial sources, including that contained in underground storage tanks.
Safe Drinking Water Act (42 U.S.C. § 300f): establishes National Primary Drinking Water Regulations for contaminants that may cause adverse public health effects, including mandatory requirements related to maximum contaminant levels and treatments.
Clean Water Act of 1972 (33 U.S.C. §1251 et seq.): indirectly benefits groundwater quality by protecting the quality of surficial waters.
The Everglades Forever Act (Section 373.4592(4)(f), F.S.): establishes best management practices in the Everglades Agricultural Area, which is underlaid by the Biscayne Aquifer and so indirectly benefits from these regulations The Grizzle-Figg Statute (Section 403.086, F.S.): outlines requirements for safe sewage disposal facilities and treatment of discharges from these sewage facilities Identification of Impaired Surface Waters (Section 62-303, F.S.): establishes water quality standards and protocols by which Florida assesses, lists, and delists impaired surface waters, which indirectly protects adjacent aquifer systems Miami-Dade County Ordinance for Florida-Friendly Fertilizer Use for Urban Landscapes: regulates fertilizer application and use in the incorporated and unincorporated areas of the county Miami-Dade County Wellfield Protection Regulations: prohibits or limits activities that use or store hazardous materials, generate hazardous waste, excavate to any depth, or require the installation of septic tanks within a wellfield protection area (refer to Figure 3.1.8, Appendix D to view distribution of wellfields across the endemic range of Miami cave crayfish).
3.4.5 Summary of Groundwater Contamination by Anthropogenic Sources The high permeability of the Biscayne Aquifer makes it susceptible to contamination from surficial inputs, belowground septic tanks, and bordering water bodies. Pharmaceuticals, pesticides, volatile organic compounds, excess nutrients, and excess trace elements are introduced into groundwater throughout Miami-Dade County by a variety of land uses associated with development, agriculture, and recreation. These contaminants are concentrated in canals and other water bodies from which they seep into the Biscayne Aquifer. The close proximity of Turkey Point Nuclear Power Point to the Atlantic Coastal Ridge introduces the potential for radioactive contamination of Miami cave crayfish habitat. Few regulations exist to specifically protect groundwater quality in the Biscayne Aquifer. Using other crayfish and crustaceans as analogues, we predict that Miami cave crayfish experience increased morbidity, mortality, and Exhibit 16
66 reproductive loss when exposed to anthropogenic contaminants. For this reason, we identify groundwater contamination as one of the most significant threats to the species across its endemic range.
3.5 Saltwater Intrusion Saltwater intrusion occurs when saltwater enters via multiple pathways into a fresh water (i.e.,
water with a chloride concentration of 0.45 parts per thousand (ppt)) aquifer system (Prinos et al. 2014, p. 2). The saltwater interface refers to the diffuse zone of mixing between the fresh water of the aquifer system and the intruded saltwater, a non-distinct area where chloride concentrations range between those delineating fresh water and saltwater (Prinos et al. 2014, p.
2).
Four main processes contribute to the intrusion of saltwater into aquifer systems like the Biscayne Aquifer: 1. the squeezing out or escape of saltwater that had been previously stored in sedimentary rocks, 2. the gradual advance of oceanwater along the base of the aquifer as a result of lowering freshwater levels within the aquifer (section 3.3), 3. seepage of hypersaline water from coastal saltwater marshes, and 4. leakage of saltwater from canal systems that feed into the ocean (Prinos et al. 2014, pp. 12-16) (Figure 3.5.1). The Biscayne Aquifer within the endemic range of Miami cave crayfish is especially susceptible to saltwater incursion due to the regions overall low altitude and topographic gradient, its highly permeable nature, and the bordering saltwater sources of the Atlantic Ocean, Biscayne Bay, and Florida Bay (Prinos et al 2014, p. 2).
As a result, by 2018, the saltwater interface had already reached an inland extent along the Atlantic Coastal Ridge that overlapped the range of analysis units 1, 2, 3, 5, 6, and 7 (Prinos et al. 2019, entire) (Figure 3.5.2). Since the saltwater interface is a gradient rather than a distinct line between saltwater and freshwater and varies in its extent, concentration, and depth over time and distance (Figure 3.5.1), we are unable to estimate the exact amount of Miami cave crayfish habitat lost to saltwater intrusion.
Exhibit 16
67 Figure 3.5.1. Conceptual diagram of sources and mechanisms of saltwater intrusion into a freshwater aquifer. Changes in water chemistry that may result from this intrusion are also illustrated. From Prinos et al. (2014, p. 16).
Exhibit 16
68 Figure 3.5.2. Representation of the estimated extent of the saltwater incursion (red line) into the Biscayne Aquifer in Miami-Dade County as of 2018. Boundaries of analysis units depicted by black lines for reference. Map drafted in GIS with data provided by Prinos et al. (2019).
Exhibit 16
69 3.5.1 Impact on Miami Cave Crayfish Although most surface-dwelling crayfish are able to persist in saline environments in the short-term (i.e., a few days to a few months), exposure to salinity levels above those of their natural habitats causes inhibition of growth, limited to no reproduction, reduced numbers and death of fertile eggs, lower hatching success, and elevated mortality (Veselý et al. 2017, pp. 4-5). The salinity tolerance of Miami cave crayfish has yet to be assessed. Using surface crayfish taxa as analogues, we determine it to be highly unlikely that Miami cave crayfish could sustain reproductively successful populations at salinity measures above those evidenced in the natural freshwater aquifer environments from which they have been collected (i.e., 0.45 ppt). The closely-related, surface-dwelling Everglades crayfish lives in brackish water environments with salinity values up to 18 ppt (Hendrix and Loftus 2000, p. 194). Even when employing this value as an upper range of salinity tolerance for Miami cave crayfish, the species is still not predicted to be able to persist in the saline habitats accompanying saltwater incursion into the Biscayne Aquifer.
3.5.2 Mitigating Factors The two primary processes driving saltwater incursion into the Biscayne Aquifer along the Atlantic Coastal Ridge are seepage from canal systems and encroachment of saltwater from the ocean (Prinos et al. 2014, pp. 2, 41-42, 48-55, 66). Accordingly, movement of the saltwater interface within the aquifer system is moderated by: 1. water management projects, 2. climatic conditions, 3. groundwater-flow direction, 4. the distribution of porosity within karstic limestone, and 5. freshwater levels in the aquifer relative to sea level (Prinos et al. 2014, p. 6).
3.5.2.1 Water Management, Groundwater Flow, and Aquifer Drawdown Modern water management and its impact on saltwater intrusion has had a long history in the Miami area, beginning with the coordinated draining of the Everglades wetland ecosystem in 1845. Historically, canals along the Atlantic Coastal Ridge aided in draining the adjacent wetland systems, which led to a permanent drop of about 9.5 ft (2.9 m) in regional groundwater levels within the Biscayne Aquifer (Prinos et al. 2014, pp. 2, 64). As a result, saltwater incursion began to expand inward from the coast (Prinos et al. 2014, p. 64). Concurrently, saltwater flowed up the expanded canal systems from the ocean and seeped into the surrounding aquifer system (Prinos et al. 2014, p. 64). As reviewed in section 3.3, groundwater withdrawals to meet the demand of a growing populace and the agricultural and industrial sectors decreased the freshwater levels within the Biscayne Aquifer, which furthered the inland creeping of the saltwater interface along the base of the aquifer from the coast.
Exhibit 16
70 Todays water management system is operated by the South Florida Water Management District and includes a complex, interconnected network of water conservation areas, well-fields, water control structures, levees, pumps, and canals. Despite the installation of salinity control structures along most of the tidal canal system in Miami-Dade County, these devices have proven highly ineffective at controlling saltwater leakage around control structures and saltwater seepage from canals into the adjacent aquifer system is still one of the primary mechanisms by which saltwater intrusion occurs in the region (Prinos et al. 2014, pp. 42, 43, 47-55, 66).
An additional project recently initiated by South Florida Water Management District that is likely to significantly impact saltwater incursion is the construction of a 19-to 31-mile curtain wall west of the Atlantic Coastal Ridge, which will ostensibly manage waters within the Everglades wetland ecosystem and protect the coastal urbanized areas of Miami-Dade County from flooding (Owosina 2020, unpaginated) (Figure 3.5.3). The curtain wall will be cut to the base of the Biscayne Aquifer in order to control groundwater flow along its entire length (Owosina 2020, unpaginated) (Figure 3.5.4).
Once completed, the curtain wall will alter the water flow dynamics of the Biscayne Aquifer, particularly to the east of the structure on the Atlantic Coastal Ridge where westward flow from the Everglades wetland ecosystem in the east will be greatly reduced. Currently, a general eastward and southeastward direction of groundwater flow along the Atlantic Coastal Ridge counters the encroachment of saltwater from the ocean (Prinos et al. 2014, p. 6). Any loss or weakening of this flow directionality will directly impact the landward migration of the saltwater interface within the endemic range of Miami cave crayfish. In addition, any loss of freshwater recharge provided by the Everglades wetland ecosystem will most likely drop the groundwater levels of the Biscayne Aquifer on the Atlantic Coastal Ridge, further contributing to saltwater incursion as well as reducing the quantity of aquifer habitat available to the species.
Exhibit 16
71 Figure 3.5.3. Illustration of three potential curtain wall locations, east of Everglades National Park and west of the Atlantic Coastal Ridge. Image by South Florida Water Management District from Owosina (2020, unpaginated).
Exhibit 16
72 Figure 3.5.4. Illustration of aquifer flow before and after installation of a curtain wall. Yellow line indicates groundwater level. Blue arrows demonstrate amount and direction of groundwater flow. Red line (bottom scene) represents curtain wall. Cartoon by South Florida Water Management District from Owosina (2020, unpaginated).
3.5.2.2 Climate Change Climatic factors tied to south Floridas wet and dry seasons, flooding events, and droughts greatly influence the location of the saltwater interface within the Biscayne Aquifer (Prinos et al.
2014, p. 6). Extended dry seasons, periods of drought, and elevated temperatures all contribute to the loss of freshwater from the aquifer system due groundwater drawdown and impeded recharge of aquifer reserves (section 3.3), resulting in the increased flow of ocean water along the base of the Biscayne Aquifer (Prinos et al. pp. 55, 64, 65). Canal levels are also lower during these times, which permits the flow of saltwater from the ocean up the canal systems inland. The saltwater then diffuses into the Biscayne Aquifer along the canal banks (Bradner et al. 2005, p. 5; Exhibit 16
73 Prinos et al. 2014, pp. 64, 65). Illustrating this process is the drastic saltwater intrusion along the Atlantic Coastal Ridge that accompanied the severe drought of 1943-1946. As canal water levels fell, saltwater migrated up all of the primary canals at least 3.7 miles (6 km) from the ocean (Prinos et al. pp. 18, 20). By 1945, saltwater had traveled inland between 6.8 to 12.4 miles (11 to 20 km) in eight of these canals (Prinos et al. pp. 18, 20).
Exacerbating this inland flow of saltwater through the canal system are rising regional sea levels, elevated tidal flooding (e.g., king tides), and tropical storm-driven storm surges (Prinos et al.
2014, pp. 13, 16). Conversely, during periods of flood, high precipitation events, and the wet season, water levels within the aquifer system and the canals begin to rise, pushing the saltwater intrusion back towards the coastline (Bradner et al. 2005, p. 5; Prinos et al. 2014, p. 65).
In the future, regional sea levels are projected to rise by as much as 8.2 ft (2.5 m) over the next 50 years (Table 3.5). As reviewed in section 3.1.4, temperatures are predicted to rise as well (Figure 3.16), while dry seasons, droughts, and tropical storms are likely to become more extreme (IPCC 2014, pp. 1452-1456; Infanti et al. 2020, entire; IPCC 2021, pp. 32, 33) (Figure 3.17; Appendix C). The cumulation of all of these climatic factors is highly likely to result in the continued inland migration of the saltwater interface in the Biscayne Aquifer along the Atlantic Coastal Ridge. A concurrent rise in the frequency, intensity, and duration of precipitation events may also occur (Infanti et al. 2020, entire) and slow some of the inland movement of the saltwater incursion, but these mitigating effects are not anticipated to be significant in the long-term. Consequently, Miami cave crayfish populations, especially those more proximate to the coast and/or canal systems, will be extirpated with the encroachment of saltwater into their aquifer habitats. The loss of these habitats along the eastern edge of the Atlantic Coastal Ridge is particularly impactful since these coastal areas exhibit the greatest aquifer depths and, thus, the greatest overall quantity of Miami cave crayfish habitat.
Exhibit 16
74 Table 3.5. Regional sea level rise with 1% annual chance flood heights and confidence intervals (CI) projected to 2070 based on analysis for Virginia Key, Florida. The regional sea level rise and extreme sea levels are relative to the geodetic datum NAVD88, which is 0.27 cm above local mean sea level for the 1983-2001 epoch. From Sweet et al. (2017, p. 41).
3.5.3 Summary of Saltwater Intrusion The main sources of saltwater intrusion into the Biscayne Aquifer are via leakage from canals and encroachment along the base of the aquifer from the ocean. Factors such as water management, climatic conditions, regional sea level rise, aquifer drawdown, and groundwater flow all influence the movement of the saltwater interface within the Biscayne Aquifer. As of 2018, saltwater intrusion was affecting six of the seven Miami cave crayfish analysis units. Since the species is predicted to be intolerant to saltwater conditions, any portions of the aquifer intruded by saltwater can no longer sustain populations of Miami cave crayfish and, therefore, saltwater intrusion poses a threat to the species. Most significantly, the largest volume of Miami cave crayfish habitat is located along the eastern region of the Atlantic Coastal Ridge, which is where the highest degree of saltwater intrusion has occurred.
3.6 Other Possible Influences Little to nothing is known about the effects of competition, predation, disease, and overutilization on Miami cave crayfish, and we have not determined any of these stressors to be of significant risk to the species. Accordingly, we briefly address the possible effects of these threats to Miami cave crayfish, but do not carry these influences forward into our current or future conditions analyses.
Exhibit 16
75 3.6.1 Competition and Predation There is a paucity of information regarding the sympatric species with which Miami cave crayfish share their karstic limestone aquifer habitat on the Atlantic Coastal Ridge (Loftus and Trexler 2004, entire). A possible predator and/or competitor (i.e., for small crustacean and other invertebrate prey) is an unidentified blind cave fish, which has been observed by multiple members of the public from well blowouts and during canal construction (Loftus and Trexler 2004, p. 44; Loftus pers. comm. 2021). Based on biogeography and physical descriptions provided by witnesses, this stygobitic blind fish is likely a member of the family Bythitidae (viviparous brotulas), which could potentially serve as predators of both juvenile and adult Miami cave crayfish.
Other potential competitors and/or predators of Miami cave crayfish include native and alien invasive fish species that forage in aquatic environments that contact the open cavity systems of the karstic limestone in which Miami cave crayfish live. Canals dissect the habitat of Miami cave crayfish, which bring crayfish and their prey into contact with native and non-native predatory fishes (Loftus, pers. comm. 2021). Anthropogenic activities not only create entry points for alien invasive species invasion and establishment (e.g., well-drilling and groundwater exposure through other construction), but may also supply the exotic species themselves.
