ML20070U996
| ML20070U996 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 01/31/1983 |
| From: | PACIFIC GAS & ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20070U984 | List: |
| References | |
| B-82-408, NUDOCS 8302140117 | |
| Download: ML20070U996 (155) | |
Text
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t DIABLO CANYON POWER PLANT TERMAL EFFECTS MONITORING PROGRAM 1982 AP4RJAL REPORT f January 1983 i
i B-82-408
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8302140117 830128 PDR ADOCK 05000275 R pop
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TABLE OF CONTENTS Section Pggg E X EC UT IVE SU M M ARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I l.0 ! NT R O D UC T I O N . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . l-l 2.0 MONITORING PROGRAM METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 Intertidal Bond Transect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Intertidal 0.25 m2 Rondom Point Contact Quodrat (RPCO) ... 2-l 2.3 Intertidal Algol Scropings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2.4 Intertidal Black Abalone Togging . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2.5 Diablo Cove Block Abolone Survey . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2.6 Intertidal Station Photography Subtask . . . . . . . . . . . . . . . . . . . . 2-6 2.7 Subtidal Sister-Ovodront Procedure: Macroolgo and Macroinvertebrate Counts ........................... 2-7 2.8 Subtidal Fixed Circular Quadrat Procedure:
Inverte bra te Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2.9 Subtidal Rondom Line Point Contact (RLPC) . . . . . . . . . . . . . . . 2-9 2.10 Subtidal Crab Trapping and Togging . . . . . . . . . . . . . . . . . . . . . . . 2-10 2.11 Fish Observations ...................................... 2-10 2.12 Se t t li ng P late . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
. 2.13 in Situ Temperature .................................... 2-16
) 2.14 in Situ Light ........................................... 2-16 d 2.15 in Sit u Wave / Tide Subto sk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18 3.0 MONITORING PROGRAM RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 Intertidal Band Transect (IBT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1.1 Algae.......................................... 3-1 l 3.1.1.1 Endocladio muricato . . . . . . . . . . . . . . . . . . . . . 3-7 l 3.l.l.2 Gastroclonium coulterl .................. 3-8 3.l.l.3 Gigartino conoliculato . . . . . . . . . . . . . . . . . . . 3-13 3.l.l.4 Gigartino papillato ...................... 3-16 3.1.l.5 Iridaea floccido ........................ 3-19 3.1.2 Inver t e bra te s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-23 3.1.2.1 Anthopleuro elegantissimo ............... 3-24 3.1.2.2 Holiotis crocherodii ..................... 3-29 3.1.2.3 Collisello scobro ........................ 3-39 3.1.2.4 Pogu rus spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-41 3.1.2.S Tegulo funebrolls ....................... 3-42 I
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TABLE OF CONTENTS (continued)
Section P_oge 3.2 Intertidal 0.25 m2 Random Point Contact Quadrat (RPCO).... 3-51 3.3 Intertidal Algol Scropings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-51 3.4 Intertidal Block Abalone Togging . . . . . . . . . . . . . . . . . . . . . . . . . 3-51 3.5 Intertidal Block Abolone Survey . . . . . . . . . . . . . . . . . . . . . . . . . . 3-51 3.f. Intertidal Station Photography ........................... 3-51 3.'/ Subtidal Sister Quadrant Procedure:
Macroolgo and Macroinvertebrate Counts . . . . . . . . . . . . . . . . . . 3-56 3.8 Subtidal Fixed Circular Quadrat Procedure: :
Invertebrate Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-56 l 3.9 Subtidal Sister Ovodront Procedure:
Random Line Point Contact (RLPC) . . . . . . . . . . . . . . . . . . . . . . . 3-56 3.10 Crab Trapping ......................................... 3-56 3.10.1 Catch Abundance and Composition . . . . . . . . . . . . . . . . 3-59 3.10.2 Width and Weight Composition .................... 3-60 3.10.3 Mol ting and Growt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-63 3.10.4 Maturity and Reproduction ....................... 3-65 3.10.5 Mark and Recopture Studies ...................... 3-66 3.1l Subtidal Fish Observations .............................. 3-67 3.11.1 Blue Rockfish .................................. 3 3.11.2 Olive Rock fi sh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-75 3.11.3 Block and Yellow Rockfish . . . . . . . . . . . . . . . . . . . . . . . . 3-76 3.11.4 Bococ c i o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-79 3.ll.5 Pointed Greenlings .............................. 3-84 3.11.6 Gro ss Rock fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-87 3.1 1.7 Striped Surfperch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-87 3.1 1.8 Block Surfperch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.11.9 Cobezon ....................................... 3-93' 3.12 Subtidal Settling Plates ................................. 3-96 3.13 in Situ Temperature Monitoring .......................... 3-96' 3.13.1 Subtidal Temperatures . . . . . . . . . . . . . . . . . . . . . 3-100 3.13.2 Intertidal Temperatures . . . . . . . . . . . . . . . . . . . . . . 3-103 3.14 in Situ Solar Irradiance Monitoring . . . . . . . . . . . . . . . . . . . . . . . 3- 106 3.14.1 Sur face Irrodiance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 107 3.14.2 Subtidal Irrodiance ............................. 3-107 3.15 in Si t u Wave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 1 12
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l TABLE OF CONTENTS !
- (ccntinued) !
