ML070170228

VYNPS - SEIS Web Reference - Dwarf Wedge Mussel Recovery Plan

ML070170228
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Issue date:	02/08/1993
From:	Moser G US Dept of Interior, Fish & Wildlife Service
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DWARF WEDGE MUSSEL (Alasmidonta heterodon)

RECOVERY PLAN U.S. Fish and Wildlife Service, Northeast Region

DWARF WEDGE MUSSEL (Alasmidonta heterodon)

RECOVERY PLAN Prepared by:

G. Andrew Moser Annapolis Field Office U.S. Fish and Wildlife Service Annapolis, Maryland for Region Five U.S. Fish and Wildlife Service Hadley, Massachusetts Approved:

FEB08 ~i993 Date:

EXECUTIVE

SUMMARY

OF THE DWARF WEDGE MUSSEL RECOVERY PLAN CURRENT STATUS: This freshwater mussel has declined precipitously over the last hundred years. Once known from at least 70 locations in 15 major Atlantic slope drainages from New Brunswick to North Carolina, it is now known from only 20 localities in eight drainages. These localities are in New Hampshire, Vermont, Connecticut, New York, Maryland, Virginia, and North Carolina. The dwarf wedge mussel (Alasmidonta heterodon) was listed as an endangered species in March of 1990.

HABITAT REQUIREMENTS AND LIMITING FACTORS: The dwarf wedge mussel lives on muddy sand, sand, and gravel bottoms in creeks and rivers of various sizes. It requires areas of slow to moderate current, good water quality, and little silt deposition. The species recent dramatic decline, as well as the small size and extent of most of its remaining populations, indicate that individual populations remain highly vulnerable to extirpation.

RECOVERY OBJECTIVES: (1) Dowulist to threatened status, and (2) delist.

RECOVERY CRITERIA To downlist, populations of A. heterodon in the mainstem Connecticut River, Ashuelot River, Neversi.nk River, upper Tar River, three sites in the Neuse River system, as well as in at least six other rivers, must be viable based on monitoring results over a 10-15 year period. To delist, populations must be dispersed widely enough within at least 10 of these rivers such that a single event is unlikely to eliminate a population from a given river reach. These populations must be distributed throughout the species range, and must be permanently protected from foreseeable threats.

ACTIONS NEEDED:

1. Collect basic data needed for protection of A. heterodon populations.

2. PreserveA. heterodon populations and occupied habitats.

3. Develop an education program.

4. Conduct life history studies and identify ecological requirements of the species.

5. If feasible, re-establish populations within the species historical range.

6. Implement a program to monitor population levels and habitat conditions.

7. Periodically evaluate the recovery program.

ESTIMATED COSTS (SlOOGs):

Year Need 1

~

~

IQL~

FYi 82 31 35 148 FY2 107 65 6

30 208 FY3 iCJ7 75 11 193 FY4 55 45 1

101 FY5 45 1

15 30 91 FY6 45 1

15 61 FY7 15 1

15 31 FY8 15 1

15 30 61 FY9 15 1

15 31 FY10

..li..

..L

.~Q....

..AL Total 351 366 24 35 75 120 971

• Total costs to provide long-term protection of essential habitats (Need 2) are not yet known.

• • No costs are associated with Need 7.

DATE OF RECOVERY: Because a period of at least 10 years is required to document the stability of dwarf wedge mussel populations, downlisting will be considered sometime after the year 2002, when the recovery criterion has been met.

Recovery plans delineate reasonable actions needed to recover and/or protect listed species.

Attainment of recovery objectives and availability of funds are subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities.

Recovery plans do not necessarily represent the views or official position of any individuals or agencies involved in plan formulation, other than the U* S. Fish and Wildlife Service.

Approved recovery plans may be modified as dicatated by new findings, changes in species status, and the completion of recovery tasks.

Literature citations for this plan should read as follows:

U.S. Fish and Wildlife Service.

1993.

Dwarf Wedge Mussel (Alasmidonta heterodon)

Recovery Plan.

Hadley, Massachusetts. 52 pp.

Copies of this plan can be purchased from:

Fish and Wildlife Reference Service 5430 Grosvenor Lane, Suite 110 Bethesda1 Maryland 20814 3014 :640:

or 18005823421 Fees vary according to number of pages.

DWARF WEDGE MUSSEL (Alasmidonta heterodon)

RECOVERY PLAN U.S. Fish and Wildlife Service, Northeast Region

DWARF WEDGE MUSSEL (Alasmidonta heterodon)

RECOVERY PLAN Prepared by:

G. Andrew Moser Annapolis Field Office U.S. Fish and Wildlife Service Annapolis, Maryland for Region Five U.S. Fish and Wildlife Service Hadley, Massachusetts Approved:

FEB08 ~i993 Date:

EXECUTIVE

SUMMARY

OF THE DWARF WEDGE MUSSEL RECOVERY PLAN CURRENT STATUS: This freshwater mussel has declined precipitously over the last hundred years. Once known from at least 70 locations in 15 major Atlantic slope drainages from New Brunswick to North Carolina, it is now known from only 20 localities in eight drainages. These localities are in New Hampshire, Vermont, Connecticut, New York, Maryland, Virginia, and North Carolina. The dwarf wedge mussel (Alasmidonta heterodon) was listed as an endangered species in March of 1990.

HABITAT REQUIREMENTS AND LIMITING FACTORS: The dwarf wedge mussel lives on muddy sand, sand, and gravel bottoms in creeks and rivers of various sizes. It requires areas of slow to moderate current, good water quality, and little silt deposition. The species recent dramatic decline, as well as the small size and extent of most of its remaining populations, indicate that individual populations remain highly vulnerable to extirpation.

RECOVERY OBJECTIVES: (1) Dowulist to threatened status, and (2) delist.

RECOVERY CRITERIA To downlist, populations of A. heterodon in the mainstem Connecticut River, Ashuelot River, Neversi.nk River, upper Tar River, three sites in the Neuse River system, as well as in at least six other rivers, must be viable based on monitoring results over a 10-15 year period. To delist, populations must be dispersed widely enough within at least 10 of these rivers such that a single event is unlikely to eliminate a population from a given river reach. These populations must be distributed throughout the species range, and must be permanently protected from foreseeable threats.

ACTIONS NEEDED:

1. Collect basic data needed for protection of A. heterodon populations.

2. PreserveA. heterodon populations and occupied habitats.

3. Develop an education program.

4. Conduct life history studies and identify ecological requirements of the species.

5. If feasible, re-establish populations within the species historical range.

6. Implement a program to monitor population levels and habitat conditions.

7. Periodically evaluate the recovery program.

ESTIMATED COSTS (SlOOGs):

Year Need 1

~

~

IQL~

FYi 82 31 35 148 FY2 107 65 6

30 208 FY3 iCJ7 75 11 193 FY4 55 45 1

101 FY5 45 1

15 30 91 FY6 45 1

15 61 FY7 15 1

15 31 FY8 15 1

15 30 61 FY9 15 1

15 31 FY10

..li..

..L

.~Q....

..AL Total 351 366 24 35 75 120 971

• Total costs to provide long-term protection of essential habitats (Need 2) are not yet known.

• • No costs are associated with Need 7.

DATE OF RECOVERY: Because a period of at least 10 years is required to document the stability of dwarf wedge mussel populations, downlisting will be considered sometime after the year 2002, when the recovery criterion has been met.

Recovery plans delineate reasonable actions needed to recover and/or protect listed species.

Attainment of recovery objectives and availability of funds are subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities.

Recovery plans do not necessarily represent the views or official position of any individuals or agencies involved in plan formulation, other than the U* S. Fish and Wildlife Service.

Approved recovery plans may be modified as dicatated by new findings, changes in species status, and the completion of recovery tasks.

Literature citations for this plan should read as follows:

U.S. Fish and Wildlife Service.

1993.

Dwarf Wedge Mussel (Alasmidonta heterodon)

Recovery Plan.

Hadley, Massachusetts. 52 pp.

Copies of this plan can be purchased from:

Fish and Wildlife Reference Service 5430 Grosvenor Lane, Suite 110 Bethesda1 Maryland 20814 3014 :640:

or 18005823421 Fees vary according to number of pages.

TABLE OF CONTENTS PARrI:

INTROIXICrION Description Life History and Ecology Distribution Reasons for Decline and Threats to Continued Existence PARI II:

RECOVERY Recovery Goal and Objectives RecoveryTasks LiteratureCited PART III:

fl4PLEMENTATION SCHEI~JLE APPENDIX:

LIST OF REVIEWERS 1

1 3

6 11 23 23 24 37 41 FIGURES ~ND TABLES Figure 1.

Figure 2.

Figui~- 3.

Figure 4.

Typical life cycle of a freshwater mussel Partially exposed Alasmidonta heterodon siphoning G]ochidia of Alasmidonta heterodon Distribution of Alasmidonta heterodon Historical and present occurrences of the dwarf wedge mussel Comparative toxicities of selected metals in soft water to several invertebrates and fish Status of dwarf wedge mussel populations Stepdownrecoveryoutline 4

5 5

8 Table 1.

Table 2.