For example, predatory cichlids have been introduced into groundwater by the flow through systems used by the aquaculture operations that breed them (Loftus and Trexler 2004, pp. 42, 44; Loftus pers. comm. 2021). Analogous unintentional stocking of wells with escapee aquaculture-bred fish is likely common throughout the region. In this scenario, any Miami cave crayfish entering the well water are easy meals for the food-limited cichlids and other predatory fish inhabiting these wells.
A similar scenario plays out anywhere open aquatic environments contact the open cavity system of the Biscayne Aquifer (e.g., lakes, canals). In these systems, over a dozen native and alien invasive fish species could competitively or predatorily interact with Miami cave crayfish (Walsh 2001, p. 81; Loftus and Trexler 2004, p. 42; Kline et al. 2014, entire; Loftus pers. comm.
2021). The direct threat of predaceous fish is most likely localized in nature since physical constraints (e.g., the size of interconnected cavities in the limestone) and water quality restrictions (e.g., surface fish usually cannot tolerate the low levels of dissolved oxygen typifying groundwater habitats) prevent these species from dispersing too far into the subterranean aquifer system (Loftus pers. comm. 2021). However, the impact of incidental predation over time may be significant on Miami cave crayfish populations adjacent to these areas, attracted to the higher concentrations of nutrients and dissolved oxygen in these transitional environments.
3.6.2 Disease Exhibit 16
76 Infectious diseases can contribute to the decline and extinction of wildlife species in cases where spillover or emerging novel pathogens affect naive populations and/or endemic disease dynamics are altered by environmental or demographic shifts (Daszak et al. 2000). To date, no parasites or viral, bacterial, or fungal diseases have been identified in Miami cave crayfish. However, a captive population of the species in an aquacultural facility experienced a substantial die-off from an infectious disease of unknown origin (Loftus and Trexler 2004, p. 46). All wild-caught individuals collected between 2000 and 2004 had no distinguishable signs of parasites, disease, or injury (Loftus pers. comm. 2021).
Miami cave crayfish proximate to areas of septic tanks, sewer overflows, animal agriculture, aquaculture, and other potential sources of pathogen contamination (e.g., below the impaired surface waters listed by the Florida Department of Environmental Protection due to elevated levels of fecal coliform bacteria; Figure 3.4.2) are at higher risk of infectious disease spillover into their populations. Aquacultural operations pose an elevated risk of disease spillover due to their routine use of flow-through water systems, which pump groundwater directly from the aquifer, through animal holding tanks, then directly back, untreated into the aquifer (Loftus pers.
comm. 2021). Aquaculture facilities more often than not host a wide variety of parasites and infectious pathogens, which can be subsequently circulated into and dispersed throughout the surrounding aquifer system, potentially exposing any Miami cave crayfish in the region (Shapiro et al. 2008, entire; Paladini et al. 2017, entire). Miami cave crayfish are at the highest risk of disease from breeding facilities that raise crayfish and other crustaceans since Miami cave crayfish are more likely to be susceptible to the pathogens transmitted by these closely-related species.
3.6.3 Overutilization There is a potential threat of overutilization to imperiled species. In particular, the threat to crayfish species from overutilization is from the collection of individuals for bait or food. Due to its existence in difficult to access aquatic cave habitats, it is not surprising that there is no information that this species is being utilized for food or bait. The species and its habitats are also not known to be targeted for significant scientific or educational collections. Florida State Code 68A-9.002 authorizes the Director of the Florida Fish and Wildlife Conservation Commission to issue permits to collect any wildlife species for scientific or conservation purposes, which are required for activities that are otherwise prohibited. Based on the difficulty in sampling the species and accessing private lands to do so, scientific collection has been minimal. In addition, Florida Statute Chapter 810.13 makes it unlawful to remove, kill, harm, or otherwise disturb any naturally occurring organism within a cave (including springs and sinkholes), except for safety or health reasons. Although this species is sought after by aquarists in Europe and Russia (Faulkes et al. 2015, p. 77), the trade is sustained entirely by captive-bred individuals, which can be traced back to the initial captive stock described by Radice and Loftus (1995) and Loftus and Trexler (2004). Consequently, wild Miami cave crayfish are not threatened with overutilization.
Exhibit 16
77 3.6.4 Summary of Other Possible Influences Miami cave crayfish may experience localized predation by and/or competition with native and non-native fish. A captive population of the species experienced a die-off from an unidentified infectious pathogen, but no parasites or diseases have been reported from wild individuals.
Miami cave crayfish are at an elevated risk of disease spillover events in areas with human and animal wastewater influx, especially contaminated water disposed directly into groundwater by aquacultural flow-through systems. There is very limited collection of Miami cave crayfish for scientific purposes and none related to the foreign pet trade (sustained by captive breeding) or consumptive activities. Based on the best available information, we determine predation, competition, disease, and overexploitation pose no significant threat to the species at this time.
3.7 Summary of Influences on Viability Miami cave crayfish and their habitats face a multitude of natural and anthropogenic influences, which can adversely or positively affect the species needs. These influences originate from a variety of sources (e.g., development/urbanization, agricultural practices, climate change, water management, conservation activities), and often multiple sources contribute to a single influence, while a single source acts upon the species through multiple influences. The primary effects impacting Miami cave crayfish populations include alterations to water quality, freshwater quantity, surface cover, and subterranean habitat. As a result of the highly restricted endemic range of Miami cave crayfish, the species is especially vulnerable to the negative impact of modification of the quality and quantity of freshwater in the Biscayne Aquifer system, loss of karstic limestone from the Atlantic Coastal Ridge, and degradation of natural surface cover overlying its subterranean habitats (Loftus and Trexler 2004, p. 50). Since disease, predation, competition, and overexploitation were not determined to be significant influences on the species, we did not carry these factors forward in this assessment. Instead, we focus on the significant influences of modification of surface cover, modification of karstic limestone, freshwater drawdown within the Biscayne Aquifer, anthropogenic contamination of groundwater, and saltwater intrusion in our current and future conditions analyses for Miami cave crayfish (Figure 3.7).
Exhibit 16
78 Figure 3.7. Presumed influence diagram for the Miami cave crayfish depicting the influences that we carry forward into the current conditions analysis (Chapter 4) and future conditions analysis (Chapter 5). This figure is a simplistic representation of the presumed influence relationships, and many feedback loops and interrelationships exist within and between levels that are not depicted here. Refer to Appendix A for a more detailed description of these linkages.
CHAPTER 4 - ANALYSIS OF CURRENT CONDITION Historically, all Miami cave crayfish were likely part of a single metapopulation with some degree of connectivity (Section 2.6). There is no information available regarding the demographic, ecological, morphological, and/or genetic processes that define the spatial structure of Miami cave crayfish populations. However, primary canals transecting the Atlantic Coastal Ridge habitat of the species serve to effectively isolate populations of Miami cave crayfish into seven distinct analysis units of the species (Figure 2.6.2). During the most recent surveys in 2018, Miami cave crayfish were present in two of the seven analysis unit regions (section 2.6). In a broader survey effort between 2000-2004, the species was present in four of the seven analysis units, including the two analysis units from the 2018 surveys. Analysis unit 6 has a reported occurrence of several individuals in 2009, while the occupancy of analysis unit 1 is based on anecdotal evidence (Loftus pers. comm. 2021; P. Moler pers. comm. 2021). There is no confirmed presence of Miami cave crayfish in analysis unit 5.
Given that the species is difficult to detect, survey locations are limited due to restricted access (e.g., on private property), and extensive range-wide sampling has never been conducted, we cannot discount the possibility that Miami cave crayfish persist in areas from which they have not been sampled. For this reason, we assume that Miami cave crayfish are present in all seven Exhibit 16
79 analysis units, which we use for the purpose of evaluating the current condition of Miami cave crayfish.
4.1 Current Species Resiliency A number of factors influence whether Miami cave crayfish populations will grow to maximize habitat occupancy, which increases the overall viability of the species. These factors correspond to the individual, population, and species needs of Miami cave crayfish and are as follows: 1.
freshwater availability (water quantity), 2. sufficient water quality, 3. food availability, and 4.
karstic limestone substrate with interconnected megaporosities.
We analyzed the resiliency of Miami cave crayfish using four metrics to evaluate these species needs. We have consistent, quantitative data to assess the quantity of karstic limestone aquifer habitat to which Miami cave crayfish populations have access and the type of surface cover overlying the species endemic range, influencing food availability of the species. Although freshwater quality and quantity has not been consistently evaluated across the Biscayne Aquifer throughout the Atlantic Coastal Ridge, we were able to indirectly assess probable sources of anthropogenic freshwater contamination via an analysis of land use overlapping Miami cave crayfish habitat. In addition, we used estimates of saltwater intrusion into the Biscayne Aquifer system to calculate relative measures of freshwater loss to elevated salinity. Each section below summarizes the quantitative parameters we used to assess Miami cave crayfishs current condition, with additional details provided in Appendix E.
4.1.1 Habitat Quantity - Quantity of Karstic Limestone Aquifer Habitat Habitat elements that are important to Miami cave crayfish include a freshwater aquifer system within a limestone substrate containing abundant interconnected networks of cavities. Therefore, Miami cave crayfish require adequate freshwater availability. The Biscayne Aquifer inhabited by Miami cave crayfish is sustained primarily by direct recharge in the Everglades wetland ecosystem and by precipitation. The quantity of freshwater within the aquifer is controlled not only by fluctuations in these recharge processes, but also flow pattern variations related to water control structures, canals, large well fields, and pumping for agricultural, residential, and commercial use (Fish and Stewart 1991, pp. 8, 23-24, 40-44; Wacker et al. 2014, p. 1; Whitman and Yeboah-Forson 2015, p. 781). If groundwater levels in the Biscayne Aquifer are curtailed or eliminated on the Atlantic Coastal Ridge, Miami cave crayfish populations could lose resiliency or become extirpated.
Miami cave crayfish are just as dependent on the interconnected networks of megaporosities within the Atlantic Coastal Ridges Miami Limestone and Fort Thompson Formation to provide conduits for freshwater flow, which maintains high water quality and quantity and enhances carbon flow into and within their aquifer habitat. The karstic systems of interconnected cavities Exhibit 16
80 are also used by Miami cave crayfish for movement, which supports connectivity of individuals and subpopulations. Any compromise or destruction of the Atlantic Coastal Ridges karstic limestone within the aquifer system is likely to have a direct adverse impact on the species and could cause Miami cave crayfish populations to lose resiliency or to be extirpated.
In order to evaluate the presence and quantity of these habitat elements (i.e., karstic limestone occupied by the Biscayne Aquifer) throughout the species endemic range, we used the most recent available data for the depth of the Biscayne Aquifer on the Atlantic Coastal Ridge collected by Hughes and White (2016, p. 26) and land use and sewer line infrastructure data provided by Miami-Dade County (2018, 2021a). We then compared the quantity of karstic limestone aquifer habitat currently present in the range of each analysis unit of Miami cave crayfish to the habitat that would be present in the absence of any anthropogenic influence (Table 4.1). See Appendix E for more detailed information.
Table 4.1. Habitat Quantity factors for each analysis unit of Miami cave crayfish. Percentage of habitat represents the amount of current habitat available compared to habitat that would be available in the absence of anthropogenic effects.
Analysis Unit Percentage of Habitat Resiliency 1
98 High 2
98 High 3
98 High 4
97 High 5
93 High 6
99 High 7
98 High We used these percentages to estimate each analysis units population resiliency measure for this habitat quantity factor according to the relationship detailed in Table 4.2. For all analysis units of Miami cave crayfish, Habitat Quantity is in a high condition. We attribute these high values to the relatively minor loss of karstic limestone from infrastructure and quarrying activities on the Atlantic Coastal Ridge and the water level drop in the Biscayne Aquifer of only 9.5 ft (2.9 m) since the early 19th century (Prinos et al. 2014, p. 17). However, this factor only assesses the quantity of habitat present and does not evaluate the quality of that habitat. If physical habitat features are present, but other important components of the habitat are absent (e.g., adequate water quality), organisms may not be able to persist in the habitat and the species may not be able to sustain viable populations in the area.
Table 4.2. Relationship between Habitat Quantity and Habitat Quality values and population resiliency measures.
Exhibit 16
81 Population Resiliency Factor High Moderate Low Quantity of karstic limestone aquifer habitat (Habitat Quantity) 80%
50-80%
50%
Quality of surface cover (Habitat Quality) 80%
50-80%
50%
Freshwater Quality (Anthropogenic Contamination Measure) (Habitat Quality) 80%
50-80%
50%
Freshwater Availability (Saltwater Intrusion Measure) (Habitat Quality) 20%
20-50%
50%
4.1.2 Habitat Quality - Quality of Surface Cover Miami cave crayfish subsist on surficial detritus that filters downwards into their habitat and on sympatric invertebrate prey dependent on the influx of organic carbon into their subterranean ecosystem (Section 2.4). The amount of organic carbon available to Miami cave crayfish and their prey is dependent on two factors: 1. surface deposition of this carbon, mainly from vegetation, and 2. the transportation of this carbon from the surface into subterranean habitats.
Appropriate surface cover for Miami cave crayfish will facilitate these processes by including both vegetative sources for organic carbon and sandy or no (i.e., bare Miami Limestone) soil cover to permit the movement of dissolved and coarse particulate organic matter into the aquifer ecosystems below (Section 2.5.2).
We considered surface cover to be appropriate if vegetation providing detritus directly to the system is present, land management practices maintain vegetation, and soil cover is either sand or absent such that there is direct exposure of the Miami Limestone; moderately appropriate if there is limited vegetation, land management practices maintain minimal vegetation, and/or soil cover restricts carbon flow (e.g., sand mixed with silt or clay); and not appropriate if vegetation is not present, land management practices do not maintain vegetation, and/or surface cover obstructs carbon flow (e.g., impermeable pavement).
We assessed the quality of surface cover throughout the range of each analysis unit of Miami cave crayfish using a global land use/land cover map for the year 2020 provided by Esri (2021)
(Figure 4.1.1). Based on the ten classes of land use/land cover in this land cover map, we sorted the quality of surface cover into three categories: high, moderate, and low (Table 4.3; Figure 4.1.2). Next, we calculated the total surface area covered by each of these categories and adjusted the values of the total surface area via multipliers related to surface cover quality (0.1 for low quality, 0.5 for moderate quality, and 1 for high quality). Finally, we used these modified values of total surface area to compare the quality of surface cover currently present in the range Exhibit 16
82 of each analysis unit of Miami cave crayfish to that which would be present in the absence of any anthropogenic influence (Table 4.4). See Appendix E for more detailed information.
Table 4.3. Categorization of 2020 global land use/land cover map classifications (Esri 2021) into quality of surface cover measures for Miami cave crayfish. Water was not categorized since this feature was removed from analysis. N/A: Not applicable, a classification that was not used within the area of analysis.
Esri land use/land cover map classification Surface cover quality Water Removed Trees High Grass High Flooded Vegetation High Crops Moderate Scrub/Shrub High Built Area Low Bare Ground Moderate Snow/Ice N/A Clouds N/A Exhibit 16
83 Figure 4.1.1. 2020 Land Use/Land Cover map for Miami-Dade County. Atlantic Coastal Ridge is outlined in solid black line for reference. Map drafted in GIS with data provided by ESRI (2021).
Exhibit 16
84 Figure 4.1.2. Quality of surface cover in endemic range of Miami cave crayfish. Analysis units are outlined in solid black line for reference. White areas represent water or areas of no data per ESRI (2021). Map drafted in GIS with data provided by ESRI (2021).