. Section P_oge j I
4.0 A NC IL' ARY STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 ,
9 i 4.1 Laboratory Heat Treatment Thermal Effects Study . . . . . . . . . . . 4-1
! 4.1.1 M e t hod s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.1.2 R e su l t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
(
, 5.0 LITE RATURE C ITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 t ;
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LIST OF FIGURES Figure Page 2-1 Intertidal and Subtidal Biological Sampling Station Locations .. .... 2-2 2-2 Hypothetical intertidal Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2-3 Diogram of Subtidal Sampling Station .......................... 2-8 2-4 Crab Trapping Station Locations -............................. 2-11 2-5 Subtidal Fish Transect Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 2-6 Sequence of Settling Plate Installation and Replacement . . . . . . . . . . 2-15 2-7 Intertidal and Subtidal Physical Data Recording Stations . . . . . . . . . . 2-17 3-1 Abundance versus Time for Endocladio muricato at +1 ft MLLW .... 3-9 3-2 Abundance versus Time for Endocladio muricata at +3 ft MLLW .... 3-10 3-3 Abundance versus Time for Gastroclonium coulteri a t + 1 f t M LLW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11 3-4 Abundance versus Time for Gastroclonium coulteri a t + 3 f t MLLW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 3-5 Abundance versus Time for Gigartino canaliculato a t + 1 f t MLLW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14 3-6 Abundance versus Time for Gigartino conoliculata a t + 3 f t M L LW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15 3-7 Abundance versus Time for Gigartino papillato at +1 ft MLLW ...... 3-17 3-8 Abundance versus Time for Gigartino papillato at +3 ft MLLW ..... 3-18 3-9 Abundonce versus Time for Iridaea flaccida at +1 ft MLLW . .. . .... 3-20
' 3-10 Abundance versus Time for Iridaea flaccida at +3 f t MLLW . . . . . . . . 3-21 3-ll Abundance versus Time for Anthopleuro elegantissima 4 a t + 1 f t MLLW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3-12 Abundance versus Time for Anthopleuro elegantissima a t + 3 f t M LLW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 3-!3 Abundence versus Time for Haliotis crocherodii at +1 ft MLLW .... 3-32 3-14 Abundance versus Time for Haliotis crocherodii at +3 ft MLLW .... 3-33 3-15 Abundance versus Time for Collisello scabra at +1 ft MLLW ....... 3-37 3-16 Abundance versus Time for Collisello scabra at +3 ft MLLW ....... 3 '
3- 17 Abundance versus Time for Pogurus spp. at +1 f t MLLW . . . . . . . . . . . 3-45 3- 18 Abundance versus Time fc Pogurus spp. ot +3 f t MLLW . . . . . . . . . . . 3-44 3-19 Abundance versus Time for Tegula funebralis at +1 ft MLLW ...... 3-47 3-20 Abundance versus Time for Tegulo funebralis at +3 ft MLLW ...... 3-48 B-82-408 iv
LIST OF FIGURES b (continued)
Figure Page 3-21 Bimonthly Catch Per Unit Effort (CPUE) from August 1976 to April 1981 ............................... 3-61 3-22 Size Frequency Distributin for 5021 Male and 3668 Female C_. antennarius captured in 5mm width increments . . . . . . . . . . . . . . . . 3-62 3-23 Sebastes mystinus, Blue Rockfish ............................. 3-73 3-24 Sebastes serranoides/flavidus ................................ 3-77 3-25 Sebastes chrysomelos, Black and Yellow Rockfish ............... 3-80 3-26 Sebastes paucispinus, Bococcio ............................... 3-82 3-27 Oxylebius pictus, Pointed Greenling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-85 3-28 Sebastes rostrelliger, Grass Rockfish . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-88 3-29 Embiotoca lateralis, Striped Surfperch . . . . . . . . . . . . . . . . . . . . . . . . . . 3-91 3-30 Embiotoca locksoni, Black Surfperch . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-94 3-31 Scorpoenichthys mormoratus, Cabezon ......................... 3-97 3-32 Subtidal Weekly Mean Temperature in North Diablo Cove from July 1976 to February 1980 ............................. 3-int V 3-33 Weekly Average Water Temperatures for Stations 8-10,12-10, 12+12 (Subtidal and Intertidal 1980- 1982) . . . . . . . . . . . . . . . . . . . . . . 3- 102 3-34 Diurnal Temperature Record Diablo Cove Station 12-10 (-3.05 m), May 6-9,1978 . . . . . . . . . . . . . 3-104 3-35 Temperature Record for Intertidal Station 12+2 South Diablo Cove, December 8-9, 1978 . . . . . . . . . . . . . . . . . . . . . . . 3- 105 3-36 Diablo Cove incident (Solid Line) and Underwater (Doshed Line -
10 FT MLLW) Hourly Mean Light Values, January, February, and March, 1981 and 1982 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1- 108 3-37 Diablo Cove incident (Solid Line) and Underwater (Doshed Line -
10 FT MLLW) Heurly Mean Light Values, April, May and June, 1981 and 198 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 109 B-82-408 v
'l LIST OF FIGURES (continued)
Figure Page 3-38 Diablo Cove incident (Solid Line) and Underwater (Doshed Line -
10 FT MLLW) Hourly Mean Light Values, July, August and September, 1981 and 1982 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 1 10 3-39 Diablo Cove incident (Solid Line) and Underwater (Dashed Line -
1 10 FT MLLW) Hourly Mean Light Values, October, November l
and December, 1981 and 1982 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 1 1 I 4 3-40 Subtidal Mean Hourly Photosynthetically Active Solar Irradiance, May 1982, North and South Diablo Cove .... ................. 3-113 I
3-41 Wave Data (Maximum, Average and Significant Wave Height j and Wave Frequency) Recorded for 1981 ....................... 3-11S 3-42 Wave Data (Maximum, Average and Significant Wave Height and Wave Frequency) Recorded for 1982 ....................... 3-116 O
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O LIST OF TABLES Table P_oge 3-1 Summary of Completed TEMP Intertidal Sampling:
+l.0 Foot (MLLW) ........................................... 3-2 3-2 Summary of Completed TEMP Intertidal Sampling:
+3.0 Foot (MLLW) ........................................... 3-4 3-3 Monthly Sampling Occurrences for the Bond Transect Method by Station / Level ..................................... 3-6 3-4 Abundance of Anthopleuro elegantissimo at Two Levels on Five Stations in Surveys 3 to 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 3-5 Abundance of Holiotis crocherodii at Two Levels on Five Stations in Surveys I to 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-34 3-6 Abundance of Collisella scabra at Two Levels on Five Stations in Surveys 3 to 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40 fs 3-7 Abundance of Pogurus spp. at Two Levels on Five Stations in Surveys 3 to 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-45 (J) 3-8 Abundance of Tegulo funebralis at Two Levels on Five Stations in Surveys 3 to 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-49 3-9 Monthly Sampling Occurrences for the Rondom Point Contact Method for Eoch +l.0 and +3.0 Ft MLLW Quadrat by Station . . . . . . . 3-52 3-10 Summary of Completed intertidal Algol Scroping/ Biomass Program +2.0 Foot (MLLW) ................................... 3-54 3-11 Summary of Completed Intertidal Black Abalone Tagging Surveys .. 3-55 3-12 Summary of Completed Subtidal TEMP Sampling . . . . . . . . . . . . . . . . . 3-57 3-13 Total Number of Concer antennarius Captured, and Overall Catch per Unit Effort (CPUE) for Surveys 20 through 34 . . . . . . . . . . 3-58 3-14 Summary of Completed TEMP Subtidal Settling Plate Surveys ..... 3-99 4-1 Species included in 1982 Heat Treatment Thermal Effects Experiments ................................. 4-4 v
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TFERMAL EFFECTS MONITORING PROGRAM AbNUAL REPORT FOR 1982 EXECUTIVE
SUMMARY
The results of the Thermal Effects Monitoring Program (TEMP) for the Diablo Canyon Power Plant are summarized and reported for the period January to December 1982. A brief review of activities and data obtained since program inception (1976) is included as background information. The monitoring program currently includes 15 biological and oceanographic study subtasks. The status of all subtasks is briefly described and analysis of data from six subtasks is reported in detail. The detailed reports include the results from the intertidal band transect studies of algol and invertebrate populations, subtidal rock crab tropping or.d togging studies, subtidal fish observation transects, and in situ light, temperature, and wave recordings. The results reported in the 1982 annual report continue to add to the description of the existing baseline conditions of the expected receiving waters of the power picnt's cooling water discharge.
Population trends established by these studies will enable on assessment of the effects of the thermal discharge following the startup of the power plant which is anticipated to occur in mid-1983.
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1.0 INTRODUCTION
The 1982 Thermal Effects Monitoring Program (TEMP) report is submitted in accordance with the Monitoring and Reporting requirements of the NPDES Permit issued by the California Water Quality Control Board, Centrol Coast Region (hereafter referred to as the " Board") for the operation of the circulating water system waste discharge of the Diablo Canyon Power Plant (order number 82-24 as amended in June 1982). As required, on annual report summarizing the results of the Thermal Effects Monitoring Program of the cooling water discharge shall be submitted to the Board by January 30 of each year.
Since the power plant did not operate in 1982, there were no thermal effects related to the cooling water discharge. This report summarizes the methods and the status of 15 TEMP subtasks (individual sampling and data recording activi-ties) and examines in detail the sampling results of selected subtasks. The majority of these subtasks have been performed routinely (with some modifico-s tions to their methods and scope) since 1976 when they were designed and implemented under the 316(a) Demonstration Program.
Following the reissuance of the NPDES permit in January of 1982, the thermal effects monitoring efforts were reviewed and included under the permit's thermal effects monitoring requirements. However, the objectives of the original monitoring program remained unchanged and the subtasks of the initial program are being continued.
The TEMP field studies are designed to yield on extensive data base on the spatial distribution of the major populations of marine floro and founo in Diablo Cove and the surrounding areas that will enable comparative evaluations of the effects of the thermal discharge on these species. Intertidal and subtidal algal, invertebrate, and fish abundances have been quantitatively monitored at regular sampling intervals since 1976. Fixed sampling is conducted at precisely located sampling stations in Diablo Cove and in reference areas to the north and south of the Cove. Certain laboratory tasks (biomass determinations, settling plate analyses and species identifications) are also performed in support of the field B-82-408 l-l L
O studies. Water temperatures, incident and transmitted light, weather, tides, current, and wave conditions are also being recorded.
The TEMP also included a major series of laboratory studies on the thermal tolerances of important species of the Diablo Cove region. The results of these studies, which were completed in 1982, have been published and will be submitted to the Board in a separate report titled " Compendium of Thermal Effects Laboratory Studies" in January 1983. The results of recently completed laboraiory studies of short-term high temperature tolerance tests will be added to the compendium report as on addendum os discussed in SECTION 4.0.