Table 3.

Table 4.

9 17 20 34

PART I: INTRODUCTION The dwarf wedge mussel (Alasmidonta heterodon) was listed as an endangered species on March 14, 1990 (55 FR 9447).

This freshwater mussel has declined precipitously in the past hundred years (Master 1986).

Always a rare species confined to Atlantic slope drainages from North Carolina to New Brunswick, the dwarf wedge mussel has been recorded in approximately 70 localities in 15 major drainages since the species discovery in the early 1800s.

It is now thought to have been extirpated from all but 20 localities.

The 20 known remaining populations, with one exception, are thought to be relatively small and to be declining as a result of continued environmental assaults in the form of agricultural, industrial, commercial, and domestic pollution/runoff.

Channelization, removal of shoreline vegetation, development, and road and dam construction also threaten some populations.

DESCRIPTION The dwarf wedge mussel was first described by Lea (1829) as Unio heterodon.

It was subsequently placed in the genus Alasmidonta by Simpson (1914).

Due to its unique soft-tissue anatomy and conchology, Oztnann (1914) placed it in a monotypic subgenus Prolasmidonta.

Fuller (1977) believed the antiquity and unique shell characters of Prolasmidonta were sufficient for elevation to full generic rank and named the species Prolasmidonta heterodon.

Clarke 1

(198la) retained the genus name Alasmidonta and considered Prolasmidonta to be a subjective synonym of the subgenus Pressodonta Simpson 1900.

The species name, heterodon, refers to the chief distinguishing characteristic of this species, which is the only North American freshwater mussel that consistently has two lateral teeth on the right valve, but only one on the left (Fuller 1977).

It is a small mussel whose shell rarely exceeds 1.5 inches (38 mm) in length.

The largest specimen ever recorded was 56.5 mm long, taken from the Ashuelot river in New Hampshire (Clarke 1981a).

Clarke (1981a) describes the species as follows:

Shell up to about 45 nun long, 25 mm high, 16 nun wide, and with shell wall about 1 mm thick in mid-anterior region; more or less ovate or trapezoidal, roundly pointed posterio-basally, thin but not unduly fragile, with rounded posterior

ridge, and of medium inflation.

Females more inflated posteriorly than males.

Sculpturing absent except for lines of growth and beak sculpture.

Periostracum [outerlayer of shell] brown or yellowish brown, and with greenish rays in young or pale-coloured specimens.

Nacre bluish or silvery white, and iridescent posteriorly.

Beak sculpture composed of about 4 curved ridges, which are angular on the posterior slope.

Hinge teeth small but distinct; pseudo-cardinal teeth compressed, 1 or 2 in the right valve and 2 in the left; lateral teeth gently curved and reversed, that is, in most L~j?vflTtens, 2 in the right valve and 1 in the left.

Because atypical lateral dentition can occur in this species and others, the lateral tooth configuration should not be used alone to distinguish the species.

The dwarf wedge mussel is likely to be confused only with young members of the genus Ellktio, from which it can be distinguished by its mottled but colorful mantle margin (Fuller 1977).

2

LIFE HISTORY AND ECOLOGY The dwarf wedge mussel lives on muddy sand,

sand, and gravel bottoms in creeks and rivers of varying sizes, in areas of slow to moderate current and little silt deposition.

In the southern portion of its

range, it is often concentrated in areas along logs or in root mats.

In the upper Connecticut River system in New Hampshire, it occurs in shallow water (generally less than onemeter depth during low water) with a firm substrate of sandy mud and gravel, scattered patches of wild celery (Valisneria j~iri~n~J, and little silt deposition (Master 1986).

The most commonly associated freshwater mussels are Ell iptio comDlanata and Alasmidonta undulata.

Other mussels co-occurring throughout the species range include Alasmidonta varicosa StroDhitus undulatus, Anodonta cataracta, Anodonta imbecil is Anodonta imDlicata, ElliDtio lanceolata, ElliDtio fisheriana ElliDtio icterina, Villosa constricta, Villosa delumbus, Lam~silis radiata, Lamosilis cariosa, Lasmiciona subviridis, and LeDtodea ochracea Little is known about the reproductive biology of the dwarf wedge mussel; however, the reproductive biology of freshwater mussels appears to be similar among nearly all species (Figure 1).

During the spawning period, males discharge sperm into the water column, and the sperm are taken in by females during siphoning (Figure 2).

Eggs are fertilized in the suprabranchial cavity or gills, which also serve as marsupia for larval development to mature glochidia.

A.

heteroctori glochidia (Figure

3) are roughly triangular, with hooks, and measure about 0.30 mm in length and 0

• 25 nun in height (Clarke 1981a).

Clarke (1981b) indicates that the dwarf wedge mussel is a long-term brooder.

In longterm brooders, fertilization typically occurs in mid-summer and fall, and glochidia are released the following spring and sununer.

Glochidial release for some long-term brooders also has been observed during fall and winter (Zale 1980).

D. Michaelson (Virginia Polytechnic Institute and State University, 3

Figure 1.

Typical life cycle of a freslivater uusuel 0I 0

Juvenile 9

4

4 Figure 2.

Partially exposed ~lasmidonta heterodon, siphoning Photo coune.ry ofDoug Smith, University of Massachusetts, Amherst Figure 3.

Glochidia of Alasmidozita heterodon Photo couilesy Smithsonian Institution Press, from CIwke (19&Sa) 5

pers.

corn.)

has indicated that the periods of gravidity and glochidial release are highly variable; much of this variation appears to be based on latitude.

Upon release into the water column, mature glochidia of the genus Alasmidonta attach to the fins and soft tissue of the buccal cavity of appropriate host fishes to encyst and eventually metamorphose to the juvenile stage.

When metamorphosis is complete, they drop to the streambed as juvenile mussels.

The host fish (es) for A. heterodon have not been determined.

Studies are currently underway at the Cooperative Fishery and Wildlife Unit of the Virginia Polytechnic Institute and State University (VPI&SU) to determine this and other life history requirements.

DISTRIBUTION Historically, the dwarf wedge mussel was widely but discontinuously distributed in Atlantic drainages from the Petitcodiac River in New Brunswick, Canada, south to the Neuse River in North Carolina.

The species was known from at least 70 locations in 11 states and one Canadian province.

Master (1986) reported that an extensive status survey of historical and potential sites turned up only eight extant populations.

Since

then, 12 additional extant populations have been found in Maryland, Nort~ ~aro1+/-na,Virginia, and New York.

Although a few additional populations may still be discovered, a clear pattern has emerged

relatively small, scattered relict populations remain from a once extensive distribution.

The Neversink River population in New York, estimated at 80,000 mussels, appears to be the sole exception to this pattern; it far outnumbers any other population, although it occupies a relatively short reach of the river.

Figure 4 and Table 1 describe current and historical localities for the dwarf wedge mussel.

The locations of the 20 extant populations are as follows:

6

= Present occurrence 0 = Historical occurrence, presumed extirpated Figure

4. Distribution of Alasmidonta heterodon (insert shows locations in New Brunswick) 8

Connecticut River Drainaae 1.

Connecticut River from the confluence with the Ottauquechee River to Weathersfield Bow in Sullivan

County, New Hampshire and Windsor County, Vermont 2.

Ashuelot River in Cheshire County, New Hampshire 3.

Muddy Brook in Hartford County, Connecticut Delaware River Drainaae 4.

Neversink River in Orange County, New York Tuckahoe Creek (ChoDtank River) DrainaQe 5.

Norwich Creek in Queen Anne s and Talbot Counties, Maryland 6.

Long Marsh Ditch in Queen Anne s and Caroline Counties, Maryland Potomac River Drainaae 7.

McIntosh Run in St. Marys County, Maryland 8.

Nanjemoy Creek in Charles County, Maryland 9.

Aquia Creek in Stafford County, Virginia York River Drainaae 10.

South Anna River in Louisa County, Virginia Nottowav River Drainaae 11.

Nottoway River in Nottoway and Lunenberg Counties, Virginia Tar River Drainacre 12.

Tar River in Granville County, North Carolina 13.

Cedar Creek in Franklin County, North Carolina 14.

Crooked Creek in Franklin County, North Carolina 15.

Stony Creek in Nash County, North Carolina Neuse River Drainacre 16.

Little River in Johnston and Wake Counties, North Carolina 17.

Swift Creek in Johnston County, North Carolina 18.

Middle Creek in Johnston County, North Carolina 19.

Turkey Creek in Wilson and Nash Counties, North Carolina 20.

Moccasin Creek in Nash, Wilson, and Johnston Counties, North Carolina Of these populations, those located in the Connecticut River, the Neversink River, and the Upper Tar River appear to be the largest.

7

Table 1.

Historical (H) and present CP) occurrences of the dwarf wedge mussel P~t;t~Ai2i-River ~u~t,m N~w a

unw~...