Exhibit 16
85 Table 4.4. Habitat Quality factors for Quality of Surface Cover for each analysis unit of Miami cave crayfish.
Analysis Unit Percentage of Habitat Resiliency 1
36 Low 2
29 Low 3
32 Low 4
18 Low 5
19 Low 6
13 Low 7
11 Low We used these percentages to estimate each analysis units population resiliency measure for this habitat quality factor according to the relationship detailed in Table 4.2. For all analysis units of Miami cave crayfish, the surface cover quality factors were low. Since the majority of land cover/land use in the endemic range of Miami cave crayfish is classified as built area (Figure 4.1.1), most of the surface cover above all Miami cave crayfish analysis units is of low quality (Figure 4.1.2) and, therefore, confers low resilience to each analysis unit.
4.1.3 Habitat Quality - Freshwater Quality Freshwater quality must be sufficient to sustain Miami cave crayfish populations. We consider water quality to be functioning at a high level if water conditions provide appropriate conditions for Miami cave crayfish occupation and reproduction; at a moderate level if water conditions provide marginal conditions for Miami cave crayfish occupation and reproduction; and at a low level if water conditions are unable to support Miami cave crayfish occupation and reproduction.
Since there is limited information regarding the water quality parameters necessary to sustain reproductively-successful Miami cave crayfish individuals and populations over time, it is difficult to determine what specific ranges of each water quality measure are appropriate for the species (Section 2.5.3). Therefore, we define sufficient water quality as not exhibiting: 1.
excessively high temperature, acidity (pH), dissolved solids (specific conductance),
anthropogenic contaminants (i.e., pharmaceuticals, pesticides, volatile organic compounds, excess nutrients, and excess trace elements), or 2. excessively low temperature, acidity (pH), or dissolved oxygen. Range-wide data pertaining to measures of these values are currently unavailable. However, we can approximate the degree of influence of non-natural sources of water contamination on Miami cave crayfish by assessing land use in Miami-Dade County and particle transport behavior within the Biscayne aquifer system.
Exhibit 16
86 In section 3.4, we reviewed the likely effects of the five main categories (i.e., pharmaceuticals, pesticides, volatile organic compounds, excess nutrients, and excess trace elements) of anthropogenic water contamination on Miami cave crayfish as well as the main sources of these pollutants. Based on this information, we categorized each of the land use types represented in the Miami-Dade County Regulatory and Economic Resources Departments Planning Division (2021a) data as a source or non-source for each class of non-natural water contaminant. In addition, we analyzed septic tank locations within the range of Miami cave crayfish provided by Miami-Dade County (2021b) as contributors of both pharmaceuticals and excess nutrients (refer to section 3.4). Total source values were calculated for each land use type and septic tank location and then classed into high, moderate, and low freshwater quality categories.
We used estimates for particle transportation distances through the Biscayne Aquifer below the Atlantic Coastal Ridge (Harvey et al. 2008, entire; Shapiro et al. 2008, entire) to calculate buffers around each septic tank and land use type to simulate the spread of anthropogenic pollutants from point sources through the freshwater below (Figure 4.1.3). Next, we calculated the total surface area covered by each of these buffered freshwater quality categories and adjusted the total surface area measures via multipliers related to their freshwater quality values (0.1 for low, 0.5 for moderate quality, and 1 for high quality). Finally, we used these modified values of total surface area to compare the quality of freshwater currently present in the range of each analysis unit of Miami cave crayfish to that which would be present in the absence of any anthropogenic influence (Table 4.5). See Appendix E for more detailed information.
Table 4.5. Habitat Quality factors for Freshwater Quality related to anthropogenic water contamination for each analysis unit of Miami cave crayfish.
Analysis Unit Percentage of Habitat Resiliency 1
10 Low 2
11 Low 3
10 Low 4
11 Low 5
10 Low 6
10 Low 7
10 Low Exhibit 16
87 Figure 4.1.3. Water quality related to anthropogenic water contamination in endemic range of Miami cave crayfish. Analysis units are outlined in solid black line for reference. Map drafted in GIS per description in text.
We used these percentages to estimate each analysis units population resiliency measure for this habitat quality factor according to the relationship detailed in Table 4.2. For all analysis units of Miami cave crayfish, the anthropogenic water contamination-related freshwater quality factors were low. Since almost all of the land uses within the endemic range of Miami cave crayfish Exhibit 16
88 serve as significant sources of groundwater contamination, the seven analysis units of the species inhabit aquifer environments with relatively low water quality.
4.1.4 Habitat Quality - Freshwater Availability Freshwater quality and availability within the endemic range of Miami cave crayfish is further impacted by the intrusion of saltwater into the Biscayne Aquifer (section 3.5). Currently, there are no data that would enable us to reliably estimate the degree of saltwater contamination of the species habitat either in terms of the total depth or volume of aquifer system affected or the variation in concentration of ionic solutes across the saltwater intrusion. Therefore, we use a relative measure to evaluate the influence of saltwater intrusion on Miami cave crayfish habitat occupancy.
The approximate inland extent in 2018 of the saltwater interface in the Biscayne Aquifer in Miami-Dade County has been estimated (Prinos 2019, entire) (Figure 3.5.2). For each Miami cave crayfish analysis unit, we quantified the total surface area of available habitat that overlapped the mapped region of saltwater intrusion as of 2018. Natural fluctuations of saltwater intrusion into the Biscayne Aquifer occur in the absence of groundwater pumpage, climate change-induced sea level rise, and water management (Prinos et al. 2014, pp. 1, 6, 12-13, 17), so it was not possible for us to compare current saltwater intrusion into Miami cave crayfish habitat with estimated values for the extent of saltwater intrusion that would exist without anthropogenic effects. Instead, we calculated the percent that the total surface area overlaying the saltwater intrusion accounted for of the total surface area of habitat for each analysis unit (Table 4.6). See appendix E for more detailed information.
Table 4.6. Habitat Quality factors for Freshwater Availability related to saltwater intrusion for each analysis unit of Miami cave crayfish.
Analysis Unit Percentage of Habitat Resiliency 1
5 High 2
17 High 3
19 High 4
0 High 5
77 Low 6
26 Moderate 7
51 Low We used these percentages to estimate each analysis units population resiliency measure for this habitat quality factor according to the relationship detailed in Table 4.2. Analysis units 5 and 7 exhibited low values for this population resiliency factor, while analysis unit 6 exhibited a moderate value and analysis units 1, 2, 3, and 4 exhibited high values. The coastal portions of Exhibit 16
89 each analysis unit were more greatly affected by saltwater intrusion than were the more inland regions. Since analysis units 5, 6, and 7 have the greatest proportion of their habitat proximate to the coast, these are also the analysis units exhibiting the greatest impact from saltwater intrusion.
Analysis unit 4 is located the farthest landward of all of the analysis units and has no coastline habitat, which currently buffers the unit from any measurable effects of saltwater intrusion (Figure 3.5.2).
4.1.5 Habitat Availability - Combining Habitat Quantity and Quality Measures In order to summarize the overall resiliency of Miami cave crayfish, we combined the measures of Quality of Surface Cover (section 4.1.2), Freshwater Quality (section 4.1.3), and Freshwater Availability (section 4.1.4) to generate a Habitat Quality factor for each analysis unit. We determined that quality of available habitat was a stronger driver of Miami cave crayfish resiliency than was quantity of available habitat. As described above, the presence of physical habitat characteristics does not ensure that the habitat will sustain viable populations since low quality of that habitat can impede its occupancy. For example, the eastern region of Miami cave crayfishs endemic range contains the greatest quantity of karstic limestone aquifer habitat, but much of it is uninhabitable for the species due to saltwater intrusion along the coast.
Consequently, we weighted the Habitat Quality factor two times higher than the Habitat Quantity factor (section 4.1.1) when combining the two values to calculate the Combined Habitat measure for each Miami cave crayfish analysis unit. See Appendix E for more detailed information. We use this Combined Habitat value as a representative measure of the resiliency of each analysis unit of Miami cave crayfish as described in Table 4.7.
Table 4.7. Relationship between Combined Habitat values and resiliency of Miami cave crayfish.
Probability of persistence over the next 50 years is based on terminology from the Intergovernmental Panel on Climate Change (2021, p. 4).
Combined Habitat Value Resiliency Score Probability of persistence over the next 50 years High High Likely to Highly Likely Moderate Moderate About as Likely as Not Low Low Unlikely to Very Unlikely For all analysis units of Miami cave crayfish, Habitat Quantity factors were high and Habitat Quality factors were low. As a result, the Combined Habitat values, representing overall habitat conditions, were low for all seven analysis units of the species (Table 4.8). Subsequently, we determined that the current resiliency of Miami cave crayfish across all seven analysis units is low (Figure 4.2).
Table 4.8. Habitat factors and current resiliency of Miami cave crayfish analysis units.
Exhibit 16
90 Analysis Unit Habitat Quantity Factor Habitat Quality Factors Resiliency Score Quality of Surface Cover Freshwater Quality (Anthropogenic Contamination Measure)
Freshwater Availability (Saltwater Intrusion Measure)
Combined Habitat Quality Factor 1
High Low Low High Low Low 2
High Low Low High Low Low 3
High Low Low High Low Low 4
High Low Low High Low Low 5
High Low Low Low Low Low 6
High Low Low Moderate Low Low 7
High Low Low Low Low Low Figure 4.2. Current resiliency of Miami cave crayfish analysis units (each range denoted by associated analysis unit number).
Exhibit 16
91 4.2 Current Species Redundancy Redundancy reduces the risk that a large area of the species range will be negatively affected by a natural or anthropogenic catastrophic event at a given point in time. To determine what the Miami cave crayfish requires to guard against catastrophic events, we first considered the catastrophic events to which the species may be subjected. For the purposes of this SSA, we define a catastrophic event as a biotic or abiotic event that causes significant impacts at the population level such that the population cannot rebound from the effects and/or the population becomes highly vulnerable to normal population fluctuations or stochastic events.
We evaluated the following as plausible catastrophic events that could potentially affect one or more analysis units of Miami cave crayfish: significant flooding events (including hurricanes and storm surges), chemical spills, or other anthropogenic or natural occurrences that cause a significant discharge of contaminated water into the Biscayne Aquifer; and nuclear reactor accidents at the Turkey Point Nuclear Power Station that would result in the exposure of Miami cave crayfish to dangerously-high levels of radiation.
We considered multiple occupied sites within each section of the Atlantic Coastal Ridge bounded by primary canals within the endemic range of the species to be important for Miami cave crayfish redundancy. However, due to the highly-restricted endemic range of Miami cave crayfish, all seven analysis units are located within just 32 miles of one another in an estimated 472,800,058,577.49 cubic feet of karstic limestone aquifer habitat (Table 4.9). In addition, the water flows within the Biscayne Aquifer are largely interconnected through the extensive network of cavities within the karstic limestone composing the Atlantic Coastal Ridge.
Consequently, any catastrophic events would likely affect all of the species throughout its endemic range.
Table 4.9. Approximate volume of karstic limestone aquifer habitat currently available to Miami cave crayfish analysis units. All water bodies and limestone quarrying-related land use have been excluded from these calculations. Refer to Section Habitat Quantity - Quantity of Karstic Limestone Aquifer Habitat in Appendix E for detailed explanation of these estimated values.
Analysis Unit Total Volume of Habitat (cubic feet) 1 58,702,934,971.00 2
92,346,707,611.14 3
52,442,488,660.98 4
82,763,408,152.29 5
18,114,301,660.67 6
41,325,185,200.17 Exhibit 16
92 7
127,105,032,321.24 All, combined 472,800,058,577.49 Not only does Miami cave crayfish have inherent low redundancy from its restricted range, but this redundancy has likely worsened in comparison to its historical condition due to the anthropogenic threats discussed in Chapter 3. Indeed, all analysis units of Miami cave crayfish across the entirety of the species endemic range demonstrate low resiliency, further decreasing the species redundancy. Therefore, we determine that the species exhibits low redundancy.
4.3 Current Species Representation Representation characterizes a species adaptive potential by assessing geographic, genetic, ecological, morphological, and behavioral variability. A limited endemic range is one of the primary factors responsible for the imperilment of many crayfish species, and previous conservation assessments have noted that crayfish that are limited to one drainage system are at greater risk of conservation declines (Taylor et al. 2007, pp. 372, 377). Miami cave crayfish populations are all restricted to the Biscayne Aquifer within a single segment of the Atlantic Coastal Ridge. This limited range makes the species highly vulnerable to anthropogenic disturbances and environmental perturbations throughout its range.
To date, intraspecific variation in genetic, morphologic, and/or ecological diversity has not been investigated in Miami cave crayfish. However, very little morphological variation has been reported between populations based on the limited sampling that has been conducted (Loftus and Trexler 2004, pp. 45-47). Therefore, based on the most current information available, we assessed the species as a single representative unit and determined Miami cave crayfish to have low representation.
We do not have specific genetic or morphological diversity information to inform where there may be differences in the species within the Atlantic Coastal Ridge. However, given the highly interconnected nature of the Atlantic Coastal Ridge karst system, it is likely that genetic material is shared between Miami cave crayfish subpopulations inhabiting the regions bounded by primary canals. Exchange of genetic material between analysis units of Miami cave crayfish that are separated by primary canals is likely an uncommon event.
Since we have no knowledge of the level of intraspecific diversity of Miami cave crayfish nor of the presence of populations in other areas of the Atlantic Coastal Ridge that have yet to be surveyed, we do not delineate distinct representative units for this species. Due to the restricted and highly-endemic range of Miami cave crayfish, we instead analyze the species as a single Exhibit 16
93 representative unit. Based on the most current information available, we determined Miami cave crayfish have low representation.
4.4 Summary of Current Condition On the basis of quantitative measures of habitat condition, the resiliency of all seven analysis units of Miami cave crayfish and, thus, the species was found to be low. The restricted endemic range of Miami cave crayfish largely contributed to our assessment of the species as exhibiting both low redundancy and low representation. In addition, the interconnected nature of the Biscayne Aquifer, particularly within the range of the species, increases the susceptibility of Miami cave crayfish to a variety of catastrophic events. The low adaptive capacity of the species is further supported by the paucity of evidence for any significant divergence in morphologic, genetic, or niche factors demonstrated by Miami cave crayfish, although future research into intraspecific variation may necessitate a re-evaluation of the species degree of representation.
CHAPTER 5 - FUTURE CONDITIONS As discussed in chapter 1, for the purpose of this assessment, we define viability as the ability of the species to sustain populations in natural karstic aquifer ecosystems within a biologically meaningful timeframe (in this case, 50 years). Using the SSA framework, we describe the species viability by characterizing the status of the species in terms of its resiliency, redundancy, and representation (the 3Rs). Using various timeframes and the current and projected levels of the 3Rs, we thereby describe the species level of viability over time.
We have considered the Miami cave crayfishs life history characteristics, identified the habitat and analysis unit characteristics needed for viability (chapter 2); reviewed the factors that may be driving the historical, current, and future conditions of the species (chapter 3); and evaluated the current condition of those needs through the lens of the 3Rs (chapter 4). In this chapter, we project the Miami cave crayfishs future conditions to inform our understanding of the species risk of extinction in the future.