This 1982 annual report is the seventh in the series of progress reports to the Board which includes reports dated December 1976, October 1977, May 1978, February 1979, November 1979 and August 1980. In addition to the regular progress reports, a report was recently prepared at the request of the Board which summarized the field and thermal effects laboratory studies in on assessment of the potential thermal effects of the DCPP discharge. The report N
titled " Thermal Discharge Assessment Report - Diablo Canyon Power Plant" was submitted to the Board in April 1982.
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y 2.0 MONITORING PROGRAM METHODS Brief descriptions of the methods employed in gathering biological and physical data for TEMP are included in this section. For purposes of clarity, the methods have been broken down into 15 subtasks, each of which is described separately.
2.1 INTERTIDAL BAND TRANSECT The abundance of algoe and invertebrates is monitored bimonthly at fixed intertidal stations of two levels (+l and +3 ft MLLW) within fixed 30 m x 1 m bonds (FIGURE 2-l). Currently,10 fixed quadrats per station level are sompted.
In addition, five of these quadrats ("Tequia quadrats") are more intensively sampled for all macroinvertebrates.
l The five "Tequlo quadrots" on each band transect are surveyed on a bimonthly basis. Abundance estimates of algae and encrusting invertebrates are obtained by using o i m2 quadrat that is subdivided into 16 blocks; each of which can be subdivided into nine smaller blocks. The quadrat is clipped to a transect line strung along the station level. Percentage cover estimates are obtained by recording the number of squares (either 1/16 or 1/144) occupied by a particular taxon. Intensive macroinvertebrate estimates are made on the five "Tequia quadrats"(FIGURE 2-2). These quadrats are searched from all angles'of view for macroinvertebrates. All macroinvertebrate taxa observed are counted and recorded for each quadrat.
2.2 INTERTIDAL 0.25 m2 RANDOM POINT CONTACT QUADRAT (RPCO) l l
A random point contact method is used to measure percentage frequency of oc-currence os on index of percentage area covered by dominant intertidal algae.
Algal area cover is monitored at bimonthly intervals within fixed horizontal 0.25 m2 quadrats located approximately in the middle and at either end of the fixed 30 m x 1 m band transect (FIGURE 2-2). Occuponey of primary, secondary and higher order space is considered as well as the presence of biologically B-82-408 2-1 l
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FIGURE 2-1 20-20 INTERTIDAL AND SUBTIDAL BIOLOGICAL SAMPLING AND STATION LOCATIONS
O O O 93 OFFSHORE
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I ITI I III61 P-i +3.0 c ,__" e A l ONSHORE I O- Fixed Stenderd Quadrag --- Algol Seraping Band
( n = 10 per bend ) l o Rendem Algee Seroplag Goodret E -Fixed"Togule"/ Standard Quadrat Stellen Origin Pfete ( O.OS25 snt n=3 per bend )
(n= 5 per bend) 1 1 Reference Stelles 0 -Flued Random Peint Centact (n= 3 per band ) i hides
.O-FIGURE 2-2 HYPOTHETICAL INTERTIDAL STATION I
unoccupied space. Data on canopy structure are collected by coding the level of contact.
The 0.25 m2 random point contact quadrat censists of a metal square,'0.5 m on a side, and a metal crossbar which slides across the metal frame. Alignment of the quadrat on the site is accomplished with a series of removable truing pins set in epoxy plastic pods offixed to rock substrate. Each of two parallel sides of the metal square, and the crossbar, are scribed into 20 equal units. Paired coordinate numbers ranging from 0 to 20 are used to determine the position of contact points. For each survey a series of 60 randomly generated point contacts constitute the data used to calculate frequency of ocevrrence. All algae occurring at each selected point are recorded with numbers. The number
- assigned to each alga corresponds to the order in which it was contacted as the l observer proceeds from surface layer to substrate at each point.
2.3 INTERTIDAL ALGAL SCRAPINGS Algol scrapings are collected biannually from 25 randomly positioned 0.06 m2 quadrats of permanent stations located near existing intertidal band transects
("AS" stations in FIGURE 2-lh in each sample, percentage cover estimates are obtained for all attached algae and encrusting invertebrates. Additionally, the
- numbers of individuals of motile invertebrate species encountered are recorded.
All attached algoe are then removed using a metal scraper, placed in a labeled plastic bog and returned to the laboratory for processing, or are frozen to await processing.
Laboratory treatment of each sample consists of sorting all algoe into specific taxa. Iridaea floccido, a very common foliose red algo, is further subdivided into
-life-history stages (juveniles; immature males, females and tetrosporophytes; mature females; mature tetrosporophytes). Blade counts and blade lengths are then obtained for each life stage. Each of these sorted life-history categories, along with the remaining sorted taxo in the sample, are placed in separate glass dishes and dried for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 100 C (212 F). Dry weight measurements are then recorded for all sorted specimens.
B-82-408 2-4
2.4 INTERTIDAL BLACK ABALONE TAGGING l Black abalone are individually tagged, measured and remeasured to estimate and compare overage growth rates of populations in four areas in the Diablo Canyon study area. During each abalone survey, abalone found within 'I x 30 m band transects at +1 ond +3 tide level, and which could be assessed without damage, are measured and tagged with numbered stainless steel wire togs and cemented disc togs. On subsequent surveys, accessible tagged abalone are remeasured and positions along the transect noted. In addition, the precision of the measurement technique and tog losses are estimated during selected surveys. .