IJI UU3Y,*t.Jt.

tana.aa North River NW of Salisbury Petitcodiac River at River Glade Westmoreland County, NB Westmoreland County, NB Merrimack River System Merrimack River at Andover Essex County, MA Taunton River System Canoe river near Norton Bristol County, MA A~awam River System Agawam River Plymouth County, MA Connecticut River System Connecticut River at Bloomfield Connecticut River at Northumberland Connecticut River at Ryegate

-Connecticut River N of Monroe Connecticut River from confluence with the Ottauquechee River to Weathersfield Bow Ashuelot River near Keene Connecticut River at Northfield Connecticut River at Sunderland Connecticut River at Cbicopee Canal at Westfield Connecticut River at Springfield Scantic River near Hampden Fort River in Amherst Mill River at Northampton Connecticut River at Hadley Connecticut River at Granby Philo Brook at Suffield Muddy Brook Essex County, VT Coos County, NH Caledonia County, VT Grafton County, NH Sullivan County, NH and Windsor County, VT Cheshire County, NH Franklin County, MA Franklin County, MA Hampden County, MA Hampden County, MA Hampden County, MA Hampden County, MA Hampshire County, MA Hampshire County, MA Hampshire County, MA Hartford County, CT Hartford County, CT Hartford County, CT Quinniniac River System Ten Mile River at Mixville Quinnipiac River at Meriden Wilmot Brook at New Haven New Haven County, CT New Haven County, CT New Haven County, CT Hackensack River System Brook flowing W from Closter to Hackensack Bergen County, NJ Delaware River System Neversink River Delaware River at Shawnee Princess Creek at Kunideton Pohopoco Creek near Leighton Delaware River Orange County, NY Monroe County, PA Monroe County, PA Carbon County, PA Bucks County, PA (H) 1953 (H) 1960 (H)

(H) 1969 (H)

(H)

(H)

(H)

(H)

(P)

(P)

(H) 1948 (H) 1979 (H)

(H) 1940 (H)

(H) 1951 (H) 1984 (H) 1973 (H)

(H)

(H) 1959 (P)

(H)

(H)

(H)

(H)

(P)

(H) 1919 (H) 1919 (H)

(H) 9

Table 1.

(continued)

Historical (H) and present (P) occurrences of the dwarf wedge mussel Delaware River S~tem (continued

)

Big Neshaminy Creek near Edderson Schuykill River at junction with Darby Creek Canal along Schuykill at Manayunk Schuykill River below Fairmount Dam Bucks County, PA Delaware County, PA Philadelphia County, PA Philadelphia County, PA Susauehanna River S~tem Susquehanna River at Columbia Lancaster County, PA Chootank River S~tem Norwich Creek Long Marsh Ditch Queen Annes and Talbot Cos., MD Queen Annes and Caroline Cos., MD Potomac River System Potomac River near Washington, D.C.

McIntosh Run Nanjemoy Creek Aquia Creek Washington, D.C.

St. Marys County, MD Charles County, MD Stafford County, VA Ratn,ahannock River S~tem Mountain Run Marsh Run near Remington Blue River Culpeper County, VA Fauquier County, VA Orange County, VA York River System South Anna River South Anna River Louisa County, VA Hanover County, VA James River S~tem Maury River (North River) at Lexington Rockbridge County, VA Nottowav River S~tem Nottoway River Nottowaj and Lunenberg Cos., VA Tar River S~tem Tar River Cedar Creek Crooked Creek Stony Creek Granville County, NC Franklin County, NC Franklin County, NC Nash County, NC Neuse River System Neuse River at Poolec Bridge Neuse River E of Raleigh Neuse River NE of Wendell Little River Swift Creek Middle Creek Turkey Creek Moccasin Creek Wake County, NC Wake County, NC Wake County, NC Johnston and Wake Cos., NC Johnston County, NC Johnston County, NC Wilson and Nash Cos., NC Nash, Wilson, and Johnston Cos., NC (H)

(H)

(H) 1919 (H) 1919 (H)

(P)

(P)

(H)

(P)

(P)

(P)

(H)

(H)

(H)

(P)

(H)

(H)

(P)

(P)

(P)

(P)

(P)

(H)

(H)

(H)

(P)

(P)

(P)

(P)

(P) 10

REASONS FOR DECLINE AND THREATS TO CONTINUED EXISTENCE Although the dwarf wedge mussel still survives at a number of sites, its dramatic decline as well as the small size and extent of most of its remaining populations indicate that it is highly vulnerable to extirpation.

Evidence is growing that the decline of Alasmidonta heterodon may be the forerunner of a general decline in the Unionid fauna of the Atlantic slope drainages.

For example, recent status surveys indicate that other formerly widespread mussel species, including Alasmidonta varicosa and L~z~+/-1i&iu~yiri~ii, are also declining.

This section provides a general discussion of factors that may have contributed to the decline of the dwarf wedge mussel in the various Atlantic slope drainages within its range.

IIIzDoundnient The damming and channelization of rivers throughout the species range has resulted in the elimination of much formerly occupied habitat.

For example, dams have converted much of the Connecticut River mainstream into a series of impoundments (Master 1986).

Immediately uDstream from each dam, conditions (including heavy silt deposition and low oxygen levels) are inimical to mussel species such as the dwarf wedge mussel.

Immediately downstream from these dams, daily water level and water temperature fluctuations resulting from intermittent power generation and hypoliunetic discharges are also stress.. ~) to mussels (Master 1986).

Some extreme variations in flow have been observed below dams on the Ashuelot River in New Hampshire.

Master (1992, in ]J~t.) indicates that mollusks, including the dwarf wedge mussel, have been stranded by extreme low water on two recent occasions once when water discharge was lowered from over 100 CFS to 10 CFS in one day, and once in the summer of 1991 when a dam in Keene was under repair.

11

Hypolimnial discharges from reservoirs produce cold tailwater conditions that alter the typical fish and benthic assemblages (Fuller 1974).

Fuller stressed that these changes associated with inundation adversely affect both juvenile and adult mussels and also alter the native fish fauna, eliminating possible fish hosts for glochidia.

Effects of dams on mussel habitat have not been entirely adverse.

Some water supply reservoirs have protected watersheds and, therefore, high quality waters downstream.

Populations of dwarf wedge mussels and other mussel species are often especially dense below mill dams and beaver dams (W. Adams, Army Corps of Engineers, pers. corn.)

Siltation Siltation, generated by road construction, agriculture, forestry activities, and removal of streambank vegetation is considered to be an important factor in the decline of many freshwater mussel species, including the dwarf wedge mussel.

Sediment loads in rivers and streams during periods of high discharge may be abrasive to mollusk shells.

Erosion of the periostracum allows carbonic and other acids to reach and corrode underlying shell layers (Harman 1974).

Feeding mollusks respond to heavy siltation by instin~i-,e closure of their valves, since irritation and clogging of the gills and other feeding structures occurs when suspended sediments are siphoned from the water column (Loar ~ ni.

1980).

Although mussels possess the ability to secrete mucus to remove silt from body tissues, Ellis (1936) observed dying mussels with excessive quantities of silt in their gills and mantle cavities.

Freshwater mussels are long-lived and sedentary, with limited ability to move to more favorable habitats when silt is deposited over mussel beds.

Ellis (1936) found that mussels could not survive in substrate 12

on which silt (0.6-2.5 cm) was allowed to accumulate; death was attributed to interference with feeding and to suffocation.

In this same study, Ellis determined that siltation from soil erosion reduced light penetration, altered heat exchange in the water, and allowed organic and toxic substances to be carried to the bottom where they were retained for long periods of time.

This resulted in further oxygen depletion and possible absorption of these toxicants by mussels (Harman 1974).

Erosion and siltation resulting from land clearing and grading, and construction of bridges, roads, and other structures may be especially damaging to the dwarf wedge mussel s habitat.

For

instance, in Massachusetts, a dwarf wedge mussel population was decimated in one small stream when the construction of a small bridge resulted in accelerated sedimentation and erosion which buried and killed many of the bivalvest (Smith 1981).

Paradoxically, some bank erosion control measures such as riprapping may also adversely affect the species.

A significant portion of one of the extant Connecticut River populations was eliminated in 1987 by burial under rock riprap placed along the shore of a Vermont State park.

Pollution The co.. i-uing decline and ultimate loss of the dwarf wedge mussel from most of its historical sites can best be explained by agricultural, domestic, and industrial pollution of its aquatic habitat.

Mussels are known to be sensitive to potassium (a common pollutant associated with paper mills and irrigation return water),

zinc, copper, cadmium, and other elements (Havlik and Marking 1987).

Pesticides,

chlorine, excessive nutrients, and silt carried by agricultural runoff also present a threat to this species.

13

No mussels survive in several

large, undammed sections of the Connecticut and Delaware River drainages where water pollution has exacted a heavy toll on the benthic fauna.

Even where water quality has improved, as in the lower Connecticut

River, chemicals trapped in the sediments inhabited by mussels may impede the recovery of sensitive species (Master 1986).

One of the largest known remaining populations of the dwarf wedge mussel occurs where the Ashuelot River meanders through a golf course.

This population has undergone a dramatic decline over the past 10-30 years.