We used habitat information to predict how the seven analysis units are likely to respond to the primary factors that will plausibly influence the species condition in the future. These influencing factors include sea level rise, saltwater intrusion, urbanization and development, water management, conservation practices, and the overall freshwater quality and quantity within the Biscayne Aquifer. Our analysis projects four future scenarios, which are representative examples from the entire range of plausible future scenarios. For each scenario, we qualitatively Exhibit 16
94 evaluate the effects of various influences on the 3Rs and viability of each analysis unit of Miami cave crayfish and the species as a whole.
5.1 Future Scenarios Four scenarios, including a status quo scenario, were used to characterize the uncertainty regarding plausible futures for Miami cave crayfish. The 3Rs were forecasted for each scenario using each of three possible regional sea level rise scenarios (per Sweet et al. 2017, entire and Sweet et al. 2018, entire) coupled with variable levels of urbanization predicted by Florida 2070 (Carr and Zwick 2016, entire), freshwater quality and quantity scenarios we defined for the Biscayne Aquifer, and four possible extensions of the saltwater interface within Miami-Dade County.
No projections currently exist that predict the extent of saltwater intrusion into the Biscayne Aquifer by 2070, so we estimated the inland movement of the saltwater interface from its 2018 position (Prinos et al. 2019, unpaginated) based on the projections of regional sea level rise, the degree of aquifer drawdown, and anthropogenic interventions potentially altering saltwater intrusion as delineated by each plausible future scenario. The regional sea level rise scenarios adopted from Sweet et al. (2017) and Sweet et al. (2018) (e.g., Intermediate Low, Intermediate, and Extreme scenarios) encompass the extent of sea level rise predicted by the low-end and high-end likely ranges for the representative concentration pathway (RCP) 4.5 and RCP 8.5 emissions scenarios for future global temperatures projected by the Intergovernmental Panel on Climate Change assessment report 5 (Sweet et al. 2018, p. 24). The expected future resiliency of each analysis unit was forecasted based on events that were predicted to occur under each scenario. As with current condition estimates, assessments were made at the analysis unit level and were then scaled up to the species level.
Predictions of Miami cave crayfish resiliency, redundancy, and representation were evaluated using a 50-year time horizon. This timeframe was chosen to correspond to the range of available urbanization and climate change model forecasts (Carr and Zwick 2016, entire; Sweet et al.
2017, entire; Sweet et al. 2018, entire) for which there were no equivalent intermediate time steps available. In addition, 50 years represents an appropriate biological timeframe during which responses of the species to potential changes in habitat can be reasonably assessed.
Although the lifespan and generation time for Miami cave crayfish are currently unknown (section 2.3), estimates for these measures based on those reported for other subterranean crayfish taxa (Taylor et al. 1996, p. 27; Huryn et al. 2008, pp. 1, 12-15; Longshaw and Stebbing 2016, p. 68) suggest that three generations of the species would likely be represented in a 50-year time span. A summary of the four scenarios is presented in Table 5.1 and via detailed narratives below.
Exhibit 16
95 Table 5.1. Summary of the four scenarios used to assess plausible future conditions for Miami cave crayfish in 2070.
Scenario Sea Level Rise Urbanization Water Quality Condition Water Quantity Condition Saltwater Intrusion Scenario 1
Regional sea level rise of 2.49 ft (0.76 m) with 1%
annual chance flood of 5.45 ft (1.66 m).
Urbanization continues on trend with current levels.
Current level of regulation and oversight, including protective standards, requirements, and utilization of basic technologies for effluent treatment.
Continuing trend of groundwater pumpage from Biscayne Aquifer.
Continuing trend of water conservation and protection of recharge areas. Little to no change in groundwater levels related to curtain wall-mediated waterflow changes.
Extent of saltwater intrusion inland based directly on regional sea level rise and groundwater pumping scenarios.
Scenario 2
Regional sea level rise of 2.49 ft (0.76 m) with 1%
annual chance flood of 5.45 ft (1.66 m).
Urbanization continues on trend with current levels.
Moderate increase in impacts from urbanization mitigated by continued degree of regulation, protection, and technological developments.
Groundwater pumpage at increased rate from Biscayne Aquifer due to elevated demand from urban expansion and agriculture, which is exacerbated by climate-change-driven events.
Pumpage mitigated to some extent by continuing trend of water conservation and protection Extent of saltwater intrusion inland based directly on regional sea level rise and groundwater pumping scenarios.
Exhibit 16
96 of recharge areas.
Moderate decrease in groundwater levels related to curtain wall-mediated waterflow changes.
Scenario 3
Regional sea level rise of 4.53 ft (1.38 m) with 1%
annual chance flood of 7.48 ft (2.28 m)
Urbanization rates higher than predicted by Florida 2070 (Carr and Zwick 2016, entire)
Declining water quality resulting from increased urbanization, limited regulation and restrictions, and overall reduced protections.
Limited development and adoption of new technology.
Groundwater pumpage greatly increased from Biscayne Aquifer due to demand from urban expansion, which is exacerbated by climate-change-driven drought events.
Limited practice of water conservation and protection of recharge areas.
Significant reduction in groundwater levels related to curtain wall-mediated waterflow changes.
Extensive inland saltwater intrusion as a result of high regional sea level rise, significant freshwater drawdown, and significant alteration of aquifer flow dynamics from curtain wall and other water management activities.
Scenario 4
Regional sea level rise of 1.41 ft (0.43 m) with 1%
annual Urbanization continues on trend with current levels, but with more compact Moderate impacts from increased urbanization significantly mitigated by use Increased groundwater pumpage from Biscayne Aquifer significantly Saltwater intrusion does not progress significantly inland from current Exhibit 16
97 chance flood of 4.36 ft (1.33 m) pattern of development and increased protected lands.
of improved technologies, increased regulation, and implementation of additional restrictions and protective measures.
mitigated by water conservation
- programs, protection of recharge areas, and advances in technology and water management practices. No impact on groundwater levels from curtain wall-mediated waterflow changes.
location due to development of infrastructure, technology, and other water management practices that mitigate or prevent saltwater intrusion.
5.1.1 Scenario 1: Continuation of Current Trends The first future scenario evaluates the continuation of current trends (i.e., a status quo scenario),
specifically with regards to sea level rise, land use change, freshwater contamination, groundwater loss, and saltwater intrusion within the range of Miami cave crayfish and their effects on the 3Rs of the species. This scenario assumes a regional sea level rise of approximately 2.49 ft (0.76 m) with a 1% annual chance flood of 5.45 ft (1.66 m) as projected for the Miami region in 2070 under the Intermediate-High scenario from Sweet et al. (2017, pp. 39-41). Concurrently, continuation of urban growth was predicted by the Florida 2070 Trend map, which reflects the land use pattern most likely to occur if the 2070 projections of a 40.79 percent increase in Miami-Dade Countys population is met and Miami-Dade County develops at its 2010 gross development density (13.58 people per acre) (Carr and Zwick 2016, pp. 1, 4, 5, 8-10, 24, 25, 30, 32). Under this scenario, we posit that anthropogenic water contamination of the Biscayne Aquifer will continue at its current levels in relation to development, agricultural land use, and protection of conservation areas predicted by the Florida 2070 Trend map. Water quality will be moderated by the current level of regulation and oversight, including protective standards, requirements, and utilization of basic technologies for effluent treatment. Freshwater demand from the growing population of South Florida will result in a trend of groundwater pumpage from the Biscayne Aquifer in alignment with current rates of water removal. We assume that water conservation strategies and protection of recharge areas will continue much as they do today, mitigating to some degree the loss of aquifer reserves from pumping and reduced recharge in areas with impervious land cover. Scenario 1 assumes little to no change in groundwater levels on the Atlantic Coastal Ridge related to any alteration in Biscayne Aquifer flow dynamics affected by the curtain wall extending to the west. On the basis of the regional sea Exhibit 16
98 level rise and the continued loss of freshwater volume within the Biscayne Aquifer delineated by this scenario, the extent of saltwater intrusion is predicted to move inland at rates similar to the present movement of the saltwater interface (Hughes and White 2016, pp. 1-2; Prinos et al. 2014, pp. 12-20).
5.1.2 Scenario 2: Continuation of Current Trends with Moderate Increases in Aquifer Drawdown and Contamination.
Scenario 2 assesses the continuation of current trends with regards to sea level rise and land use change, but with a more moderate increase in freshwater contamination, groundwater loss, and saltwater intrusion than the status quo projection represented by Scenario 1. As in the first scenario, Scenario 2 predicts a regional sea level rise of approximately 2.49 ft (0.76 m) with a 1% annual chance flood of 5.45 ft (1.66 m) (i.e., Intermediate-High scenario of Sweet et al.
2017, pp. 39-41) in conjunction with continuation of urban growth per the Florida 2070 Trend map (Carr and Zwick 2016, pp. 1, 4, 5, 8-10, 24, 25, 30, 32). However, under Scenario 2, we assume a slightly larger increase in the impacts from urbanization on groundwater quality, which are mitigated to some degree by levels of regulation, protection, and technological developments continuing similarly to those of today. In addition, elevated demand from urban expansion and agriculture, which is exacerbated by climate-change-driven events (e.g., more frequent or intense droughts possibly of longer duration), will drive water withdrawal rates higher. This increased groundwater pumpage will only be mitigated to some extent by a continuing trend of water conservation and protection of recharge areas. Scenario 2 further predicts that a moderate decrease in groundwater levels will occur within the Biscayne Aquifer in the Atlantic Coastal Ridge as a direct consequence of curtain wall-mediated waterflow changes. Since the extent of saltwater intrusion is dependent on both the regional sea level rise and freshwater loss from the Biscayne Aquifer in this scenario, the saltwater interface is expected to move farther inland than it does under Scenario 1 (Hughes and White 2016, pp. 1-2; Prinos et al. 2014, pp. 12-20).
5.1.3 Scenario 3: Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion The third scenario we evaluated explores the effects of increasing rates of regional sea level rise, urbanization, freshwater contamination, aquifer drawdown, and saltwater intrusion on the 3Rs of Miami cave crayfish (i.e., a lower bound, pessimistic scenario). Scenario 3 projects a regional sea level rise of 4.53 ft (1.38 m) with a 1% annual chance flood of 7.48 ft (2.28 m) in the Miami area by 2070 as predicted by the Extreme scenario from Sweet et al. (2017, pp. 39-41).
Scenario 3 also assumes a higher rate of urban growth than that predicted by the Florida 2070 Trend map and a greater gross development density than that reported in 2010 (i.e., > 13.58 people per acre) (Carr and Zwick 2016, pp. 1, 4, 5, 8-10, 24, 25, 30, 32). We approximated this pattern of land use change by reclassifying the Other category of land depicted in the Florida Exhibit 16
99 2070 Trend map as Developed (Carr and Zwick 2016, p. 24). Accordingly, increased development would lead to elevated water contamination from anthropogenic sources. We concurrently assumed that limited regulation, restrictions, and overall reduced protections pertaining to water and air pollution would be unable to significantly mitigate the higher levels of groundwater contamination. Similarly, limited development and/or adoption of new technology (e.g., advanced filtration systems for flow-through water operations) would curtail the efficacy of technological prevention of aquifer contamination. In alignment with high rates of development, groundwater pumpage from the Biscayne Aquifer would greatly increase, significantly expanding to meet the demands buoyed by climate change-related drought events.
Under this scenario, groundwater levels would also be significantly reduced from the limited practice of water conservation, lost protection of recharge areas, and curtain wall-mediated waterflow changes. Consequently, there would be extensive saltwater intrusion within the Atlantic Coastal Ridge, the saltwater interface driven far inland by high regional sea level rise, significant freshwater drawdown, and substantial alteration of aquifer flow dynamics by the curtain wall.
5.1.4 Scenario 4: Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise Scenario 4 evaluates the continuation of current trends of urbanization and aquifer drawdown and contamination on the 3Rs of Miami cave crayfish, but assumes that conservation measures will be implemented to minimize the impacts of these factors and that regional sea level rise will be within the lower range of plausible climate change scenarios (i.e., an upper bound optimistic scenario). In this fourth scenario, we predicted a regional sea level rise of 1.41 ft (0.43 m) with a 1% annual chance flood of 4.36 ft (1.33 m) for the Miami region in 2070 per the Intermediate scenario from Sweet et al. (2017, pp. 39-41). In terms of land use, we posited that urbanization would continue on trend with current levels, but with a more compact pattern of development and increased protected lands. In order to represent this urban growth, we used the 2070 Alternative scenario (Carr and Zwick 2016, pp. 10-13, 24, 25). In contrast to the 2070 Trend scenario, the 2070 Alternative scenario modeled: 1. some of the 2070 population growth within pre-existing densities of developed areas, 2. a development density 20 percent higher than that assumed by the 2070 Trend scenario, and 3. protected lands within 2016 Florida Managed Areas (the only protected lands in the 2070 Trend scenario), 2015 Florida Forever project lands, and Florida Ecological Greenways Network Priorities 1 & 2 (Carr and Zwick 2016, pp. 10-11).
Scenario 4 predicted that moderate impacts to water quality from increased urbanization on the Atlantic Coastal Ridge would be significantly mitigated by the use of improved technologies (e.g., improved connector systems to prevent septic tank leakage), increased regulation, and implementation of additional restrictions and protective measures to protect air and water quality. Likewise, elevated groundwater pumpage from the Biscayne Aquifer would be substantially offset by water conservation programs, increased protection of recharge areas, and advances in technology and water management practices (e.g., water recycling). The curtain wall Exhibit 16
100 would be constructed and maintained in such a way as to prevent any adverse impact on groundwater levels from waterflow changes within the aquifer system. Finally, this scenario predicts that saltwater intrusion would not progress significantly inland from its 2018 location due to lower comparative regional sea level rise, negligible changes in freshwater levels within the Biscayne Aquifer, and the development of infrastructure, technology, and other water management practices that mitigate or prevent saltwater intrusion along the coast and canal systems of the Atlantic Coastal Ridge.
5.2 Future Conditions We forecasted the 3 Rs for Miami cave crayfish under each of the four scenarios detailed above.
We analyzed the future condition of Miami cave crayfish resiliency using the same four metrics derived from the species needs that we assessed in the current conditions analysis: 1. quantity of karstic limestone aquifer habitat, 2. food availability, 3. freshwater quality related to anthropogenic contamination, and 4. freshwater availability related to saltwater intrusion (Table 4.2).
The supporting material used to inform each 2070 scenario (e.g., Florida 2070, regional sea level projections from Sweet et al. 2017, entire and Sweet et al. 2018, entire) did not provide sufficient data on which to construct quantitative measures analogous to those estimated in the current conditions analysis. However, we were able to use the detailed future scenario descriptions above to evaluate each population resiliency factor based on qualitative projections of the same variables employed to assess them in the current conditions analysis. Accordingly, we were able to classify all of the population resiliency factors into high, moderate, and low categories under the four future scenarios for each analysis unit of Miami cave crayfish and for the species overall using the same system of percentage ranges used in the current conditions analysis (Table 4.2). We used the same methodology described in Section 4.1.5 and Appendix E to combine the values of Quality of Surface Cover, Freshwater Quality, Freshwater Availability, and the Habitat Quantity factor to calculate a Combined Habitat value, which we used as a representative measure of the resiliency of each analysis unit of Miami cave crayfish.