4 The location of all tagged individuals is recorded as linear distance and compass direction from o permanent relocatable marker. Measurement of abalone consists of determining the longest shell dimension with a pair of machinists' calipers and comparing that distance to a metric ruler, recording length to the nearest millimeter. Precision estimates of the measurement technique are obtained by measuring the same abalone five times using five independent observers. Additional precision estimates are obtained by repeating the same procedure in the laboratory using empty abalone shells.
2.5 DIABLO COVE BLACK ABALONE 3URVEY The purpose of this study is to determine os accurately as possible the number and distribution of block obalone, Haliotis crocherodii, within Diablo Cove. A randomly placed quadrat method is utilized. Beginning near the discharge and running to the south and to the north, Diablo Cove was divided into segments 100 m long. A stake positioned near the discharge structure served as the origin for each area. A 100-m line marked off in I-meter segments was run along the intertidal zone at on elevation of opproximately +2 MLLW. In practice, the line followed the middle of the Iridaea flaccida zone. At any inflection point along the line, o stake or on already established intertidal monument was used to mark the point of inflection. Distance and bearing (using a hand bearing compass) l from the origin to an inflection point or from inflection point to inflection point were noted. The end of one 100-m section served as the origin for the next
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B-82-408 2-5 l
{V\
Six sections were established in both the north and south areas of Diablo Cove in such a way that each section could be relocated with reasonable precision.
Using the transect line as a reference point, the area between the estimated 0.0 and +4 ft tide levels was delimited. These levels were generally defined as the upper limit of Phyllospadix spp. and the upper limit of Pelvetic fastigiata, respectively. The area thus delimited was considered to be the zone in which most intertidal black abalone occur. Due to the variable nature of the intertidal zone, each 100-m section was irregularly shaped.
The total number of square meters encompassed in each section was calculated graphically. It was decided that 10 percent of the area in each section would be a suitable sample. Therefore, each potential 1-m2 site within the section was numbered and random numbers were generated so that 10 percent of the potential sites within a section would be selected on a random basis. The site locations were transferred from these maps to a master dato sheet listing the section number (NDC 1-5 or SDC l-6), the ordinnte (1-100 m), and the location y of the quadrat to be sampled as onshore (+) or offshore (-).
The field team consists of one recorder and four observers. At each sample locus the following dato are collected:
l o Substrat type (boulder, cobble, sand, or bench rock) o Amount of relief (low, less than 30 cm; medium, l
30-70 cm; high, over 70 cm) o Dominant algae o Total number of abalone.
l 2.6 INTERTIDAL STATION PHOTOGRAPHY SUBTASK The intertidal photography survey consists of taking color Ektochrome and infrared photographs of intertidal stations. The general creo (" cliff top")
photographs are taken at each fixed station within each of the seven major B-82-408 2-6
r-~
s intertidal areas in the Diablo Canyon study site. All intertidal random point contact quadrats (RPCO) are individually photographed.
The photographs from these surveys will be used to document changes in (l)overall area covered by algae within fixed quadrats during comparable seasonal periods, (2) the proportion of green, brown and red algoa, and (3) algal health (bleaching, etc.) condition.
2.7 SUBTIDAL ARC QUADRANT PROCEDURE:
MACROALGA AND MACROINVERTEBRATE COUNTS Each permanent subtidal station at Diablo Canyon is circular, approximately 28 square meters in area, and is divided into four equal pie-shaped sections or ore-quadrants of 7.5 m2 area (FIGURES 2-1 and 2-3). A railroad wheel reorks the center of the station. The purpose of this sampling method is to determine the species composition, and the population densities of the more conspicuous, representative, and countable subtidal biota. The number of individuals of each species present in each of the quadrants is recorded. The data from the four O orc-quadrants will be used to determine spatial variability within the station.
Taxo to be considered by the arc-quadrant method include (1) the larger motile
! (nonencrusting and nonhabitat forming) benthic invertebrates for which indi-vidual count data can be made, and (2) several species of the larger (conopy) algae for which point contact estimates of percentage cover (see RLPC methods, SECTION 2.9) are impractical. These algal taxa include Pterygoohora califor-nica, Laminoria dentigero, Cystoseiro osmundacea, Nereocystis luetkeana, and Egregio menziesii. The invertebrate taxa include all individuals of those taxo printed on the data sheets (Form No. 07); for those taxo not printed on the data sheets and which satisfy the above requirements, only those individuals greater than I in. long are counted. In addition, the abundant invertebrate taxa Acmaea mitro, Tonicella lineata, Colliostoma ligatum, Tegula brunnea and Tequia montereyi are counted only in the first one-third of each arc-quadrant. The density of each species per ore-quadrant is then extrapolated from this sub-sample.
i B-82-408 2-7
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l l DIAGRAM OF SUBTIDAL SAMPLING STATION i
O B-82-408 2-8
A 2.8 SUBTIDAL FlXED CIRCULAR QUADRAT PROCEDURE:
INVERTEBRATE SAMPLING Fixed location quadrots are monitored at each subtidal station to determine the species composition and population densities of the smaller, more cryptic subtidal invertebrates, including " habitat-formers," not quantified by the arc-quadrant count (SECTION 2.7) or the rondom line point contact methods (SECTION 2.9). Four circular quadrats with an area of 0.25 m2 are sampled at each station. Quadrat locations were selected on the basis of physical criteria including uniform hard substrate, with two quadrats at a given station lying nearly hori'.ontally and two quadrats lying more nearly vertically, and on the biological criteria that locations be representative of the arc-quadrant's domi-nont microfounal assemblages. There is no maximum size limit for the invertebrate taxa in these quadrats; minimum size limits are fixed by visual discernobility. Habitat-forming and encrusting forms are quantified by the number of square cm they cover; individuals of all other taxa are counted.