The continuing decline of the dwarf wedge mussel at this site, particularly downstream of the golf course, may well be attributed to fungicides, herbicides, insecticides, and fertilizers applied to the golf course and to agricultural runoff from abutting corn fields and pastures (Master 1986).

It has been suggested that elevated cadmium levels, which have been found in the Ashuelot for short periods of time, may also be a contributing factor in this decline (S. von Qettingen, U.S. Fish and Wildlife Service, pars.

comm.).

In this case, the elevated cadmium levels appear to result from cleaning the gates on the Surry Mountain Dam, just upstream of the mussel population.

Pollutants may also affect the mussels indirectly; nitrogen and phosphorus input cause organic enrichment and, if extreme, oxygen depletion.

Acid rain may mobilize toxic metals and lead to decreased alkalinity which is inimical to most mussels.

Increased acidity may have c~i.tcibuted to the recent decline of the dwarf wedge mussel in the Fort River in Massachusetts (D. Smith, University of Massachusetts Museum of Zoology, pars.

corn.).

Several studies have investigated the effects of specific chemicals and heavy metals on mussels.

Fuller (1974) reviewed the effects of

arsenic, cadmium, chlorine, copper, iron, mercury, nitrogen, phosphorus, potassium, and zinc on naiads.

Of the heavy metals, zinc was noted as the most toxic, whereas copper, mercury, and silver were less harmful.

Goudreau (1988) studied the effects on aquatic 14

mollusks of chlorinated effluent from sewage treatment plants.

She found that recovery of mollusk populations may not occur for up to two miles below the discharge point.

Imlay (1973) studied the effects of different levels of potassium, an industrial pollutant associated with paper mills, irrigation return water, and petroleum brine.

The maximum level of potassium which most mussel species could tolerate was 4 to 10 mg/l.

Salanki and Varanka (1978) found that insecticides have significant effects on mussels.

Low concentrations of lindane (.006 gIl),

phorate (.008 g/l),

and trichlorfon

(.02 g/l) caused a 50 percent reduction in siphoning activity, and 1 g/l phorate or 1 ml/l trichlorfon were lethal concentrations.

Recent studies on contaminants have focused primarily on heavy metal effects on mussels.

Mathis and Cummings (1973) investigated concentrations of certain heavy metals (copper, nickel,

lead, chromium, zinc, cobalt, cadmium) in the sediments, water, mussels, fishes, and tubificids in the Illinois River.

Mussels analyzed (Fusconaia flava, Amblema olicata, Ouadrula auadrula) contained higher concentrations of all metals than the water and lower concentrations than sediments.

Mussels concentrated zinc to a greater degree than fishes or tubificids; all other metals were accumulated to intermediate concentrations.

Salanki and Varanka (1976) found that the rhythmic activity (siphoning) of hn~2nL~

~ygn~

was reduced by 10 percent when exposed to l0~~ zw/l of copper

sulfate, tne chemical was lethal at 10 mg/l.

Havlik and Marking (1987) indicated that long-term exposure of mussels to concentrations of copper as low as 25 parts per billion (ppb) was lethal.

Salanid (1979) investigated the behavior of Anodonta ~ygn~,

subjected to certain heavy metals (mercury and cadmium), herbicides, and pesticides (paraquat,

lindane, phosphamidon, and phorate).

The siphoning period of this species was reduced at some concentrations and the metabolic rate decreased.

Manly and George (1977) collected Anodonta anatina from the River Thames and determined the distribution of zinc, nickel, lead, cadmium, copper, and mercury in 15

body tissues.

Zinc and copper were most highly concentrated in the mantle, ctenidia (gills),

and kidneys; nickel levels were highest in the kidneys; lead in the digestive gland and kidneys; cadmium in the ctenidia, digestive gland, and gonads; and mercury in the kidneys.

Recent studies by Keller and Zam (1991), using juvenile Anodonta jjn~~iiIi, have shown that freshwater mussels are quite sensitive to metal pollution.

Acute toxicity tests, using juvenile mussels reared in the laboratory, were performed for the following six metals:

cadmium, chromium, copper, mercury, nickel, and zinc.

Keller and Zam concluded that, overall, mussels were as sensitive to metals as DaDhnia, but more sensitive than commonly tested fish and aquatic insects (Table 2).

Other Factors Land use changes throughout watersheds supporting the dwarf wedge mussel, especially along riparian corridors, may affect the species in a multitude of ways.

The removal of streambank vegetation affects both the physical and biological processes of the waterways.

Tree removal alters the amount of organic material and light reaching the stream, impacting both temperature and dissolved oxygen, which are critical factors for both fish and mussels.

The floodplain biomass can also help buffer the stream from pollutants.

Many of the thre~ts identified abov~a could be mitigated most efficiently by protecting the floodplain.

The invasion of the Asian clam (Corbicula fluminea) may be a significant threat to the dwarf wedge mussel.

The Asian clam is one of 204 introduced mollusk species in North America (Dundee 1969).

It was first discovered in the United States in the Columbia River, Oregon, in 1939.

It appeared inCalifornia in the 1940s and 1950s, in the Ohio/Mississippi and Gulf of Mexico drainages in the 1960s and 1970s, and in the Atlantic drainage in the 1970s and 1980s (Clarke 1988).

Once established in a river, Corbicula fl1~jj~

16

populations achieve high densities and expand rapidly.

Densities of 1,000/rn2 in the James River, Virginia (Diaz 1974), the New River, Virginia (Rodgers et al. 1977), and the Tar River, North Carolina (Clarke 1983), and densities of 10,000/rn2 in the Altanaha River in Georgia (Gardner ~

~.

1976) have been reported.

Clarke (1988) indicates that Corbicula was first introduced into the James River in 1971 near Hopewell, Virginia, about 15 miles below Richmond, and by 1984 had spread 195 miles upstream (an average of 15 miles per year).

Malacologists are now concerned about the possibility of a competitive interaction between Asian clams and native bivalves.

Quantitative studies by Cohen ~

~j.

(1984) support the hypothesis that an extensive C. fluminea bed in a reach of the Potomac River removed 40-60% of the phytoplankton in this reach.

It is not unreasonable to conclude that C. fluminea has the potential to deplete the food supply of unionids.

A similar threat may be posed by the recent invasion of the zebra mussel (Dreissena ~olvmorDha)

Although not yet known to be present in any of the rivers supporting the dwarf wedge mussel, the zebra mussel is expanding its range rapidly and can be expected to arrive in some of these rivers in the near future.

Mussel die-off s, the cause of which remains unknoI,m, may be a threat to the dwarf wedge mussel.

Since 1982 biologists and commercial musselmen have reported extensive mussel die-of fs in rivers and lakes throughout the United States.

Kills have been documented from the Clinch River (Virginia),

Powell River (Virginia, Tennessee),

Tennes~ e RLver (Tennessee), Grand River (Oklahoma), the Upper Mississippi River (Wisconsin to Iowa), and rivers in Illinois, Kentucky, and Arkansas (USFWS 1987).

Lake St. Clair (Michigan),

Chatauqua Lake (New York), and Court Oreilles Lac (Wisconsin) have also been affected.

The cause is unknown, but numerous species of mussels are involved, including several commercially important and Federally listed species (USFWS 1987).

A large mussel die-off has occurred in at least one river supporting the dwarf wedge mussel

the Tar River in North Carolina.

Personnel involved in a survey for the endangered Tar River spinyrnussel in April 1986 dicovered hundreds 18

of freshly dead and recently dead juvenile and adult mussels of various species at two locations in the Tar River below Rocky Mount, North Carolina (USFWS 1987).

Most of the dwarf wedge mussel populations are small, and all are geographically isolated from each other.

This isolation restricts the natural interchange of genetic material between populations.

The small population size also reduces the reservoir of genetic variability within populations.

It is likely that several of these populations are now below the level required to maintain long-term genetic viability.

Furthermore, the small size of many of the dwarf wedge mussels populations makes the species especially vulnerable to overcollecting.

Table 3 summarizes the status and extent of each extant dwarf wedge mussel population, and indicates the known threats current or potential to each population.

These threats are keyed to the following list.

KEY TO MMOR THREATS:

1.

Point sources of pollution 2.

Non-point chemical pollution 3.

Sedimentation from forestry operations 4.

Sedimentation from agriculture 5.

Competition from exotic species 6.

£..-x~ resource modification via forest overstory removal 7.

Discharge rate modifications 8.

Population density too low to allow successful reproduction 9.

Population fragmentation 10.

Significant point source non-compliance 11.

Residential, highway, or industrial development 12.

Reservoir construction 13.

Possible landfill construction near waterbody 14.

Toxic spill associated with highway or railroad 15.