5.2.1 Scenario 1: Continuation of Current Trends 5.2.1.1 Resiliency Under Scenario 1 in 2070, we predict that six analysis units of Miami cave crayfish will have low resiliency and one (analysis unit 5) will likely be extirpated as the result of extensive saltwater intrusion (Table 5.2.1). Although urban expansion and its accompanying infrastructure (e.g., sewer and water lines) will result in the direct loss of karstic limestone habitat within the range of all Miami cave crayfish analysis units, the development will also serve to limit the Exhibit 16
101 growth of limestone quarrying operations on the Atlantic Coastal Ridge. Continuing trends of groundwater pumpage from the Biscayne Aquifer will likely reduce freshwater levels, but water conservation and protection of recharge areas combined with a negligible curtain wall-related change in groundwater levels will mitigate a significant portion of the freshwater loss.
Consequently, the quantity of karstic limestone aquifer habitat available to all analysis units of the species will remain above 80 percent of the habitat that would have been available to Miami cave crayfish in the absence of anthropogenic influence.
However, as development spreads across the region, all analysis units will experience elevated levels of anthropogenically-sourced groundwater pollution and loss of detrital input from reductions in natural vegetative cover and proliferation of impervious surfaces. As a result, we predict that all Miami cave crayfish analysis units will exhibit low resiliency factors linked to degrading quality of surface cover and quality of the freshwater within their subterranean habitats. Under this scenario, the progression of the saltwater interface inland by 2070 is projected to intrude into the Biscayne Aquifer below at least 20 percent of the surface area encompassing analysis units 1, 2, and 3 and at least 50 percent of the surface area encompassing analysis units 6 and 7. We predict that saltwater almost entirely or completely occupies the aquifer within the range of analysis unit 5 such that these Miami cave crayfish will be extirpated by 2070. Only the more landward analysis unit 4 with access to higher elevation environments will remain minimally effected by saltwater intrusion. Consequently, under scenario 1, habitat conditions and the linked resiliency of all Miami cave crayfish analysis units will decline in relation to the species current condition, such that analysis units 1, 2, 3, 4, 6, and 7 will exhibit low resiliency, analysis unit 5 is likely to be extirpated, and the species overall will have lower resiliency than it does currently (Table 5.2.1).
Table 5.2.1. Predicted habitat factors and future resiliency of Miami cave crayfish in 2070 under scenario 1.
Analysis Unit Habitat Quantity Factor Habitat Quality Factors Resiliency Score Quality of Surface Cover Freshwater Quality (Anthropogenic Contamination Measure)
Freshwater Availability (Saltwater Intrusion Measure)
Combined Habitat Quality Factor 1
High Low Low Moderate Low Low 2
High Low Low Moderate Low Low 3
High Low Low Moderate Low Low 4
High Low Low High Low Low Exhibit 16
102 5
High Low Low Extirpated Extirpated Extirpated 6
High Low Low Low Low Low 7
High Low Low Low Low Low 5.2.1.2 Redundancy In 2070, we predict that Miami cave crayfish will have low redundancy for the same reasons outlined in our current conditions analysis. The extirpation of analysis unit 5 will further decrease the redundancy of the species.
5.2.1.3 Representation Although Miami cave crayfish have evidenced some adaptability in their capacity to be maintained and reproduce in captive settings, within the next 50 years, the subterranean species is unlikely to evolve the ability to sustain populations within surface aquatic habitats due to its morphological adaptations to subterranean environments (Section 2.1) and the water temperature and quality restraints on its survival (Section 2.5.3). Similarly, the species is unlikely to sustain long-term, viable populations of significant size in the suboptimal habitats of the Biscayne Aquifer outside of the Atlantic Coastal Ridge (Section 2.5). Pending the discovery of genetic, morphologic, and/or ecological diversity presently undescribed for the species, we therefore project that Miami cave crayfish will have low representation in 2070. The anticipated loss of analysis unit 5 under this future scenario will further lower the degree of representation exhibited by the species in comparison to its current condition.
5.2.2 Scenario 2: Continuation of Current Trends with Moderate Increases in Aquifer Drawdown and Contamination 5.2.2.1 Resiliency Under Scenario 2, we predict that six analysis units of Miami cave crayfish will have low resiliency and one (analysis unit 5) will likely be extirpated as the result of extensive saltwater intrusion (Table 5.2.2). Similar to scenario 1, we predict that growth of development and heightened freshwater withdrawal from the Biscayne Aquifer will result in additional loss of karstic limestone aquifer habitat in the range of all analysis units of the species, but we do not expect the amount to drop below 80 percent of the habitat that would have been available to Miami cave crayfish in the absence of anthropogenic influence.
Exhibit 16
103 Urbanization-driven increases in groundwater contamination, impervious land cover, and destruction of natural vegetation will result in lowered resiliency among all analysis units from the subsequent loss of detrital input into subterranean ecosystems and compromised freshwater quality. In comparison to scenario 1, groundwater levels are predicted to be lower from increased freshwater withdrawal and curtain wall-related changes to water flow in the aquifer system along the Atlantic Coastal Ridge. As a result, saltwater intrusion pushes farther inland by 2070 under scenario 2. Accordingly, we project that saltwater intrusion will underlay at least 20 percent of the surface area of analysis units 1 and 2 and at least 50 percent of the surface area of analysis units 3, 6, and 7. Saltwater will almost entirely or completely occupy the Biscayne Aquifer within the range of analysis unit 5 such that this analysis unit will likely be extirpated by 2070.
In contrast, analysis unit 4 will remain relatively unaffected by saltwater intrusion. Overall, the resiliency of Miami cave crayfish will be lower in scenario 2 than in either the current condition or scenario 1. Analysis units 1, 2, 3, 4, 6, and 7 are predicted to exhibit low resiliency, analysis unit 5 will likely be extirpated, and the species as a whole will demonstrate low resiliency (Table 5.2.2).
Table 5.2.2. Predicted habitat factors and future resiliency of Miami cave crayfish in 2070 under scenario 2.
Analysis Unit Habitat Quantity Factor Habitat Quality Factors Resiliency Score Quality of Surface Cover Freshwater Quality (Anthropogenic Contamination Measure)
Freshwater Availability (Saltwater Intrusion Measure)
Combined Habitat Quality Factor 1
High Low Low Moderate Low Low 2
High Low Low Moderate Low Low 3
High Low Low Low Low Low 4
High Low Low High Low Low 5
High Low Low Extirpated Extirpated Extirpated 6
High Low Low Low Low Low 7
High Low Low Low Low Low 5.2.2.2 Redundancy Exhibit 16
104 As in scenario 1, we predict that Miami cave crayfish will have low redundancy in 2070, exacerbated by the loss of analysis unit 5.
5.2.2.3 Representation As discussed in scenario 1, we predict that Miami cave crayfish will have low representation in 2070 under scenario 2. The likely extirpation of analysis unit 5 will contribute significantly to the lower representation exhibited by the species in relation to its current degree of representation.
5.2.3 Scenario 3: Elevated rates of regional sea level rise, urbanization, freshwater contamination and loss, and saltwater intrusion 5.2.3.1 Resiliency Under Scenario 3, we predict that four analysis units of Miami cave crayfish will have low resiliency and three analysis units will likely be extirpated as the result of extensive saltwater intrusion by 2070 (Table 5.2.3). Despite constraining the expansion of limestone quarrying operations on the Atlantic Coastal Ridge, extensive development and its attendant subterranean infrastructure will likely eliminate a significant portion of the karstic limestone within the range of each Miami cave crayfish analysis unit. Concurrently, the groundwater flowing through the remaining limestone in the region will likely drop well below current levels as elevated freshwater removal from the aquifer, curtain wall-related losses, and inadequate recharge go unchecked by lax protections and limited water conservation practices. As a result, all Miami cave crayfish analysis units experience a reduction of their karstic limestone aquifer habitat below 80 percent (but not below 50 percent) of the habitat that would have been available in the absence of anthropogenic influence.
In addition, we predict that all analysis units will experience greatly elevated levels of groundwater contamination and loss of detrital input from urban expansion that progresses largely unchecked by regulatory, conservation behavioral, or technological advancements.
Consequently, Miami cave crayfish analysis units will likely exhibit lower resiliency factors related to poor quality of both surface cover and freshwater in comparison to their current condition and those projected by scenarios 1 and 2. Scenario 3s extensive inland intrusion of the saltwater interface causes the likely extirpation of analysis units 5, 6, and 7, while analysis units 1, 2, 3, and 4 all experience significant impacts from saltwater intrusion by 2070. For the four analysis units that remain viable, we expect that saltwater intrusion will spread below at least 50 percent of the surface area of their ranges. Under this scenario, habitat conditions and the linked resiliency of all Miami cave crayfish analysis units will likely deteriorate below those of any other future scenario and in relation to the species current condition. Analysis units 1, 2, 3, and Exhibit 16
105 4 will exhibit low resiliency, while analysis units 5, 6, and 7 are predicted to be completely extirpated (Table 5.2.3).
Table 5.2.3. Predicted habitat factors and future resiliency of Miami cave crayfish in 2070 under scenario 3.
Analysis Unit Habitat Quantity Factor Habitat Quality Factors Resiliency Score Quality of Surface Cover Freshwater Quality (Anthropogenic Contamination Measure)
Freshwater Availability (Saltwater Intrusion Measure)
Combined Habitat Quality Factor 1
Moderate Low Low Low Low Low 2
Moderate Low Low Low Low Low 3
Moderate Low Low Low Low Low 4
Moderate Low Low Low Low Low 5
Moderate Low Low Extirpated Extirpated Extirpated 6
Moderate Low Low Extirpated Extirpated Extirpated 7
Moderate Low Low Extirpated Extirpated Extirpated 5.2.3.2 Redundancy With the extirpation of analysis units 5, 6, and 7, we predict that Miami cave crayfish will have lowest level of redundancy in 2070 under scenario 3. The loss of three of the seven analysis units of the species will result in much lower redundancy than that currently exhibited by Miami cave crayfish and that projected under scenarios 1 and 2.
5.2.3.3 Representation Exhibit 16
106 We predict that Miami cave crayfish will experience the lowest level of representation under scenario 3 in comparison not only to the species current condition, but also to that under the three other plausible future scenarios described in this chapter. The expected loss of analysis units 5, 6, and 7 by 2070 will substantially lower any potential adaptive capacity of the species overall.
5.2.4 Scenario 4: Continuation of Current Trends with Increased Conservation Measures and Lower Sea Level Rise 5.2.4.1 Resiliency Under the fourth and final future scenario, all seven analysis units of Miami cave crayfish are predicted to have low resiliency in 2070 (Table 5.2.4). Although urban expansion and its direct and indirect adverse impacts on the quantity and quality of Miami cave crayfish habitat continues in scenario 4, increased environmental regulations and protections in conjunction with advancement in technology and conservation-related behaviors will largely mitigate the negative influences acting on Miami cave crayfish analysis units. Some loss of karstic limestone and minimal decline of freshwater reserves in the Biscayne Aquifer likely will not be significant enough to drop the amount of habitat available to all analysis units of the species below 80 percent of the habitat that would have been available to Miami cave crayfish in the absence of anthropogenic influence.
Similarly, continued loss of surface vegetation, permeable surfaces, and groundwater quality from anthropogenic pollution likely will lower the resiliency of analysis units compared to their current condition, but not as substantially as was the case in scenarios 1, 2, and 3. Under scenario 4, saltwater intrusion does not progress significantly inland from its current location due to the development of infrastructure, technology, and other water management practices that minimize or prevent its incursion. Consequently, Miami cave crayfish analysis units do not experience elevated threats from an inland shift in the saltwater interface to the extent that any analysis units are extirpated as in the other future scenarios. All analysis units of the species continue to exhibit the same degree of low resiliency attributable to this factor as do current analysis units. For this reason, habitat-related resiliency of all Miami cave crayfish analysis units will decline slightly in relation to the species current condition, but no analysis units are predicted to be extirpated and the species overall will exhibit low resiliency (Table 5.2.4).
Table 5.2.4. Predicted habitat factors and future resiliency of Miami cave crayfish in 2070 under scenario 4.
Habitat Quality Factors Exhibit 16
107 Analysis Unit Habitat Quantity Factor Quality of Surface Cover Freshwater Quality (Anthropogenic Contamination Measure)
Freshwater Availability (Saltwater Intrusion Measure)
Combined Habitat Quality Factor Resiliency Score 1
High Low Low High Low Low 2
High Low Low High Low Low 3
High Low Low Moderate Low Low 4
High Low Low High Low Low 5
High Low Low Low Low Low 6
High Low Low Moderate Low Low 7
High Low Low Low Low Low 5.2.4.2 Redundancy For scenario 4, we predict that Miami cave crayfish will have low redundancy for the same reasons outlined in our current condition analysis. Since we do not expect any analysis units will be extirpated by 2070, the future redundancy of the species remains approximately the same as current redundancy and is not as low as that projected under the other three future scenarios that we evaluated in this chapter.
5.2.4.3 Representation For the same reasons we reviewed in scenario 1, we expect that Miami cave crayfish will have low representation in 2070 under scenario 4. However, the persistence of all seven analysis units of the species leads us to conclude that this future scenario presents the best opportunity of all four plausible scenarios for maintaining what little representation is evidenced by current Miami cave crayfish into the future.
5.3 Summary of Future Conditions We evaluated four scenarios, including a status quo scenario, to characterize the uncertainty regarding plausible futures for Miami cave crayfish within a 50-year timeframe. The 3Rs were predicted for each scenario, which employed differing combinations of three possible regional sea level rise scenarios (per Sweet et al. 2017, entire and Sweet et al. 2018, entire), three levels Exhibit 16
108 of urbanization modified from Florida 2070 (Carr and Zwick 2016, entire), various freshwater quality and quantity scenarios we defined for the Biscayne Aquifer, and four possible extensions of the saltwater interface along the Atlantic Coastal Ridge. Inland extension of the saltwater interface was projected to extirpate one analysis unit (analysis unit 5) in two scenarios and three analysis units (analysis units 5, 6, and 7) in another scenario by 2070. The only scenario in which all analysis units of the species persisted entailed a significant degree of conservation initiatives related to urban planning, water management, aquifer protection, and habitat preservation. In the four future scenarios assessed, representation, redundancy, and resiliency for all analysis units and the species overall were low and each had declined in comparison to the current condition of Miami cave crayfish (Table 5.3).
Table 5.3. Comparison of the current resiliency for each analysis unit of Miami cave crayfish (evaluated in Chapter 4) with the predicted resiliency of each analysis unit of the species in 2070 under four plausible future scenarios.
Analysis Unit Current Future Scenario 1 Scenario 2 Scenario 3 Scenario 4 1
Low Low Low Low Low 2
Low Low Low Low Low 3
Low Low Low Low Low 4
Low Low Low Low Low 5
Low Extirpated Extirpated Extirpated Low 6
Low Low Low Extirpated Low 7
Low Low Low Extirpated Low 5.4 Summary of Species Viability This species status assessment describes the viability of the Miami cave crayfish in terms of representation, redundancy, and resiliency by using the best commercial and scientific information available. We used these parameters to describe current and potential future conditions regarding the species viability. To address the uncertainty associated with potential future impacts and how they will affect the species specific needs, we evaluated potential future conditions using four plausible scenarios. These scenarios were based on a variety of negative Exhibit 16
109 and positive influences on the species across each of its seven analysis units, allowing us to predict potential changes in each analysis unit on the basis of habitat parameters.