2.9 SUBTIDAL RANDOM LINE POINT CONTACT (RLPC) d A random line point contact (RLPC) method is used to document the percentage crea covered by habitat-formers; i.e., all macroscopic occupants of substrate within the 30 m2 subtidal stations. Although habitat-formers con be either encrusting invertebrates or algae, the predominant habitat-formers on the TEMP subtidal stations are algae and this procedure was developed primorly to quantify algae abundances.
An equal number of points are sampled within each of the four quadrants so that four statistical replicates are obtained. A weighted line with one end attached to e pin (on the railroad wheel marking the center of each subtidal station) and the other end free is used to located the sampling loci. The line has 10 points marked by small lead weights numbered 0 to 9; their position along the line is graded, with point density increasing toward the station perimeter to counteract the " center bios" introduced by the distribution of points on a radius within a circular orco. Of 100 possible sampling loci created by positioning the weight
\
B-82-408 2-9
s line at 10 equidistant locations across the quadrant, 50 points in each quadrant are randomly selected and their location is printed on the RLPC data sheet (Form 10, Rev. C). A total of 200 points is sampled in survey. Sampling loci are changed for each bimonthly subtidal survey.
The dato collected consists of noting what lies immediately over the loci to be sampled and the type of substrate or encrusting invertebrate lying immediately under the loci.
2.10 SUBTIDAL CRAB TRAPPING AND TAGGING A series of standard commercial " Igloo" crab traps are fished at subtidal stations (FIGURE 2-4). Weather permitting, the trop set program devised for each survey requires approximately seven consecutive days. Each of the trop set locations is fished for a 2413 hour0.0279 days <br />0.67 hours <br />0.00399 weeks <br />9.181465e-4 months <br /> period.
Upon retrieval of each trop, the following data are recorded: trop set location, caropoce measurement of individuals, determination of the sex and reproductive d condition of females (berried vs. non-berried), and molt or intermoit condition of crabs of both sexes. Afterwards, specimens of Cancer antennarius or: togged using a "Floy" onchor tog and are released in the immediate vicinity of capture.
A " claw index" based on the presence or obsence and/or size of the chelipeds is recorded for each individual.
Seasonal differences in growth, mortality, migration, and population densities are obtained for these species as a result of these detailed tagging and recapture l
methods.
l l
2.11 FISH OBSERVATIONS SCUBA observations of fish at fixed subtidal transects contribute to the l
documentation of the subtidal fish assemblages of the Diablo Canyon area.
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20-20 21-25 FIGURE 2-4 TRAppggG STATION 6
Visual observations are made along transects (FIGURE 2-5) during midday hours (0900-1500). Both vertical transects (ocross depth contours) and horizontal transects (along selected isoboths) are sampled. The vertical transects are positioned between the fixed -10 ft and -15 ft (MLLW) station monuments which are centrally located within each study creo. These transects provide documen-totion of species composition and abundance at different depths within on oreo.
The horizontal transects extend along the -10 f t and -15 ft isoboths within each crea to document species composition and abundance at selected depths. The transects are " fixed" along predetermined compass bearings.
All transects have a fixed length (50 m) and a fixed width (2 m) on either side of the diver. A fixed minimum belt width of 2 m ovoids the necessity of normoli-zing the data taken by a " visual oculty side transect" method. A two-meter distance was judged to be the minimum required for odequate fish observations.
Therefore, transects are performed only under conditions of at least 2 m lateral visibility.
Each station is replicated once within each survey. Water temperature and lateral visibility are measured at each end point of a transect by both benthic.
and midwater observers.
2.12 SETTLING PLATE j Subtidal settling plates installed at the shallow subtidal (-10 f t MLLW) stations provide information on the species composition, abundance, distribution and biomass of founo and floro that initiate biological processes and participate in community development on newly exposed substrates.
At each station wheel, six vertically-oriented osbestos plates (25.3 x 25.3 x 0.7 cm) are ottoched parallel to each other in a stainless steel rock. All plates l
ore presoaked in freshwater for 30 days to leach out toxic substances. Each rock is oriented so that its plates are positioned perpendicular to the incoming wave fronts. Two nylon electrical ties attached to one end of the rock identify the p lef t end of the rock facing onshore. Side A of each plate faces lef t (toward the I
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O V ties) while side B faces right. The plates are numbered I through 6 from left to right, and plates are sequentially replaced every two months.
In. July of each year, all plates are replaced and new plates are installed (see FIGURE 2-6). Every two months, certain plates are removed from the rock, insuring the identification of sides A and B, and are placed in individual buckets, and transported to the laboratory for analysis. A new plate is installed whenever o plate is removed.
In the laboratory, each side of the plate is photographed using Kodak Ekto-chrome-X color transparency film. A list is made of all taxa found on the plate edae and the outermost 2.6 cm of the plate. Any alga over 2.6 cm in length that could possibly offect settlement by sweeping spores and larvae off the plate is categorized as a " sweeper." The length of the longest individual of each sweeper species is measured and recorded. Edges and margins are then scraped clean of remaining material and another photograph taken of each side of every plate.