Headwater channelization and stream improvement projects 19

)

)

Table 3. Status of Dwarf Wedge Mussel Populations POPULATION STATUS1 REPRODUCING2 MAJOR THREATS3 APPROXIMATE EXTENT Connecticut River Drainage Connecticut River (5 sites but one population) -- Sullivan County, NH and Windsor County, VT Ashuelot River -- Cheshire County, NH fair to good fair to poor, declining smali numbers (since 1988 very few juveniles found) unknown (no evidence of reproduction in 1991 and 1992) 1, 2, 4, 7, 9, 11, 15 1, 2, 6, 7, 11, 16 Muddy Brook -- Hartford County, CT poor no 1, 2, 3,6,8,9,11 Delaware River Drainage Neversink River -- Orange County, NY stable, verygood (largest population)

Timckahoe Creek (Choptank River) Drainage Norwich Creek QueenAnnes and Talbot Counties, MD Long Marsh Ditch -- Queen Annes and Caroline Counties, MD poor poor no no 2, 4, 8, 11, 17 2,3,4,8,15 0.5 mile 3 miles (scattered individuals)

Potomac River Drainage McIntosh Run -- St. Marys County, MD Nanjemoy Creek -- Charles County, MD Aquia Creek -- Stafford County, VA fair (small population) fair (small population) fair to good yes yes unknown 11 2,3,4,11 3 miles 1 mile Approx. 0.5 mile 1

Based on information provided by those individuals from each state or region most familiar with their respective populations.

2 Evidence of reproduction found, i.e., individuals less than 5 years of age or gravid.

~

See key on preceding page.

16-18 miles 1.5 miles yes 1 mile 1,2,4,7, 13 5 miles

)

Table 3. Status of Dwarf Wedge Mussel Populations (continued)

POPULATION STATUS REPRODUCING MAJOR THREATS APPROXIMATE EXTENT York River Drainage South Anna River -- Louisa County, VA Nottoway River Drainage Nottoway River -- Nottoway and Lunenberg Counties, VA Tar River Drainage Tar River -- Granville County, NC

~CedarCreek -- Franklin County, NC Crooked Creek -- Franklin County, NC Stony Creek -- Nash County, NC Neuse River Drainage Little River

-- Johnston and Wake Counties, NC Swift Creek -- Johnston County, NC Turkey Creek -- Nash and Wilson Counties, NC Moccasin Creek -. Nash, Wilson, and Johnston Counties, NC Middle Creek -- Johnston County, NC poor poor very good (largest in NC) poor good poor fair to good good good good poor/fair unknown unknown yes no yes no yes yes yes yes no 3, 4, 8, 11 3, 4, 8, 11, 14 2, 9, 11, 14 1, 2, 3, 4, 5, 8, 9, 11, 14 3,4,6,9 1, 2, 4,8,9, 11 2, 3, 4, 5, 6, 9, 11, 12, 14 1, 2, 3,4,5,6,7,9, 11, 14 1, 2, 3, 4, 5, 6, 9, 11, 12,14 1, 2, 3, 4, 5, 6, 9, 11, 12,14 1, 2, 3, 4, 5, 8, 9, 11, 14 Approx. 0.5 mile Approx. 0.5 mile 10-15 miles 1 mile 1-2 miles 1 mile 10-20 miles

> 15 miles 5-6 miles 6-7 miles 1-2 miles

)

)

PART H: RECOVERY RECOVERY GOAL The goal of this recovery plan is to maintain and restore viable populations of Alasmidonta heterodon to a significant portion of its historical range in order to remove the species from the Federal list of endangered and threatened species.

This can be accomplished by (1) protecting and enhancing habitat containing A. heterodon populations, and (2) establishing or expanding populations within rivers and river corridors that historically contained this species.

RECOVERY OBJECTIVES Objective 1.

Reclassify Alasmidonta heterodon from endangered to threatened status when the likelihood of extinction in the foreseeable future has been eliminated according to the following criterion:

A.

Populations of A. heterodon in the mainstem Connecticut River, Ashuelot River, Neversink River, upper Tar River, Little River,

-rift Creek (Neuse system), and Turkey Creek, as well as populations in at least six other rivers (or creeks) representative of the species range, must be shown to be viable1.

This will require monitoring the occupied river reach over a 10-15 year period during which adequate population numbers, population stability, and evidence of recent recruitment (specimens age five or younger) are demonstrated.

1 Viable population -- a population containing a sufficient number of reproducing adults to maintain genetic variability and in which annual recruitment is adequate to maintain a stable population.

23

Objective 2.

Remove Alasmidonta heterodon from the Federal list of endangered and threatened species when the following additional criteria have been met:

B.

At least ten of the rivers or creeks referred to in criterion A must support a viable population widely enough dispersed within its habitat such that a single adverse event in a given river would be unlikely to result in the total loss of that rivers population.

Meeting this criterion will require significant expansion of populations in most of the rivers.

These rivers/populations should be distributed throughout the current range of the species, with at least two in New England, one in New York, and four to the south of Pennsylvania.

C.

All populations referred to in criteria A and B must be protected from present and foreseeable anthropogenic and natural threats that could interfere with their survival.

RECOVERY TASKS 1.

Collect basic data needed for protection of Alasmidonta heterodon populations 1.1 Conduct additional population and habitat surveys 1.11 Conduct studies of species distribution and status A considerable effort has been made over the past several years to locate extant dwarf wedge mussel populations.

However, because of the wide distribution of this species on the Atlantic

slope, some sites remain to be surveyed.

These include the Connecticut River in the Thetford and Bloomfield/

4 24

Weathersfield areas in Vermont, and sections of the Connecticut River in Massachusetts.

Other Connecticut River basin sites in need of surveys include Sugar River, Cold River, and Muscoma River in New Hampshire.

In New York and New Jersey, the Upper Wallkill basin, Rondout Creek, the Ten Mile River, and the east and west branches of the Delaware River should be searched.

To the south, a number of rivers and streams remain to be surveyed in Virginia,. including sections of the Rappahannock, Pamunkey, Mattaponi, Shenandoah, Appomatox, Rivanna, and Pedlar Rivers, and several areas in the James and Chowan River basins.

The total extent of each population must also be determined.

1.12 Identify an initial list of potential reintroduction sites.

Observations of habitat conditions and species diversity while implementing task 1.11 should provide an initial indication of potential sites for future reintroduction efforts.

Fish surveys may be needed later to determine whether host fish are present in sufficient numbers (following completion of Task 4.1).

1.2 Identify essential habitat and key areas in need of protection.

Essential habitat can be delineated in the best known rivers/streams, including the Connecticut and

Ashuelot, and other wellknown sites, with little additional surveying.

Delineation of essential habitat in most other rivers and creeks must await more definitive survey data developed during implementation of Task 1.11.

25

1.3 Identify and determine the sicinificance of specific threats faced by the species such as Desticide contamination.

siltation.

acidification, and municipal and industrial effluents 1.31 Review literature and compile existina information on point and nonpoint pollution sources: map pollution sources.

Point sources of pollution

and, where feasible, non-point sources should be mapped in each of the watersheds supporting populations of A. heterodon.

Where large watersheds are involved, it may be necessary to focus pollution-source mapping in the stream section within 10 to 20 miles of known dwarf wedge mussel population sites.

1

• 32 Conduct water aualitv and contaminants sam~l inc~ at extant population sites and ootential reintroduction sites.

This sampling program will determine the presence of contaminants at specific sites.

Contaminants found at extant population sites could be the subject of further study, as called for in Task 1.33.

Presence of significant levels of toxic contaminants at potential transplant sites would eliminate these sites from further consideration.

1.33 Conduct toxicity tests and bioassavs of pesticides and other contaminants usinci surrociate mussel species.

Because of the known intensive use of pesticides at the golf course adjacent to the Ashuelot River site, priority should be given to tests of turf/golf course chemicals.

EPA has funded some work to develop pesticide toxicity test protocols for freshwater mussels (Johnson ~

nL.

1988), and would be a logical agency to carry out further testing.

26

2.

Preserve A. heterodon populations and occupied habitats 2.1 Continue to utilize existinci lecrislation and reaulations (Federal and State Endancrered Species Acts. water aualitv reciulations.

stream alteration reaulations.

etc.~

to protect the species and its habitats.

Known populations cannot be protected without full enforcement of existing laws and regulations.

Land management and regulatory agencies that may have important roles to play in assisting the U.S. Fish and Wildlife Service with the recovery of this species include the U.S. Environmental Protection Agency, Soil Conservation Service, Army Corps of Engineers, Federal Energy Regulatory Commission, State natural resource agencies, and local planning and zoning departments.

FERC may have an important role in reviewing low flow releases from hydro-electric facilities on the Connecticut River during rel icensing.

The assistance of EPA and State water quality control agencies may be particularly important since strict conditioning and enforcement of NPDES permits and non-point discharge permits will be essential for the recovery of this species.

In addition, it will be the responsibility of EPAs pesticide labeling program to implement alternatives to avoid pesticide impacts on the dwarf wedge mussel, as required by Section 7 of the Endangered Species Act.

Data developed by Task 1.33 should be helpful in this process.

2.2 Determine and implement protection strateciies for essential habitat areas identified in Task 1.2 2.21 Encouracre additional lecral protection throucrh wild and scenic river desianation.

establishment of reaulations to protect water aualitv.

etc.

The U.S.