Several factors influence the viability of Miami cave crayfish, all of which relate directly to the species needs. Destruction or reduction of their karstic limestone aquifer habitat due to development, limestone extraction activities, and freshwater drawdown negatively affects current analysis units, with more significantly impacts likely for future ones. Anthropogenically-sourced groundwater contamination and loss of detrital input into aquifer ecosystems are also important influences on the species now and into the future. Finally, saltwater incursion into the Biscayne Aquifer currently impacts the species and proves to be the largest factor affecting the future persistence of Miami cave crayfish analysis units.
5.4.1 Resiliency We assessed seven analysis units of the species within its narrow endemic range. These analysis units are all within habitats that have been highly modified by anthropogenic influence as well as natural processes driving saltwater intrusion and fluctuations in freshwater volume within the Biscayne Aquifer. The overall poor quality of their current habitat imparts low resiliency to all analysis units of Miami cave crayfish such that the species has low resiliency to environmental and demographic stochasticity. Three out of four plausible future scenarios predict at least one analysis unit to become extirpated by 2070. In all future scenarios evaluated, Miami cave crayfish habitat and, therefore, the interconnected resiliency of the species, declines in condition over 50 years. Consequently, the species loses resiliency in the future, especially under the three scenarios in which analysis units become extirpated, and will be poorly suited to persist when confronted with environmental or demographic stochasticity and disturbances.
5.4.2 Redundancy Species redundancy for the Miami cave crayfish is low and will continue to be low into the future. At present, the species has seven analysis units within a highly restricted endemic range in the Biscayne Aquifer on one portion of the Atlantic Coastal Ridge in Miami-Dade County.
The species narrow range and the high degree of connectivity of the Biscayne Aquifer system portends that any catastrophic event in the region would have an extensive impact on all Miami cave crayfish populations concurrently. On the basis of habitat conditions, two plausible future scenarios predict analysis unit 5 will become extirpated by 2070, while another projects that three analysis units (analysis units 5, 6, and 7) will be lost in the next 50 years. Subsequently, the already low redundancy of Miami cave crayfish will decline in the future, further reducing the species capacity to withstand any of the catastrophic events we identified earlier.
Exhibit 16
110 5.4.3 Representation The Miami cave crayfishs narrow endemic range confers inherently limited representation to the species. Since information is not available regarding the species genetic, morphological, or ecological niche, which are typical measures of species representation, we evaluated the Miami cave crayfish as a single representative unit with low current representation. The extirpation of at least one analysis unit in three of the four plausible future scenarios means that the degree of representation exhibited by Miami cave crayfish will most likely decline over the next 50 years, making the species less adaptive to novel changes in its biological and physical environment.
Exhibit 16
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Exhibit 16
127 APPENDIX A: PRESUMED INFLUENCE DIAGRAM FOR MIAMI CAVE CRAYFISH Presumed influence diagram for the Miami cave crayfish. Blue ovals represent the primary sources of influence; green rectangles describe the specific influential factors; orange ovals represent the species needs (section 2.7); and yellow rectangles represent the demographic components of the population factors of species needs (section 2.7). Chapter 3 provides a more detailed explanation of these linkages.
Exhibit 16
128 Exhibit 16
129 APPENDIX B: AGRICULTURAL LAND USE IN ENDEMIC RANGE OF MIAMI CAVE CRAYFISH The table below summarizes the extent of coverage (in acres) and the number of land units represented by nine distinct types of agricultural land use for each analysis unit of Miami cave crayfish and across the entire endemic range of the species. Values were calculated by GIS analyses on the land use data for Miami-Dade County generated by the research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a). Categorizations are per Miami-Dade County (2021a). Agriculture, Other includes exotic birds, monkeys, and research facilities. Farm Storage Areas are storage structures or lots for farm implements. Fish Farms include tropical fish aquariums, fish, and alligator farms. Pasture includes grazing, animal farming, dairy farms and animal feed lots, but excludes horse and poultry activities. Plant Nurseries include sod farms and ornamental nurseries.
Land Use Analysis Unit 1 Analysi s Unit 2
Analysi s Unit 3
Analy sis Unit 4 Analy sis Unit 5 Analysi s Unit 6
Analysi s Unit 7
All Analysi s Units Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Agricultur e, Other.
0.59 53 1
23.
046 7
9 11.
263 4
3 0 0 0 0 0 0 0 0 34.
905 6
1 3
Farm Storage Areas.
134.
4952 5
3 118
.99 23 1
1 0
41.
128 8
2 9
0 0 0 0 0 0 0 0 294
.61 63 1
9 2
Fish Farms.
2.34 8576 1
82.
954 03 1
4 5.6 738 25 1 0 0 0 0 0 0 0 0 90.
976 432 1
6 Groves.
3969
.323 8
3 7
2 567 8.0 047 9
0 2
189 0.6 259 2
1 6
12.
50 50 5 0 0 16.
506 1
7 0 0 115 66.
965 5
1 5
0 2
Horse Training and Stables.
22.3 013 3
284
.94 45 8
2 38.
810 6
1 0
16.
69 31 6 0 0 0 0 0 0 362
.74 95 1
0 1
Pasture.
51.0 377 6
124
.51 60 5
9 94.
997 8
2 7
0 0 34.
75 00 1 0 0 0 0 305
.30 16 9
3 Plant Nurseries.
2272
.829 6
2 3
9 691 4.3 893 8
6 0
261 3.3 370 2
4 1
48.
53 07 1
3 0
0 0 0 3.3 903 1 118 52.
1 3
Exhibit 16
130 476 8
5 4
Poultry.
0 0
17.
641 9
5 17.
150 5
3 0 0 0 0 0 0 0 0 34.
792 4
8 Row and Field Cropland.
5621
.368 6
3 6
2 368 5.9 169 3
6 6
293 8.4 266 2
0 5
36.
48 33 8 0 0 0 0 0 0 122 82.
195 5
9 4
1 All Types.
1207 4.30 1
0 3
7 169 30.
41 2
4 0
7 765 1.4 1
7 3
5 11 4.2 1
3 2
34.
75 1 16.
51 7 3.3 9
1 368 24.
98 4
2 2
0 The bar graph below depicts the acreage covered by each type of agricultural land use for each analysis unit of Miami cave crayfish. Values were calculated by GIS analyses on the land use data for Miami-Dade County generated by the research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a). Categorizations were per Miami-Dade County (2021a). Agriculture, Other includes exotic birds, monkeys, and research facilities. Farm Storage Areas are storage structures or lots for farm implements. Fish Farms include tropical fish aquariums, fish, and alligator farms. Pasture includes grazing, animal farming, dairy farms and animal feed lots, but excludes horse and poultry activities. Plant Nurseries include sod farms and ornamental nurseries.
Exhibit 16
131 Exhibit 16
132 APPENDIX C: PRECIPITATION CHANGE PROJECTIONS Climate change will greatly influence future precipitation dynamics across south Florida. are of great importance to climate data users in South Florida. The projections below represent output from ensemble climatemodel simulations reported by Infanti et al. 2019. These predictions capture the variability in wet and dry events across seasons and annually for the endemic range of Miami cave crayfish.
Below is a matrix of nearterm (NT, 2019-2045), middleterm (MT, 2046-2072), and long term (LT, 2073-2099) changes in precipitation parameters (dry events, wet events, neutral events, and no threshold) for October-March (ONDJFM), April-September (AMJJAS), and the annual mean. Matrix is for the full suite of RCP 4.5 data. Changes are presented in percent change in the given period from 1974-2000 (shading) and in mm/day (contours). This matrix includes all available downscaled biascorrected spatially disaggregated (BCSD) data. Figure from Infanti et al. 2020 (p. 7).
Below is a matrix of nearterm (NT, 2019-2045), middleterm (MT, 2046-2072), and long term (LT, 2073-2099) changes in precipitation parameters (dry events, wet events, neutral events, and no threshold) for October-March (ONDJFM), April-September (AMJJAS), and the annual mean. Matrix is for the full suite of RCP 8.5 data. Changes are presented in percent change in the given period from 1974-2000 (shading) and in mm/day (contours). This matrix includes all Exhibit 16
133 available downscaled biascorrected spatially disaggregated (BCSD) data. Figure from Infanti et al. 2020 (p. 9).
Exhibit 16
134 APPENDIX D: PROTECTED LAND IN ENDEMIC RANGE OF MIAMI CAVE CRAYFISH The table below summarizes the extent of coverage (in acres) and the number of land units represented by five types of protected land for each analysis unit of Miami cave crayfish and across the entire endemic range of the species. Values were calculated by GIS analyses on the land use data for Miami-Dade County generated by the research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a).
Categorizations are per Miami-Dade County (2021a). Other Nature Preserves and Protected Areas include state mangrove preserves, Turkey Point Wilderness Area, Big Cypress Swamp Preserves, and acquired government owned Environmentally Endangered Land (EEL) Covenant sites. Vacant, Protected, Government-Owned or controlled includes EEL sites. Vacant, Protected, Privately-Owned are privately-owned proposed and designated EEL sites that have yet to be acquired and/or sites protected under any other conservation or environmental mechanism.
Total Not in Private Ownership include County Operated Parks, Other Nature Preserves and Protected Areas, and Vacant, Protected, Government-Owned or controlled sites. Wellfields are not included in this calculation since they are distributed across a range of public and private ownership. EEL sites that were classified as released or expired were excluded.
Land Use Analysi s Unit 1
Analysi s Unit 2
Analysi s Unit 3
Analysi s Unit 4
Analysi s Unit 5
Analysi s Unit 6
Analysi s Unit 7
All Analys is Units Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land Coverage of Habitat
- Land County Operated Parks.
294
.02 00 6 396
.99 97 1
9 178
.36 79 1
7 164 1.6 423 3
6 0.4 959 1 71.
468 6
1 4
489
.09 96 3
3 307 2.0 939 1
2 6
Other Nature Preserves and Protected Areas.
296
.39 86 1
5 411
.37 58 1
5 219
.46 40 1
0 224
.57 9
7 266
.19 64 1
1 240
.70 18 8 17.
904 0
1 2
167 6.6 196 7
8
- Vacant, Protected, Governmen t-Owned or controlled.
10.
022 3
1 69.
450 9
3 28.
443 1
1 0
0 0 14.
318 9
1 0 0 0 0 122
.23 52 1
5
- Vacant, Protected, Privately-Owned.
144
.49 57 2
3 76.
007 1
7 87.
458 8
2 3
0 0 177
.08 87 8 1.7 082 2 0 0 486
.75 85 7
3 Wellfields.
100
.75 11 2 0 0 0 0 173
.94 07 4 0 0 0 0 10.
607 7
2 285
.29 95 8
Exhibit 16
135 Total Not in Private Ownership.
600
.44 2
2 877
.83 3
7 426
.28 3
7 186 6.2 2
4 2
281
.01 1
3 312
.17 2
2 507
.00 4
5 487 0.9 5
2 1
9 Total Land Under Some Degree of Protection.
845
.69 4
7 953
.83 5
4 513
.73 6
0 204 0.1 6
4 6
458
.10 2
1 313
.88 2
4 517
.61 4
7 564 3.0 1
3 0
0 The bar graph below depicts the acreage covered by each type of agricultural land use for each analysis unit of Miami cave crayfish. Values were calculated by GIS analyses on the land use data for Miami-Dade County generated by the research section of the Regulatory and Economic Resources Departments Planning Division (Miami-Dade County 2021a). Categorizations were per Miami-Dade County (2021a). Other Nature Preserves and Protected Areas include state mangrove preserves, Turkey Point Wilderness Area, Big Cypress Swamp Preserves, and acquired government owned Environmentally Endangered Land (EEL) Covenant sites. Vacant, Protected, Government-Owned or controlled includes EEL sites. Vacant, Protected, Privately-Owned are privately-owned proposed and designated EEL sites that have yet to be acquired and/or sites protected under any other conservation or environmental mechanism. EEL sites that were classified as released or expired were excluded.
Exhibit 16
136 APPENDIX E - CURRENT CONDITION METHODOLOGY We performed analyses in ArcGIS based on the most current data available from the literature, Miami-Dade County, and Esri to develop the current condition resiliency score for each analysis unit of Miami cave crayfish. A global map of land use/land cover for 2020 was released in July 2021 by Esri Inc. (Esri 2021). Land use data for Miami-Dade County is generated by the research section of the Regulatory and Economic Resources Departments Planning Division and is updated weekly (Miami-Dade County 2021a). Location data for septic sewers in Miami Dade County is also provided by Miami-Dade County and updated weekly based on Florida Department of Health in Miami-Dade County records (Miami-Dade County 2021b). The most recent map available for sewer line infrastructure within the endemic range of Miami cave crayfish was charted in 2018 by Miami-Dade County (Miami-Dade County 2018). Estimates for the depth of the Biscayne Aquifer across the Atlantic Coastal Ridge habitat of the species were taken from Hughes and White (2016, p. 26). The extent of saltwater intrusion into the Biscayne Aquifer in Miami-Dade County for 2018 was mapped according to Prinos (2019, entire).
Habitat Quantity - Quantity of Karstic Limestone Aquifer Habitat We estimated the quantity of karstic limestone aquifer habitat available to each analysis unit of Miami cave crayfish by first multiplying the depth of the Biscayne Aquifer across the Atlantic Coastal Ridge by the surface area of karstic limestone habitat currently available to the species within its endemic range. ArcGIS was used to map the depth of the Biscayne Aquifer for each analysis unit of Miami cave crayfish based on the estimates provided by Hughes and White (2016, p. 26). The depth of the Biscayne Aquifer varies temporally in response to precipitation events, groundwater pumping, evapotranspiration, water management, and other natural and anthropogenic hydrologic and hydraulic processes (Hughes and White 2016, p. 27). Therefore, we relied on the most recent (2016) and comprehensive (based on measurements from 133 wells) estimate of interpolated aquifer thickness available for Miami-Dade County (Hughes and White 2016, pp. 22, 27). However, it was not possible to delineate process-dependent measures of aquifer depth related to anthropogenic versus natural processes such that we used the same estimates of Biscayne Aquifer thickness for estimating the volume of both currently-available Miami cave crayfish habitat and habitat that would be accessible to the species in the absence of human influence.
We evaluated the surface area of karstic limestone habitat currently available to each analysis unit of Miami cave crayfish by analyzing a polygon feature class of existing land use within Miami-Dade County, which is constructed with aerial photography, property appraisal data, and development and environmental information assessed by the Regulatory and Economic Resources Departments Planning Division of Miami-Dade County (Miami-Dade County 2021a).
We downloaded the data that was last updated on July 21, 2021 into ArcGIS on July 22, 2021.
In order to replicate the actual karstic limestone habitat currently available to the species under Exhibit 16
137 current, we removed from our calculations any land use categories that represent the absence of this habitat, specifically: Coastal Waters (all classifications); Inland water bodies (all classifications); Remaining bay waters; Remaining ocean waters; Rivers and canals; and Extraction, Excavation, Quarrying, Rock-Mining, excluding the resulting water body. Since all classifications of Inland water bodies were associated wholly or partially with human construction activities, when calculating the karstic limestone aquifer habitat that would be accessible to the species in the absence of anthropogenic processes, we only excluded the following land use categories from our analyses: Coastal Waters (all classifications); Remaining bay waters; Remaining ocean waters; and Rivers and canals.