Using a seawater-filled chamber with a fixed grid system, on investigator pre-cisely locates random sampling points on the settling plate face. The plate face is designated as that port of the plate located inside of the scraped margin area.
Because of the vertical orientation of the plates in the rock, it seemed likely that differential settlement of algae and invertebrates would occur on the plates due to the varying light levels striking the plate surface. For this reason, the plate foce is divided into three equal sections (band levels) resulting in stratified sample dato collection.
To determine the abundance of taxo found on the plate face, two methods are used: (1) random point contact (RPC) for the macroscopic habitat formers, and (2) random 9 cm2 quadrats for the microscopic habitat-formers (individuals less than 2 mm in size). For each band level,100 RPC points and five quadrats were sampled, determined by randomly selected X and Y coordinates. For the RPC method, o vertical line is possed through each coordinate and all intercepted
" contacts" are recorded. The quadrat method provides a visual estimate of the
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B-82-408 2-14
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SEQUENCE OF SETTLING PLATE INSTALLATION AND REPLACEMENT B-82-408 2-15 ,
b percentage cover of all individuals less than 2 mm in size. Frequency was J recorded as being in one of the following cctegories: 1 (+ to 1%), 2 (l+ to 5%), 3 (5+ to 20%), 4 (20+ to 50%), 5 (50+ to 75%), or 6 (75+ to 100%). The above procedures are used for the plate faces on both sides A and B.
Upon completion of the above sampling procedures, the plate is removed from the counting chambers, potted dry, and each band level scraped clean with the residue weighed to determine wet weight biomass. Dry weight biomass is then determined offer oven drying at 100 C (212F ) for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
2.13 IN SITU TEMPERATURE Digital dato recording temperature monitors are placed at +2 ft (MLLW) at intertidal stations (FIGURE 2-7). Each thermistor records temperature through-out the year at 20-minute intervals at its assigned location. The physical dato obtained supplements the biological information derived from the intertidal i
studies. A monthly service schedule during low tides provides for replacement of s batteries, exchange of new cassette tapes for recorded ones, and repair of faulty instruments when needed.
Digital dato recording temperature monitors are also placed at -10 ft (MLLW) subtidal stations. Each thermistor records temperature throughout the year at 20-minute intervals at their assigned location. The physical data obtained supplements the biological information derived from the subtidal studies.
SCUBA divers replace batteries, cassette tapes, and check the instruments on a monthly basis.
2.14 IN SITU LIGHT Digital dato recording light monitors (Model TLR-l) are placed at subtidal l stations 7-10 and 11-10 (FlGURE 2-7). Each unit records transmitted light values throughout the year at 20-minute intervals. The instrument is serviced on a weekly basis.
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l A land based Solar irradiance Monitoring System (SIMS) is maintained on the cliff top approximately 600 ft southeast of the meteorological tower. Total and instantoneous light values are recorded at 5-minute intervals.
- 2.15 IN SITU WAVE / TIDE SUBTASK Digital pressure (tide) recording system (TDR) is installed at subtidal station 9-10 (FIGURE 2-7). The unit will record tide level throughout the year at 20-minute intervals. The instrument will be maintained monthly.
1 A digital wave monitoring system (TWR) is installed at the 100-f t (30 m) contour in a location opproximately 2500 ft (760 m) south-southeast from the point of discharge.
t l
B-82-408 2-l8 l
l 1-t
3.0 MONITORING PROGRAM RESULTS Results of the 1982 field sampling studies are presented in this section. Because the lost report (l'GandE 1980) covered sampling activities up to August 1980, this chopter also documents results obtained since that time.
Among the intertidal subtasks, two new band transect stations have been added (stations 22 and 23, see FIGURE 2-1) and three band transect stations that were sampled only very early in the prog.am (stations 7,10 and 15, see FIGURE 2-1) were reactivated. A new intertidal subtask, black abalone survey, was initiated.
Among the subtidal tasks, a new station (Station 13-32, see FIGURE 2-1) was added.
3.1 INTERTIDAL BAND TRANSECT (!BT)
Six intertidal band transect (IBT) surveys were completed in 1982 (TABLES 3-1, O 3-2, 3-3). In the following sections, analyses of the Diablo Cove stations IBT U data on five algal and five invertebrate species are presented, documenting the changes in species populations from 1976 to 1982.
3.1.1 ALGAE A major portion of the TEMP intertidal effort consists of sampling band j transects permanently located in Diablo Cove and surrounding areas. This section includes on analysis of the dato collected on five algal species in 1.0 m2 quadmts which make up the band transects. These species are Endocladia muricato, Gastroclonium coulteri, Gigartina conoliculata, G_. papillata and Iridaea floccido. Earlier progress reports (LCMR 1978, PGandE 1978) presented preliminary evaluations of the abundance of the major algal species within TEMP's band transects for the first year sampling effort (surveys 01 to 07).
Algol percentage cover summaries for this one-year period (April 1976 to May 1977) indicated that 1. flaccida, G. canaliculata, and G_. coulteri were among the 10 most abundant species at the majority of low elevation (+1.0 ft MLLW) study B-82-408 3-l
O O U V TABLE 3-1 J
i
SUMMARY
OF COMPLETED TEMP INTERTIDAL SAMPLING: +l.0 FOOT (MLLW)
Algae Invertebrates
{
I Bond Point Algol Std. Inverts. " Precise"
,'T@o
Survey Date Transect Contact Scroping Count Count Na, No. No. No. No. No. No. No. No. No. No. No.