Fish and Wildlife Service will work with the National Park Service and State agencies to consider special status for river and stream reaches 27

providing prime habitat for this mussel.

For

instance, in Virginia the Water Control Board is now considering designation of specific river/stream reaches for the protection of this endangered species.

Additional legislation requiring or providing incentives for riparian buffer strips may be needed.

2.22 Work with landowners.

local aovernment officials and reaulatorv aaencv representatives to solicit suPport for protection of the species and mitigation of impacts to the species and its essential

~

Owners of riparian lands and local governments and regulatory agency officials will be informed of the species presence and the importance of protecting its habitats.

Zoning agencies will be encouraged to develop regulations or guidelines to protect aquatic habitats.

Landowners will also be encouraged to work with the SCS and State agriculture agencies to develop measures to reduce sediment erosion, and runoff of pesticides toxic to mussels.

2

• 23 Provide lonciterm protection of essential habitats throucrh acouisition.

reaistrv. manaaement

~g~menLs.

and the establishment of stream buffer zones.

Where feasible, acquisition would provide the most effective protection for the species and its habitat, although a lesser degree of protection could be provided by registry and management agreements (including establishment of buffer zones) with private landowners.

Management agreements or other mechanisms are needed to control erosion caused by agriculture, timber cutting, and other land-use activities adjacent to stream banks.

Where riparian lands remain in private ownership, 28

landowners should be encouraged to install fencing to limit access by farm animals, and to leave agricultural and silvicultural buffer strips along streambanks.

A major role in this process could be played by SCS and related State programs through installation of agricultural best management practices and development of buffer zones under the conservation reserve program of the 1990 Food Security Act.

2.24 DeveloD an interim a~~roach to deal with pesticide usacre not currently covered by EPA/NS endancrered species consultations.

Special attention must be given to pesticides used in agriculture, silviculture and turf management adjacent to dwarf wedge mussel habitats.

Interim measures should be developed to protect freshwater mussels until EPA/FWS consultations and EPA labeling requirements have been completed.

This is especially crucial for sites such as the Ashuelot River, where pesticides are thought to be a key factor in the species decline.

3.

~

protection of the species throucrh development of an educational awareness prociram

.,. I Develop and distribute informational and educational materials such as slide/tape shows and brochures to school children.

civic ciroups. and the cxeneral public.

Many schools are incorporating endangered species as subjects in their curricula, and they welcome new material.

The development and distribution of material focusing on the protection of the dwarf wedge mussel s aquatic environment will enable a broad audience to become familiar with this species and its habitat.

29

3.2 DeveloP and distribute informational and educational materials aimed specifically at farmers and other pesticide users.

This educational program should be developed under the leadership of EPA with input from State agriculture agencies.

This program should include information on alternative methods of pest control or less hazardous pesticides to avoid negative impacts on the dwarf wedge mussel and other endangered species.

3.3 Continue to facilitate the initiation of River Watch Programs in dwarf wedcie mussel rivers.

River Watch Programs are volunteer programs established to provide information about existing and potential water quality problems.

These programs promote a greater awareness of the importance of the aquatic systems being monitored and, in turn, involve citizens and students in the protection of these systems.

4.

Conduct life history studies and identify ecological reauirements of the species 4.1 Conduct life history research on the species to include reproduction, food habits.

acre and arowth. mortality factors.

etc.

Life history research, including population demographics, development of an age/length key, and the determination of host fishes, is currently underway at the V?I&SU.

Supplementary studies may be needed to determine host species for dwarf wedge mussel populations in New England and New York.

4.2 Characterize the species habitat reauirements (relevant physical. biolocrical.

and chemical com~onents~

for all life history stages.

Elements that should be considered include:

current speed, water depth, substrate grain

size, firmness and embeddedness of substrate, substrate stability, water temperature, and water quality factors 30

such as nitrate and potassium levels, dissolved

calcium, dissolved oxygen, and pH.

The studies underway at VPI&SU will provide this information for southern populations.

Additional studies may be needed to characterize features throughout the species range.

5.

Determine the feasibility of re-establishinci populations within the species historical rancre and. if feasible, introduce the species into such areas.

The present range of the dwarf wedge mussel is much smaller than it was historically.

There may be areas within the species former range that could support re-established populations.

5.1 Determine the need. appropriateness, and feasibility of auamentincr and expandina existinci populations.

Several populations are likely below the number needed to maintain long-term viability.

These populations may be able to expand naturally if environmental conditions are improved; however, some populations may need to be supplemented to reach a viable size.

Populations for this task will be selected based on present population size, habitat

quality, and the likelihood of long-term benefits from the effort.

At any site selected for augmentation or re-establishment, the host fishes must be present in adequate numbers.

Task 1.12 should provide the necessary information; the list of potential reintroduction sites generated in that task will be refined and feasibility will be determined on a site-specific basis.

5.2 Develop a successful techniaue for reestablishinci and aucimentina populations.

This task is included in several other mussel recovery plans.

Techniques developed for those species may wor)~ for the dwarf wedge mussel as well.

31

5.3 Coordinate with appropriate Federal and State acrency personnel.

local croverriments. and interested parties to select streams that may be suitable for auamentation and reintroduction and can be effectively Protected from further threats.

Results of Task 1.32 should provide preliminary information on potential sites.

Special attention should be focused on sections of the Connecticut River to be included in the Silvio Conte National Wildlife Refuge.

5.4 Where appropriate, reintroduce the species within its historical rancre and evaluate success 5.5 Implement the same protective measures for any introduced populations as outlined for established populations in

- I~.

6.

Develop and implement a prociram to monitor population levels and habitat conditions at Present and introduced population sites.

In light of the dwarf wedge mussels dramatic decline in the Ashuelot River, this task is critical.

6.1 Develop a monitorinci protocol.

A monitoring protocol will need to be established for all major A. heterodon sites.

At a minimum, this will involve a semi-quantitative approach using mussels observed per unit effort.

Quadrat

~mpling should be used, where appropriate, to provide a more quantitative indication of population trends and age-class distribution.

6.2 Implement monitoring.

This task will begin with a baseline quantitative survey (including age-class distribution) and continue with systematic monitoring of all significant populations every two to three years.

32

7.

Periodically assess overall success of the recoverv ~roaram and recommend appropriate actions (chancies in recoverv objectives downlistincr.

implementinci new measures.

other studies. etc. ~

An informal recovery implementation group composed of representatives of the U.S. Fish and Wildlife Service, State agencies, conservation groups, etc., will be established to assist in implementing this task as well as other aspects of the recovery plan.

The recovery plan will be evaluated to determine if it is on track and to recommend future actions.

As more is learned about the species, the recovery objectives may need to be modified.

33

Table 4

• STEPDOUN RECOVERY OUTLINE 1.

Collect 1.1 basic data needed for protection ofAlasmidonta Jaeterodon populations.

Conduct additional population and habitat surveys forA. heterodon.

1.11 Conduct studies of species distribution and status.

1.12 Identify an initial list of potential reintroduction sites.

1.2 Identify essential habitat and key areas in need of protection.

1.3 Identify and determine significance of specific threats faced by the species such as pesticide contamination, siltation, acidification, and municipal and industrial effluents.

1.31 Review literature and compile existing information on point and non-point pollution sources; map pollution sources.

1.32 Conduct water quality and contaminants sampling at extant population sites and potential reintroduction sites.

1.33 Conduct toxicity tests and bioassays of pesticide and other contaminants using surrogate mussel species.

2.

Preserve A. heterodon populations and occupied habitats.

2.1 Continue to utilize existing legislation and regulations to protect the species and its habitats.

2.2 Determine and implement protection strategies for areas identified in Task 1.2.

2.21 Encourage additional legal protection through wild and scenic river designation, and establishment of regulations to protect water quality.

2.22 Work with l:~ndowners, local government officials, and regulatory agency representatives to solicit support for protection of the species and mitigation of impacts to the species and its essential habitats.

2.23 Provide long-term protection ofessential habitats through acquisition, registry, management agreements, and the establishment of stream buffer zones.

2.24 Develop an interim approach to deal with pesticide usage not currently covered by EPA/FWS endangered species consultations.

3.

Encourage protection of the species through development of an educational awareness program.

3.1 Develop and distribute informational and educational materials, such as slide/tape shows and brochures to school children, civic groups, and the general public.

34

Table 4

(continued).

STEPDOWN RECOVERY OUTLINE 3.2 Develop and distribute informational and educational materials aimed specifically at farmers and other pesticide users.

3.3 Continue to facilitate the initiation of River Watch Programs in dwarfwedge mussel rivers.

4.

Conduct life history studies and identify ecological requirements of the species.

4.1 Conduct life history research on the species to include reproduction, food habits, age and growth, mortality factors, etc.

4.2 Characterize the species habitat requirements (relevant physical, biological, and chemical components) for all life history stages.

5.

Determine the feasibility of re-establishing populations within the species historical range and, if feasible, introduce the species into such areas.

5.1

- Determine the need, appropriateness, and feasibility of augmenting and expanding existing populations.