Miami-Dade County maintains approximately 4,100 miles of sewer lines, a significant number of which are excavated into and, therefore, eliminate potential karstic limestone aquifer habitat of Miami cave crayfish (Miami-Dade County 2021c). In order to account for this habitat loss, we analyzed the most recently-published shapefile of sewer line infrastructure developed by Miami-Dade County on October 5, 2018 (Miami-Dade County 2018). We downloaded the data into ArcGIS on 7/23/2021 and removed sewer lines that were identified as extending either aerially or subaqueously (i.e., ASSETTYPE=Aerial, Aerial FM, Subaqueous FM, or Subaqueous GM).
Measurements of the depth of burial were not available for any of the sewer lines and mean diameter of sewer line pipes ranged from less than 1 inch (0.03 m) to 120 inches (3.05 m) for 79,008 records included in the infrastructure shapefile (Miami-Dade County 2018). The mean diameter of sewer lines was 27.7 inches (0.7 m), which we used to calculate a buffer to represent the loss of karstic limestone aquifer habitat from sewer line infrastructure. Limestone substrate is removed to situate sewer line pipes, and interconnected networks of cavities within the limestone are clogged with the fillers (e.g., sand, cement) used to protect subterranean sewer lines from water damage (https://www.miamidade.gov/water/library/donation/part-4/PDF/GS_1_9.pdf). Therefore, we calculated a 7 ft (2.13 m; approximately three times 27.7 inches) wide and a 7 ft (2.13 m) deep buffer around each sewer line in the ArcGIS shapefile to represent a conservative measure of the volume of Miami cave crayfish habitat lost to sewer line infrastructure.
In order to calculate the quantity of karstic limestone aquifer habitat currently available to each analysis unit of Miami cave crayfish (C), we used the formula:
C = [(Depth of Biscayne Aquifer) x (Surface area of karstic limestone aquifer habitat currently available)] - (Volume of Miami cave crayfish habitat lost to sewer line infrastructure)
In order to calculate the quantity of karstic limestone aquifer habitat that would be available to each analysis unit of Miami cave crayfish in the absence of anthropogenic effects (X), we used the formula:
Exhibit 16
138 X = (Depth of Biscayne Aquifer) x (Surface area of karstic limestone aquifer habitat that would be available in the absence of anthropogenic effects)
Next, we compared these measures to generate a Habitat Quantity factor (HQ) for each analysis unit of the species, using the following formula:
HQ = 100 x (C/X)
The resulting HQ value represents the percentage of habitat that would be available to each Miami cave crayfish analysis unit in the absence of anthropogenic effects, which is actually accessible to the species currently. This measure only assesses the quantity of karstic limestone aquifer habitat and does not evaluate the quality of that habitat. The Habitat Quantity factors for each analysis unit of the species are reported in Table AE.1.
Table AE.1. Habitat Quantity factors for each analysis unit of Miami cave crayfish.
Analysis Unit Percentage of Habitat 1
98 2
98 3
98 4
97 5
93 6
99 7
98 In order to relate these Habitat Quantity factors to resiliency estimates for each analysis unit of the species, we categorized the resulting percentages into high, moderate, and low based on their likelihood to contribute to high population resiliency, moderate population resiliency, or low population resiliency as defined in Table 4.7. These delineations are described in Table AE.2. All analysis units of Miami cave crayfish exhibited high values for this population resiliency factor.
Table AE.2. Relationship between Habitat Quantity values and population resiliency measures.
Population Resiliency Factor High Moderate Low Exhibit 16
139 Quantity of karstic limestone aquifer habitat 80%
50-80%
50%
Habitat Quality - Quality of Surface Cover We evaluated the quality of surface cover throughout the range of each analysis unit of Miami cave crayfish using a global land use/land cover map for the year 2020 developed by Esri (2021).
The layer presents a global map of land use/land cover at 10 m resolution, which was derived from Sentinel-2 imagery as a composite of land use/land cover predictions for ten categories throughout the year such that a representative snapshot of land use/land cover was generated for 2020 overall (Esri 2021). In order to ground truth the land use/land cover delineations provided by the Esri (2021) data for Miami-Dade County, we randomly selected five localities for each category of land use/land cover within the endemic range of Miami cave crayfish and cross-checked the localities with basemap satellite imagery available from Esri via ArcGIS Pro. No Snow/Ice or Cloud classifications were present within the endemic range of the species. All five Flooded Vegetation sites correlated with areas of dry land vegetation, prompting us to check all localities recorded as Flooded Vegetation within Miami cave crayfish range. We subsequently determined that this Esri (2021) classification should be equated to Grass, Trees, or Scrub/Shrub across the region for the purposes of our analyses. All randomly selected localities for the remaining seven categories were confirmed by the satellite imagery.
Next, we sorted each of the ten classifications of land use/land cover in the Esri (2021) layer into high, moderate, and low quality of surface cover based on the definition of surface cover quality in relation to Miami cave crayfish needs. We did not classify Water since these areas do not serve as potential Miami cave crayfish habitat and were removed from the analysis. Areas containing quarrying operations (defined as Extraction, Excavation, Quarrying, Rock-Mining, excluding the resulting water body in the Miami-Dade County land use shapefile (Miami-Dade County 2021a)) were also excluded from the analysis.
Currently, there is no information available regarding the amount of organic carbon contributed by each type of surface cover to the underlying aquifer habitat of Miami cave crayfish nor the depth or horizontal distance to which that organic carbon is distributed once it enters groundwater systems. Accordingly, we are restricted in our estimation of the direct relationship between surface cover and Miami cave crayfish habitat occupancy. However, we can rely on a relative measure of this relationship by evaluating the surface area overlain by each type of land cover across the endemic range of the species. Using ArcGIS, we calculated the total surface area covered by each of the surface quality categories described above. We then used the classifications surface cover quality to adjust each surface area measure to represent the likelihood of current occupancy of the habitat by Miami cave crayfish in relation to the quality of surface cover present: low quality surface area was multiplied by 0.1; moderate quality surface area was multiplied by 0.5; and high quality surface area was multiplied by 1. The resulting Exhibit 16
140 value (CSC) was a relative measure of the habitat currently accessible to Miami cave crayfish based solely on the quality of surface cover present.
Finally, we used these modified values of total surface area to compare the quality of surface cover currently present in the range of each analysis unit of Miami cave crayfish to that which would be present in the absence of any anthropogenic influence. Total surface area of high quality surface cover habitat present in the absence of anthropogenic effects (XSC) was estimated by using the total surface area, minus water, as measured above without any adjustments via modifier multiplications. We compared these values to generate a Habitat Quality factor for Quality of Surface Cover (HSC) for each analysis unit of the species, using the following formula:
HSC = 100 x (CSC/XSC)
The Habitat Quality factors for Quality of Surface Cover for each Miami cave crayfish analysis unit are reported in Table AE.3. In order to relate these Habitat Quality values to resiliency estimates for each analysis unit of the species, we categorized the resulting percentages into high, moderate, and low based on their likelihood to contribute to high population resiliency, moderate population resiliency, or low population resiliency as defined in Table 4.7.
These classifications are described in Table AE.4. All analysis units of Miami cave crayfish exhibited low values for this population resiliency factor.
Table AE.3. Habitat Quality factors for Quality of Surface Cover for each analysis unit of Miami cave crayfish.
Analysis Unit Percentage of Habitat 1
36 2
29 3
32 4
18 5
19 6
13 7
11 Table AE.4. Relationship between Habitat Quality factors for Quality of Surface Cover values and population resiliency measures.
Population Resiliency Factor High Moderate Low Exhibit 16
141 Quality of surface cover 80%
50-80%
50%
Habitat Quality - Freshwater Quality As discussed in section 4.1.3, we approximated the degree of influence of anthropogenic sources of water contamination on Miami cave crayfish by evaluating land use in Miami-Dade County in conjunction with particle transport behavior within the Biscayne aquifer system within ArcGIS.
We employed the same polygon feature class of existing land use within Miami-Dade County (Miami-Dade County 2021a) as was used above for calculating Habitat Quantity factors for each Miami cave crayfish analysis unit. We classified each of the land use types represented in the shapefile as a source or non-source for the five main categories (i.e., pharmaceuticals, pesticides, volatile organic compounds, excess nutrients, and excess trace elements) of anthropogenic water contamination (reviewed in section 3.4). Likely and unlikely sources for anthropogenic water pollutants were delineated based on a review of the following literature: Vincent (1984), Miles and Pfeuffer (1997), Lietz (1999), Bucknor (2002), Garofolo et al. (2002), Bradner et al. (2005),
Harman-Fetcho et al. (2005), Ritter et al. (2007), Carriger and Rand (2008), Munoz-Carpena et al. (2008), Schuler et al. (2008), Pfeuffer (2009), Chen et al. (2010), Briceno et al. (2011),
Gurdak and Qi (2012), Castro et al. (2013), Newman (2015), Marchi et al. (2016), Bargar et al.
(2017), Rice et al. (2017), de Souza et al. (2020), and Ng et al. (2021). If a land use category was defined as a likely source for a non-natural pollutant, the category received a source value of 1.
If a land use category was judged to be an unlikely source for a non-natural pollutant, the category received a source value of 0 (Table AE.5). Total source values were calculated for each land use category in the shapefile by summing up the source values for all five categories of water contaminants. Since the effects of excess nutrients on Miami cave crayfish morbidity and mortality are likely to be significantly less detrimental to populations than are those imparted by pharmaceuticals, pesticides, volatile organic compounds, and excess trace elements (section 3.4),
we adjusted the source value for excess nutrients to 0.25 when calculating the total source value for each land use class (Table AE.5).
Table AE.5. Source values, total source values, and Freshwater Quality values for each category of land use (Miami-Dade County 2021a) within the endemic range of Miami cave crayfish.
Source values are recorded for each of the five main types of non-natural water pollutants that most likely have adverse effects on the morbidity and mortality of Miami cave crayfish as reviewed in section 3.4. VOCs = Volatile Organic Compounds.
Land Use Description Source Values Exhibit 16
142 Pharmaceuticals Pesticides VOCs Excess Nutrients Excess Trace Elements Total Source Value Freshwater Quality Value Beaches.
0 0
0 0
0 0
High Other Nature Preserves and Protected Areas (State Mangrove Preserves, Turkey Point Wilderness Area, Big Cypress Swamp Preserves, and acquired government owned EEL sites).
0 0
0 0
0 0
High Vacant Government owned or controlled.
0 0
0 0
0 0
High Vacant, Protected, Government-Owned or controlled. EEL sites included 0
0 0
0 0
0 High Vacant, Protected, Privately-Owned. Proposed and designated EEL sites until acquired, or protected under any other conservation or environmental mechanism.
0 0
0 0
0 0
High Wellfields.
0 0
0 0
0 0
High Extraction, Excavation, Quarrying, Rock-Mining, excluding the resulting water body (see 917).
0 0
1 0
0 1
Moderate Governmental/Public Administration (Other than Military or Penal).
0 1
0 0
0 1
Moderate Multi-Family, High Density (Over 25 DU/Gross Acre).
0 1
0 1
0 1.25 Moderate Multi-Family, Low-Density (Under 25 DU/Gross Acre).
0 1
0 1
0 1.25 Moderate Nursing homes, Assisted living facilities, and Adult congregate living quarters 0
1 0
1 0
1.25 Moderate Single-Family, Low-Density (Under 2 DU/Gross Acre).
0 1
0 1
0 1.25 Moderate Single-Family, Med.-Density (2-5 DU/Gross Acre).
0 1
0 1
0 1.25 Moderate Townhouses.
0 1
0 1
0 1.25 Moderate Exhibit 16
143 Two-Family (Duplexes).
0 1
0 1
0 1.25 Moderate Communications (Radio, TV, Cable, and Phone), excluding Antenna Arrays.
0 1
1 0
0 2
Moderate Industrial Extensive 0
0 1
0 1
2 Moderate Industrial Intensive, Office type of use 0
1 1
0 0
2 Moderate Major Transmission Lines.
0 1
1 0
0 2
Moderate Penal and Correctional.
0 1
1 0
0 2
Moderate Vacant, Non-Protected, Privately-Owned.
0 1
1 0
0 2
Moderate Colleges and Universities, Including Research Centers, Public and Private.
0 1
1 1
0 2.25 Moderate County Operated Parks.
0 1
1 1
0 2.25 Moderate Cultural (auditoriums, convention centers, exhibition centers, museums, art galleries, libraries).
0 1
1 1
0 2.25 Moderate Hospitals, clinics, medical offices and/or dental facilities 0
1 1
1 0
2.25 Moderate Houses of Worship and Religious, and associated uses (parking, retreat houses, residencies, childcare, etc.).
0 1
1 1
0 2.25 Moderate Industrial intensive, Commercial Condominium type of use 0
1 1
1 0
2.25 Moderate Major Approved Projects.
0 1
1 1
0 2.25 Moderate Mobile Home Parks and Permanent Mobile Homes.
0 1
1 1
0 2.25 Moderate Municipal Operated Parks 0
1 1
1 0
2.25 Moderate Office and/or Business and other services (ground level) /
Residential (upper levels). Low-density < 15 dwellings per acre or 4 floors.
0 1
1 1
0 2.25 Moderate Office Building.
0 1
1 1
0 2.25 Moderate Office/Business/Hotel/Residentia
- l. Substantial components of each use present, Treated as any combination of the mentioned uses with a hotel as part of development.
0 1
1 1
0 2.25 Moderate Private Recreational Camps/Areas not associated with 0
1 1
1 0
2.25 Moderate Exhibit 16
144 private Residential Developments (Boy Scout/Girl Scout Camps, Private Recreational Camps). Includes private tennis courts and pools that are part of the recreational complex.
Private Recreational Facilities Associated with private Residential Developments, except marinas/yacht basins, includes landscape and open spaces associated to residential, commercial and office developments.
0 1
1 1
0 2.25 Moderate Private Schools, Including Playgrounds (K-12, Vocational Ed., Day Care and Child Nurseries).
0 1
1 1
0 2.25 Moderate Public Schools, Including Playgrounds (K-12, Vocational Ed., Day Care and Child Nurseries).
0 1
1 1
0 2.25 Moderate Residential MF-- government-owned or government subsidized multi-family residential or elderly housing 0
1 1
1 0
2.25 Moderate Residential predominantly (condominium/ rental apartments with lower floors Office and/or Retail. High density > 15 dwelling units per ac, multi-story buildings (Generally more than 5 stories).
0 1
1 1
0 2.25 Moderate Residential SF--government-owned or government subsidized multi-family residential or elderly housing 0
1 1
1 0
2.25 Moderate Sales and Services (Wholesale facilities, Spot commercial, strip commercial, neighborhood shopping centers/plazas).
Excludes office facilities.
0 1
1 1
0 2.25 Moderate Shopping Centers (Regional and Community).
0 1
1 1
0 2.25 Moderate Exhibit 16
145 Single-Family, High Density (Over 5 DU/Gross Acre, other than Townhouses, Duplexes and Mobile Homes).
0 1
1 1
0 2.25 Moderate Social Services, and Charitable institutions (Shrines, Elks, Moose, Lions Club).
0 1
1 1
0 2.25 Moderate TRANSIENT-RESIDENTIAL (HOTEL-MOTEL) 0 1
1 1
0 2.25 Moderate Water Supply Plants.
0 1
1 1
0 2.25 Moderate Airports (other than Military and Small Grass Airports).
0 1
1 0
1 3
Low Canal right-of-way.
0 1
1 0
1 3
Low Bus/Truck/Freight Forwarding Terminals.
0 1
1 0
1 3
Low Electric Power (Generator and Substation, and Service Yards).
0 1
1 0
1 3
Low Fallow.
0 1
1 0
1 3
Low Industrial Intensive, heavy-light manufacturing, and warehousing-storage type of use 0
1 1
0 1
3 Low Marina complexes (docks, piers, moorings, ramps, boat lifts and hoists, boat maintenance and repair, boat storage, fueling operations) for recreational craft located within Parks and Preserves and other small craft harbor complexes used primarily for rec 0
1 1
0 1
3 Low Marine commercial (includes private commercial [non-recreational] marinas and repair yards on public or private land).
0 1
1 0
1 3
Low Oil and Gas Storage (Tank Farms).
0 1
1 0
1 3
Low Parking - Public and Private Garages and Lots.
0 1
1 0
1 3
Low Paved Highways, Expressways and Ramps.
0 1
1 0
1 3
Low Private Drives.
0 1
1 0
1 3
Low Railroads - Terminals, Trackage, and Yards.
0 1
1 0
1 3
Low Road Maintenance and Storage Yards, and Motor Pools.
0 1
1 0
1 3
Low Exhibit 16
146 Small Grass Airports (Includes Crop Dusting Activities).
0 1
1 0
1 3
Low Street right-of-way and entrance features both public and private, and utility easements.
0 1
1 0
1 3
Low Streets and Roads, except Expressways and Private Drives.
0 1
1 0
1 3
Low Agriculture, Other (Exotic Birds, Monkeys, Research Facilities).
1 1
0 1
1 3.25 Low Antenna Arrays.
0 1
1 1
1 3.25 Low Cemeteries.
0 1
1 1
1 3.25 Low Farm Storage Areas (Storage Structures or Lots for Farm Implements).
0 1
1 1
1 3.25 Low Fish Farms (Includes Tropical Fish Aquariums, Fish and Alligator Farms).
1 1
0 1
1 3.25 Low Golf courses, Public and Private.
0 1
1 1
1 3.25 Low Groves.
0 1
1 1
1 3.25 Low Highways and Expressways right-of-way and associated open and landscaped areas excluding paved expressways and ramps.
0 1
1 1
1 3.25 Low Horse Training and Stables.
1 1
0 1
1 3.25 Low Junk Yard.
0 1
1 1
1 3.25 Low Military Facilities.
0 1
1 1
1 3.25 Low Plant Nurseries (Includes Sod Farms and Ornamental Nurseries).
0 1
1 1
1 3.25 Low Poultry.
1 1
0 1
1 3.25 Low Recreational Vehicle Parks/Camps.
0 1
1 1
1 3.25 Low Row and Field Cropland.
0 1
1 1
1 3.25 Low Sports Stadiums, Arenas, and Tracks.
0 1
1 1
1 3.25 Low Coastal Water (Bay only) within the Biscayne Bay Urban Aquatic Preserve (Excluding Ocean Waters).
1 1
1 1
1 4.25 Low Inland water bodies (Lakes, Ponds, and Watercourses) associated with industrial areas, industrial parks and new industrial development.
1 1
1 1
1 4.25 Low Exhibit 16
147 Inland water bodies (Lakes, Rock Pits) associated with extraction, excavation, quarrying and rock-mining activities.
1 1
1 1
1 4.25 Low Inland water bodies (Lakes, Watercourses) associated with residential developments.
1 1
1 1
1 4.25 Low Other inland water bodies (Lakes, Ponds, Watercourses other than rivers and canals),
including road borrow pits.
1 1
1 1
1 4.25 Low Pasture (Grazing, Animal Farming, Dairy Farms and Animal Feed Lots), excluding Horse and Poultry.
1 1
1 1
1 4.25 Low Remaining Bay Waters (Excluding Ocean).
1 1
1 1
1 4.25 Low Rivers and Canals. (Water) 1 1
1 1
1 4.25 Low Sewerage Treatment Plants.
1 1
1 1
1 4.25 Low Solid Waste Disposal and Transfer (Includes Dumps, Solid Waste Land Fills, Resource Recovery Plants and Facilities, Trash Transfer Stations).
1 1
1 1
1 4.25 Low Septic tanks are significant sources of both pharmaceuticals and excess nutrients to the Biscayne Aquifer system (Bradner et al. 2005, pp. 3, 10; Chen et al. 2010, pp. 878, 879; Ng et al. 2021, entire). We assessed the contribution of anthropogenic pollutants from septic tank systems to Miami cave crayfish habitats by analyzing a point feature class of Onsite Sewage Treatment and Disposal Systems within Miami-Dade County as reported by the Florida Department of Health (Miami-Dade County 2021b). On July 22, 2021, we downloaded the shapefile, which had been last updated on July 21, 2021, into ArcGIS. All septic tanks were assigned a total source value of 1.25 (1 for pharmaceutical and 0.25 for excess nutrients).
Based on the total source values assigned to septic tank systems and each land use category, we classified these features into high, moderate, and low quality of freshwater in alignment with the definition of freshwater quality outlined in the subsection Sufficient Water Quality within section 2.7 (Table AE.5). Total source values between 0 and 0.25 were assigned a high freshwater quality value, while those between 1 and 2.25 were assigned a moderate freshwater quality value (1-2.25) and those between 3 and 4.25 were assigned a low freshwater quality value (Table AE.5). Since water pollutants are more likely to interact synergistically than Exhibit 16
148 additively in their adverse impact on Miami cave crayfish individuals, these classifications likely underrepresent the actual negative effects of multiple contaminants on populations of the species across their endemic range.
Since the Biscayne Aquifer is a mobile flow system (section 2.5.3), anthropogenic toxicants are transported throughout the aquifer system after entry from point sources of contamination.
Consequently, the impact of non-natural water contamination on Miami cave crayfish is dispersed beyond the boundaries of the septic tank locations and land use boundaries that we classified above. In order to estimate the extension of freshwater contamination into the aquifer system, we applied estimates for particle transportation distances through the Biscayne Aquifer below the Atlantic Coastal Ridge (Harvey et al. 2008, entire; Shapiro et al. 2008, entire) to calculate buffers around each septic tank and land use type. After extensive field and laboratory studies (Harvey et al. 2008, entire; Shapiro et al. 2008, entire), Harvey et al. (2008, p. 10) concluded that a minimum distance of 328.1 ft (100 m) was necessary for a more than one factor of ten removal of 3 to 5 m -sized particles entering the karstic limestone of the Biscayne Aquifer underlying the Atlantic Coastal Ridge. In addition, some degree of filtering of surface-sourced pollutants is likely to occur during transport through intermediate layers of surface cover and non-aquifer-bearing limestone deposits prior to deposition within the underlying Biscayne Aquifer system (section 3.4). Accordingly, we placed conservative buffers of 984.3 ft (300 m) around each septic tank location and each land use category in the land use shapefile except Inland water bodies (all classifications) and Rivers and canals. Since there is more direct transmission of chemical toxicants between the groundwater within the Biscayne Aquifer and adjacent surface waters of rivers, canals, and inland water bodies (section 3.4), particle transport is likely to occur over longer distances for contaminants entering the aquifers from large water bodies. For this reason, we applied buffers of 1,968.5 ft (600 m) to the land use categories of Inland water bodies (all classifications) and Rivers and canals within the land use shapefile.
Using ArcGIS, we merged all of the buffered land use features and septic tank locations. Land use areas that could not serve directly as habitat for Miami cave crayfish (i.e., Coastal Waters (all classifications); Inland water bodies (all classifications); Remaining bay waters; Remaining ocean waters; Rivers and canals; and Extraction, Excavation, Quarrying, Rock-Mining, excluding the resulting water body) were removed from analysis but their buffers were retained.
Areas of overlap that included features with low freshwater quality were classified as low freshwater quality. We recalculated total source values for all areas of overlap between moderate and/or high freshwater quality designations and reclassified these regions in accordance with their updated total source values. Areas that shared no overlap with other buffered features retained their original categorization of freshwater quality. Next, we calculated the total surface area covered by each of these freshwater quality categories and adjusted the total surface area measures via multipliers related to these freshwater quality values: low quality freshwater area was multiplied by 0.1; moderate quality freshwater area was multiplied by 0.5; and high quality freshwater area was multiplied by 1. The resulting value (CFQ) was a relative Exhibit 16
149 measure of the habitat currently accessible to Miami cave crayfish based solely on the degree of anthropogenic contamination of freshwater within the species aquifer habitat.
Finally, we used these modified values of total surface area to compare the freshwater quality currently present in the range of each analysis unit of Miami cave crayfish to that which would be present in the absence of any anthropogenic influence. We estimated the surface area overlying Miami cave crayfish habitat that would be devoid of non-natural freshwater contamination in the absence of human activity (XFQ) by performing the total area calculations described in the previous section for CFQ and treating all surface area as high quality freshwater regions. We compared these values to generate a Habitat Quality factor for Freshwater Quality related to anthropogenic water contamination (HFQ) for each analysis unit of the species, using the following formula:
HFQ = 100 x (CFQ/XFQ)
The Habitat Quality factors for Freshwater Quality for each Miami cave crayfish analysis unit are reported in Table AE.6. In order to relate these Habitat Quality values to resiliency estimates for each analysis unit of the species, we categorized the resulting percentages into high, moderate, and low based on their likelihood to contribute to high population resiliency, moderate population resiliency, or low population resiliency as defined in Table 4.7. These classifications are described in Table AE.7. All analysis units of Miami cave crayfish exhibited low values for this population resiliency factor.
Table AE.6. Habitat Quality factors for Freshwater Quality related to anthropogenic water contamination for each analysis unit of Miami cave crayfish.
Analysis Unit Percentage of Habitat 1
10 2
11 3
10 4
11 5
10 6
10 7
10 Table AE.7. Relationship between Habitat Quality values for Freshwater Quality related to anthropogenic water contamination and population resiliency measures.
Population Resiliency Factor High Moderate Low Exhibit 16
150 Freshwater Quality (Anthropogenic Contamination Measure) 80%
50-80%
50%
Habitat Quality - Freshwater Availability As described in section 4.1.4, we used a relative measure to evaluate the influence of saltwater intrusion on Miami cave crayfish habitat occupancy. The most recent estimate of the inland extent of saltwater intrusion within the Biscayne Aquifer on the Atlantic Coastal Ridge is provided by Prinos (2019, entire) for 2018. We duplicated the line of saltwater interface within the Biscayne Aquifer per Prinos (2019, entire) within ArcGIS. Next, we calculated the total surface area of available habitat that overlapped the mapped region of saltwater intrusion for each Miami cave crayfish analysis unit. As in the above analyses, we removed from our calculations any land use categories that represent the absence of Miami cave crayfish habitat (i.e., Coastal Waters (all classifications]); Inland water bodies (all classifications); Remaining bay waters; Remaining ocean waters; Rivers and canals; and Extraction, Excavation, Quarrying, Rock-Mining, excluding the resulting water body).
It was not possible for us to compare current saltwater intrusion into Miami cave crayfish habitat with estimated values for the extent of saltwater intrusion that would exist without anthropogenic effects (section 4.1.4) as we did for the above comparative analyses. Therefore, for each analysis unit, we calculated the percent of the total surface area of currently-available Miami cave crayfish habitat that overlaid saltwater intrusion in 2018 to generate a Habitat Quality factor for Freshwater Availability related to saltwater intrusion (HFA):
HFA = 100 x ([Total surface area overlapping saltwater intrusion 2018]/[Total surface area])
The Habitat Quality factors for Freshwater Availability for each Miami cave crayfish analysis unit are reported in Table AE.8. In order to relate these Habitat Quality values to resiliency estimates for each analysis unit of the species, we categorized the resulting percentages into high, moderate, and low based on their likelihood to contribute to high population resiliency, moderate population resiliency, or low population resiliency as defined in Table 4.7.
These classifications are described in Table AE.9. Analysis units 5 and 7 exhibited low values for this population resiliency factor, while analysis unit 6 exhibited a moderate value and analysis units 1, 2, 3, and 4 exhibited high values.
Table AE.8. Habitat Quality factors for Freshwater Availability related to saltwater intrusion for each analysis unit of Miami cave crayfish.
Exhibit 16
151 Analysis Unit Percentage of Habitat 1
5 2
17 3
19 4
0 5
77 6
26 7
51 Table AE.9. Relationship between Habitat Quality values for Freshwater Availability related to saltwater intrusion and population resiliency measures.
Population Resiliency Factor High Moderate Low Freshwater Availability (Saltwater Intrusion Measure) 20%
20-50%
50%
Habitat Availability - Combining Habitat Quantity and Quality Measures In order to summarize the overall resiliency of Miami cave crayfish, we combined the measures of Habitat Quantity, Quality of Surface Cover, Freshwater Quality, and Freshwater Availability.
First, we generated a Habitat Quality factor for each analysis unit by combining the resiliency measures for Quality of Surface Cover, Freshwater Quality, and Freshwater Availability. Since the factors Freshwater Quality (Anthropogenic Contamination Measure) and Freshwater Availability (Saltwater Intrusion Measure) both relate to overall freshwater quality within Miami cave crayfish habitat, the Combined Habitat Quality Factor was calculated by first combining these two measures to get an overall Freshwater Quality measure. This overall Freshwater Quality measure was then combined with the Quality of Surface Cover measure to calculate the Combined Habitat Quality Factor. In order to remain conservative in our valuation of each combined habitat factor, for each pairwise combination: 1. when Low + Moderate, the resulting combined value was determined to be Low, and 2. when High + Moderate, the resulting combined value was determined to be Moderate. See Figure AE.1 for an example calculation of the Combined Habitat Quality Factor for analysis unit 1.
Analysis Unit Habitat Quality Factors Quality of Surface Cover Freshwater Quality (Anthropogenic Contamination Measure)
Freshwater Availability (Saltwater Intrusion Measure)
Combined Habitat Quality Factor 1
Low Low
+
High Exhibit 16
152 Low
+
Moderate Low Low Figure AE.1. Combined Habitat Quality Factor calculation for Miami cave crayfish analysis unit
- 1. The measure is determined by combining the three habitat quality elements (Quality of Surface Cover, Freshwater Quality [Anthropogenic Contamination Measure], and Freshwater Availability [Saltwater Intrusion Measure]). For analysis unit 1, the overall Combined Habitat Quality Factor was calculated by first combining the Low Freshwater Quality (Anthropogenic Contamination Measure) with the High Freshwater Availability (Saltwater Intrusion Measure) to get Moderate. When this Moderate was then combined with the Low Quality of Surface Cover, the Low rank outweighed the Moderate rank to get an overall Combined Habitat Quality Factor of Low.
We determined that quality of available habitat was a stronger driver of Miami cave crayfish habitat occupancy than was quantity of available habitat. Therefore, we weighted Combined Habitat Quality factors two times higher than Habitat Quantity factors when estimating the overall Combined Habitat Factor values for Miami cave crayfish analysis units. Accordingly, the overall Combined Habitat Factor for each analysis unit consisted of two low rankings (Combined Habitat Quality factors) and one high ranking (Habitat Quantity factor) such that the low rankings outweighed the high ranking and resulted in an overall Combined Habitat Factor value of low for all seven Miami cave crayfish analysis units (Table 4.8). In order to relate these overall Combined Habitat Factor values to resiliency estimates for each analysis unit of the species, we equated the low values with low population resiliency as defined in Table 4.7. Consequently, the current resiliency of Miami cave crayfish across all seven analysis units was determined to be low (Figure 4.2).
Exhibit 16