5.2 Develop a successful technique for re-establishing and augmenting populations.

5.3 Coordinate with appropriate Federal and State agency personnel, local governments, and interested parties to determine which of the streams identified in Task 1.12 are suitable for augmentation and reintroductions and most easily protected from further threats.

5.4 Where appropriate, reintroduce the species within its historical range and evaluate success.

5.5 Implement the same protective measures for any introduced populations as outlined for established populations.

6.

i~..&op and implement a program to monitor population levels and habitat conditions of presently established and introduced populations.

6.1 Develop a monitoring protocoL 6.2 Implement monitoring.

7.

Periodically assess overall success of the recovery program and recommend appropriate actions (changes in recovery objectives, downlisting, implementing new measures, other studies, etc.).

35

LITERATURE CITED Clarke, A.H.

1981a.

The Tribe Alasmidontini (Unionidae: Anodontinae),

Part I:

Pecrias, Alasmidonta, and Arcidens.

Smithsonian Contributions to Zoology, No. 326.

101 pp.

Clarke, A.H.

1981b.

The Freshwater Mollusks of Canada.

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446 pp.

Clarke, A.H.

1988.

Aspects of Corbiculid-unionid sympatry in the United States.

Malacology Data Net 2(3/4): 57-99.

Cohen, R.R., P.V. Dresler, E.J. Phillips, and R.L. Cory.

1984.

The effect of the Asiatic clam, ~Qrki~lA1~~13~in~,

on phytoplankton of the Potomac River, Maryland.

Limnol.

Oceanogr., 29(1): 170-180.

Diaz, R.J.

1974.

Asiatic clam, Corbicula ~fl~J&n~i&(Philippi) in the tidal James River, Virginia.

Cheasapeake Sci.

15(2):118120.

Dundee, D.S.

1969.

Introduced molluscs of the United States.

Malacologia.

9(1) :264.

Ellis, M.M.

1936.

Erosion silt as a factor in aquatic environments.

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Fuller, S.L.H.

1974.

Clams and mussels 215273 IN: C.W. Hart, Jr.

and S.L.H.

ecology of freshwater invertebrates.

(Mollusca: Bivalvia).

Pages Fuller (eds.)

Pollution Academic Press, NY.

Fuller, S.L.H.

1977.

Freshwater and terrestrial mollusks.

IN:

J.E.

Cooper ~

~.,

(eds.),

Endangered and threatened plants and animals of North Carolina.

NC State Museum of Natural History, Raleigh, NC.

pp. 143194.

Gardner, J.A., Jr.,

W.R. Woodall, Jr.,

A.A. Staats, Jr.,

and J.F.

Napoli.

1976.

The invasion of the Asiatic clam ~Q+/-+/-~1~ ~n+/-1mJ~i&

Philippi in the Altamaha River, Georgia.

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90(3): 117125.

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S. E.

mollusks and M.S. Thesis.

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and State Univ., Blacksburg, VA.

Harman, W.N.

1974.

The effects of reservoir construction and canalization on the mollusks of the upper Delaware watershed.

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, and L.L. Marking.

1987.

Effects of contaminants on Naiad (Unionidae):

A review.

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Washington DC.

20 pp.

Bull.

37

Imlay, M.J.

1973.

Effects of potassium on survival and distribution of freshwater mussels.

Malacologia 12:97113.

Johnson, I.C.,

A.E. Keller, and S.G. Zam.

1988.

Early life stage protocols for the assessment of pesticide effects to freshwater mussels.

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Unpubl. Rep.

Keller, A.E., and S.G.

Zam.

1991.

The acute toxicity of selected metals to the freshwater mussel, Anodonta imbecilis.

Environmental Toxicology and Chemistry, 10:539546.

Lea, I.

1829.

Description of a New Genus of the Family of Naiades (etc.).

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Society, new series.

3:403456.

Loar, J.M.,

L.L. Dye, R.R. ~rner, and S.G. Hildebrand.

1980.

Analysis of environmental issues related to smallscale hydroelectric development 1.

Dredging.

ORNL, Environ. Sci. Div.

Publ. No.

1565, Oak Ridge, TN.

134 pp.

Manly, R. and W.O. George.

1977.

The occurrence of some heavy metals in populations of the freshwater mussel Anodonta anatina (L.)

from the River Thames.

Environ. Pollut.

14:139-154.

Master, L.

1986.

Alasmidonta heterodon; results of a global status survey and proposal to list as an endangered species.

A report submitted to Region 5 of the U. S. Fish and Wildlife Service.

10 pp.

and appendices.

Mathis, B.J. and T.F. Cummings.

1973.

Selected metals in sediments, water, and biota in the Illinois River.

Water Pollut. Contr. Fed.

45:15731583.

Ortmann, A.E.

1914.

Studies in najades.

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Rodgers, J.H.,

D.S. Cherry, K.L. Dickson, and J. Cairns, Jr.

1977.

Invasion, population dynamics, and elemental accumulation of Corbicula fluminea in the New River at Glen Lyn, Virginia.

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Salanki, 3.

1979.

Behavioural studies in mussels under changing environmental conditions.

Symp. Biol. Hung.

19:169-176.

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and I. Varanka.

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Salanki, 3. and I. Varanka.

1978.

Effect of some insecticides on the periodic activity of the freshwater mussel (Anodonta ~ygl3~, L.).

Acta. Biol. Acad. Sci.

Hung. 29(2):173180.

Simpson, C.T.

1914.

A descriptive catalogue of the naiades or pearly freshwater mussels, Vol.

13.

Bryant Walker, Detroit.

38

Smith, D.

1981.

Selected freshwater invertebrates proposed for special concern status in Massachusetts (Mollusca, Annelida, Arthropoda).

MA Dept. of Env. Qual. Engineering, Div. of Water Pollution Control.

26 pp.

U.S. Fish and Wildlife Service.

1987.

Tar River spinymussel recovery plan.

U.S. Fish and Wildlife Service, Atlanta, GA.

44pp.

Zale, A.V.

1980.

The life histories of four freshwater lampsiline mussels (Mollusca: Unionidae) in Big Moccasin Creek, ~ssell

County, Virginia.

M.S. thesis.

Virg. Polytech. Inst.

State Univ.,

Blacksburg, VA 256 pp.

39

PART Ill: IMPLEMENTATION SCHEDULE The following Implementation Schedule outlines actions and estimated costs of the recovery program.

It is a guide for meeting the objectives discussed in Part II of this plan.

This schedule indicates task priorities, task numbers, task descriptions, duration of tasks, responsible agencies, and estimated costs.

These actions, when accomplished, should bring about the recovery of the species and protect its habitat.

Key to

~

t~t1nn

~

Priorities (r.~1imrn 1

)

.LAULJ.L~LLE~L.

Priority 1

Priority 2 Priority 3 An action that must be taken to prevent extinction or to prevent the species from declining irreversibly in the foreseeable future.

An action that must be taken to prevent a significant decline in species population/habitat quality or some other significant negative impact short of extinction.

All other actions necessary to provide for full recovery of the species.

Key to Acrencv Abbrevi~jQ~s (column 6

)

Army Corps of Engineers Environmental Protection Agency Federal Energy Regulatory Commission National Park Service State Agriculture Department Recovery Implementation Group Soil Conservation Service State Nongame and Endangered Species State Natural Heritage Programs State Water Control Boards The Nature Conservancy Virginia Polytechnic Institute and State University Programs

=

EPA FERC

=

NPS

=

SAGD

=

PIG

=

S~S

=

SNGP

=

SNHP

=

SWCB

=

TNC

=

VPI&SU =

41

)

)

IMPLEMENTATION SCHEDULE DWARF WEDGE MUSSEL February 1993 Priority Task Description Task Number Duration Responsible Agency Cost Estimates, $000 Comments USFWS Other FYi FY2 FY3 1

Conduct additional population and habitat surveys.

1.1 3 years Region 5 Region 4 SNHP, SNGP 30 30 30 1

Identify essential habitat and key areas in need of protection.

1.2 3 years Region 5 Region 4 SNHP, SNGP 2

2 2

2 Review literature and compile information on point and non-point pollution; map poliution sources.

1.31 3 years Region 5 Region 4 SWCB, SNHP, SNOP, EPA 20 20 20 FWS Contaminants Program will have lead.

2 Conduct water quality and contaminants sampling.

1.32 3 years Region 5 Region 4 25 25

+ $25K in FY4.

1 Conduct toxicity tests of pesticides and other contaminants.

1.33 4 years Region 5 Region 4 EPA 30 30 30

+ $30K in FY4.

1 Continue to utilize existing legislation and regulations to protect the species.

2.1 Continuous Region 5 Region 4 SWCB, SNHP, SNGP, COE, EPA, FERC 10 10 10

+ $1OK/yr for 7 more years.

2 Encourage designation of wild and scenic rivers, and regulations to protect water quality.

2.21 7

Region 5 Region 4 SWCB, SNHP, SNGP, NPS 20 30

+ $30K/yr for 3 more years.

1 Work with landowners and others to solicit support for protection of the species.

2.22 Continuous Region 5 Region 4 TNC, SNHP, SNGP, SAGD, SCS 5

5 5

+ $5K/yr for 7 more years.

1 Provide long-term protection of essential habitats.

2.23 10 years Region 5 Region 4 TNC, SNHP, SNGP, SCS 15 30 30 Amount and cost of land acquisition not yet known.

)

)

Dwarf Wedge Mussel Implementation Schedule (r :itinued), February 1993 Priority Task Description I

Task Number Duration Responsible Agency Cost_Estimates, $000 FYi FY2 FY3 Comments USEWS Other 1

Develop an interim approach to deal with pesticide usage.

2.24 1 year Region 5 EPA 2

3 Develop an educational program for school children etc.

3.1 1 year Region 5 Contract or TNC, SNGP, SNHP 5

3 Develop an educational program aimed at pesticide users.

3.2 1 year Region 5 Region 4 SAGD, EPA 10 3

Facilitate river watch programs.

3.3 Continuous Region 5 Region 4 SNIIP, SNGP 1

1

+ $1,000/yr for 7 more years.

1 Conduct life history studies and identify requirements of the species.

4.

2 years Region 5 Contract (VPI&SU)

Already funded ($35K) and underway.

3 Determine feasibility of re-establishing populations within historic range.

5.

5 years Region 5 Region 4 SNHP, SNGP Implementation to be initiated after FY3 at approx. $1SK/yr for 5 years.

1 Monitor populations levels and habitat conditions.

6.

Continuous Region 5 Region 4 SNHP, SNGP 30

+ $30K/yr in FYS, FY8, and FY10.

3 Assess overall success of the program and recommend appropriate actions.

7.

Continuous Region 5 Region 4 RIG

APPENDIX: LIST OF REVIEWERS An asterisk

(*) indicates those reviewers who submitted comments on the Technical/Agency Draft recovery plan.

All conunents were reviewed and incorporated as appropriate into this final recovery plan.

Comments and U.S. Fish and Wildlife Service responses are on file in the Service s Annapolis Field Office.

• William Adams Planning Division Wilmington District, Corps of Engineers P. 0. Box 1890 Wilmington, NC 28402

• John Alderman North Carolina Wildlife Resources Commission Archdale Building 512 N. Salisbury street Raleigh, NC 27611 Marty Abair U.S. Army Corps of Engineers Camp Johnson, Bldg. 10-18 Colchester, VT 05446 William Bartlett Vermont Water Resources Board 58 EState Street Montpelier, VT 05602 Bud Bristow Executive Director Virginia Dept. of Game and Inland Fisheries Post Office Box 11104 Richmond VA ~3~0

• John Bergquist Pesticide Regulation Section Maryland Department ofAgriculture 50 Harry S. Truman Parkway Annapolis, MD 21401 Frankie Brackley-Tolman RFD Marlborough, NH 03455 Richard Biggins U.S. Fish and Wildlife Service Asheville Field Office 100 Otis Street, Rm. 224 Asheville, NC 28801 Dr. Arthur E. Bogan Department of Malacology Academy of Natural Sciences 19th and The Parkway Philadelphia, PA 19103

• Bruce W. Bolick CZR, Inc.

4709 College Acres Drive Wilmington, NC 28403-1725 Richard N. Burton Executive Director State Water Control Board P.O. Box 22243 Richmond, VA 23230

• Sue Bruenderman Virginia Dept. of Game and Inland Fisheries Route 2, Box 54706 Ashland, VA 23005 James W. Chadwick Rhode Island Div. of Fish and Wildlife Field Headquarters Box 218 West Kingston, RI 02892 Philip Christensen State Conservationist USDA, Soil Conservation Service 339 Revell Highway Annapolis, MD 21401 Dr. Arthur H. Clarke 325 E. Bayview Portland, TX 78374 William Debuys Director North Carolina Nature Conservancy P.O. Box 805 Chapel Hill, NC

Mark DesMeules The Nature Conservancy 27 State Street Montpelier, VT 05602 Michael Lipford The Nature Conservancy Virginia Field Office 1110 Rose Hill Drive Charlottesville, VA 22901 Director Office of Hydropower Licensing Federal Energy Regulatory Comm.

825 North Capitol St., NE Washington, D.C. 20426 Delbert F. Downing New Hampshire Water Resources Division 64 North Main Street Concord, NH 03301

• Environmental Protection Agency Envirnomental Fate and Effects Division EEB (T5769C) 401 M Street, SW Washington, DC 20460 Executive Director American Fisheries Society 5410 Grosvenor Lane Bethesda, MD 20814

• Christopher Fichtel Vermont Nongame and Natural Heritage Program Department of Fish and Wildlife 103 South Main St.. 10 South WatcrL

. VT ~)5676 Colonel Frank R. Finch District Engineer Baltimore District, Corps of Engineers P.O. Box 1715 Baltimore, MD 21203 Dan Geiger Bureau of Environment New Hampshire Dept. of Transportation P.O. Box 483 Concord, NH 03302-0483 Andrew G. Gerberich 14830 Basingstoke Loop Centreville, VA 22020 Krista Helmboldt The Nature Conservancy 2 1/2 Beacon Street, Suite 6 Concord, NH 03301 Colonel Richard Johns District Engineer Norfolk District, Corps of Engineers Fort Norfolk 803 Front Street Norfolk, VA 23510 Cliff Lerner Science Department Keene High School Keene, NH 03431

• Laurie Maclvor Maryland Natural Heritage Program Tawes State Office Building 580 Taylbr Avenue Annapolis, MD 21401

• Larry Master Eastern Regional Office The Nature Conservancy 201 Devonshire St., 5th Floor Boston, MA 02110-1402 Dawn McKay Connecticut Natural Diversity DataBase 165 Capitol Avenue Hartford, CT 06106 David McCurdy 26 Greenwood Avenue Keene, NH 03431 Dr. James H. McLean President, American Malacological Union Los Angeles County Museum of Natural History 900 Exposition Boulevard Los Angeles, CA 90007

• David Michaclson Virginia Cooperative Fisheries Unit Department of Fisheries and Wildlife Virginia Polytechnic Insitutue and State University Blacksbur& VA 24061 Larry Morse The Nature Conservancy 1815 N. Lynn Street Arlington, VA 22209

• Dr. RJ. Neves Virginia Cooperative Fisheries Unit Department of Fisheries and Wildlife Virginia Polytechnic Institute and State University Blacksbur& VA 24061 George C. Norris State Conservationist Soil Conservation Service Federal Building 400 N. Eighth Street Richmond, VA 23240

• Jimmie Overton Environmental Management Division North Carolina Dept. ofEnvironmental, Health, and Natural Resources P.O. Box 27687 Raleigh, NC 27611 Raleigh Field7Office US. Fish and Wildlife Service P.O. Box 33726 Raleigh, NC 27636

• Dr. Steven M. Roble Massachusetts Division of Fisheries and Wildlife 100 Cambridge Street Boston, MA 02202

• Earl T. Robb Virginia Department of Transportation 1401 East Broad Street Richmond, VA 23219 Peter Ryner Keene Planning Board 3 Wi4si>~tou &r..ct Keene, NH 03431 Kathy Schneider New York Natural Heritage Program New York Dept. of Environmental Conservation 700 Troy Schenectady Road Latham, NY 12110-2400 Cindy Schultz Virginia Field Office US. Fish and Wildlife Service P.O. Box 480 Mid-County Center White Marsh, VA 23183

• Doug Smith Department of Zoology University of Massachusetts Amherst, MA 01003-0027 Dr. David H. Stansbery Museum of Zoology Ohio State University 1813 N. High Street Columbus, OH 42310 State Conservationist USDA, Soil Conservation Service Federal Building Durham, NH 03824 State Conservationist USDA, Soil Conservation Service Federal Building 310 New Bern Avenue Raleigh, NC 27601 State Conservationist USDA, Soil Conservation Service 69 Union Street Winooski, VT 05405 Judy St. Gelais Keene Conservation Commission 3 Washington Street Keene, NH 02254

• David Strayer Institute of Ecosystem Studies The New York Botanical Gardens BoxAB Millbrook, NY 12545 Virginia Division ofNatural Heritage Main Street Station 1500 E. Main St., Suite 312 Richmond, VA 23219 Julie Victoria Connecticut Dept. ofEnvironmental Protection Sessions Woods Wildlife Management Area P.O. Box 1238 Burlington, CT 06013

• Susi von Qettingen New England Field Office U.S. Fish and Wildlife Service 400 Ralph Pill Marketplace 22 Bridge Street Concord, NH 03301

Ted Watt Arcadia Sanctuary 127 Comb6 Road Easthampton, MA 01027 Patricia C. Weber National Rivers and Trails Branch National Park Service 260 United States Custom House 2nd and Chestnut Streets Philadelphia, PA 19106 Kenneth F. Wich Division of Fish and Wildlife New York State Dept. of Environmental Conservation 50 WolfRoad Albany, NY 12233 Colonel Paul A. Woodbury District Engineer C

Wilmington District, Corps of Engineers P.O. Box 1890 Wilmington, NC 28402