Stations Quadrats Stati<w Ovodrots Stations Quodrats Stations Quodrots Stations Quadrats Stations Quadrots Of April 1976 15 450 16 48 15 45 15 375 0 0 15 75
- 02 June 1976 15 450 16 48 15 45 15 375 0 0 15 75 03 August 1976 15 225 16 48 15 45 15 150 15 75 15 75 04 October 1976 15 225 16 48 15 45 15 150 15 75 15 75 05 December 1976 15 225 16 48 15 45 15 150 15 75 15 75 06 February 1977 15 225 16 48 15 45 15 150 15 75 IS 75 07 May 1977 15 225 16 48 15 45 15 150 15 75 - 15 75 08 June 1977 7 105 8 24 7 21 7 70 7 35 7 35 i
w 09 July 1977 7 105 8 24 - 7 21 7 70 7 35 7 35 k 10 November 1977 7 105 8 24 . 7 21 7 70 7 35 7 35 I il December 1977 7* 105 .7* 21 0 0 7 70 0 0 7 35 12 February 1978 7 104 7 21 0 0 7 70 1 5 7 34 13 April 1978 9 135 10 30 0 0 9 90 1 5 9 45-14 June 1978 9 135 10 30 0 0 9 90 1 5 9 45 15 August 1978 9 135 10 30 0 0 9 90 1 5 9 45 16 October 1978 9 129 10 28 0 0 9 86' I 5 9 43 l 17 December 1978 9 135 'O 30 0 0 9 90 1 5 -9 45 18 February 1979 9' 135 10 28 0 0 9 90 I $ 9 45 19 April 1979 9 135 10 30 0 0 9 90 1 5 9 45 20 June 1979 9 135 10 30 0 0 9 90 1 5 9 45 21 August 1979 9 135 10 30 ** 9 90 1 5 9 45 22 October 1979 8 105 9 27 7 65 1 5 8 40 23 December 1979 9 135 10 30 9 90 1 5 9 45 24 February 1980 5 66 6 16 5 42 i $ $ 74 25 April 1980 9 90 10 30 9 45 1 5 9 65 26 June 1980 9 90 10 30 9 45 I 5 9 45 27 August 1980 - 9 90 10 ' 30 9 45 1 5 9 45 4
28 October 1980 9 90 9 27 9 45 1 5 9 45 29 December 1980 9 90 10 30 9 45 1 5 9 45 30 Febroory 1981 9 90 10 30 9 45 1 5 9 45
- Two stations outside of work plan were so wied.
- New subtask, see TABLE 3-10.
B-82-408
l TABLE 3-1
SUMMARY
OF COMPLETED TEMP INTERTIDAL SAMPLING: +l.0 FOOT (MLLW)
(CONTINUED) i i
i Algae Invertebrates Band Point Algal Std. Inveris. Precise" Survey Date Transect Contact Scraping Count Count T*la" No. No. No. No. No. No. No. No. No. No. No.
- No.
Stations Quadrats Stations Quadrots Stations Ovadrats Stations Quadrats Stations Ovadrats Stations Quadrats I
31 April 1981 9 90 10 30 ** 9 45
- 1 5 9 45 32 June 1981 9 70 10 30 9 45 5 1 9 45
- 33 August 1981 9 90 10 30 9 45 1 5 9 45
, 34 October 198I 9 90 10 30 9 45 l 9 5 45 35 Decernber 1981 9 90 10 30 9 45 1 5 9 45 36 Febru sy 1982 9 90 10 30 9 45 5 9 37 April 1982 1 45 11 110 12 36 11 55 l 5 W 38 Il 55 June 1982 ll 110 12 36 55 11 1 5 11 55 L 39 40 Octooer 1982 August 1982 ll 6
110 12 36 ll 55 1 5 11 55 .
60 11 32 6 30 t 5 6 30 41 December 1982 9 90 9 27 9 45 9 1 5 45
- New subtask, see TABLE 3-10.
4 4
B-82-408
\
T ABLE 3-2 ~
SUMMARY
OF COMPLETED TEMP INTERTIDAL SAMPLING: +3.0 FOOT (MLLW)
~
Algoe Invertebrates I Bond Point Algol Std. Inverts. " Precise" i Survey Date Transect Contact Scraping Count Count "T %
I No. No. No. No. No. No. No. No. No. No. No. No.
Stations Quadrots Stations Quadrots Stations Quadrats Stations Quodrats Stations Quadrats Stations Quadrots 01 April 1976 19 570 21 '61 18 54 19 400 0 0 02 18 90 June 1976 19 570 21 61 18 54 19 480 0 03 August 1976 0' 18 90 19 285 21 61 18 54 _19 195 18 90 18 90 04 October 1976 19 285 21 61 18 54 19 (95 18 90 18 90 05 December 1976 19 285 21 61 18 54 19 195 16 90 18 90
.06 Febroory 1977 19 285 21 61 18 54 19 195 IR 90 18 90 07 May 1977 19 285 21 61 18 54 19 195 la 90 18 90 08 June 1977 0 0 4- 12 0 0 0 0 0 0 0. O
! 09 July 1977 9 135 9 ,27 0 0 9 90 9 45 9 45 10 November 1977 0 0 4 12 0 0 0 0 0 0 0 0 7
ll December 1977 7' 105 7' 19 0 0 7 75 0 0 6 30 12 February 1978 7 105 8 22 0 0 7 75 i 5 6 13 April 1978 30 10 150 10 28 0 0 10 105 1 5 9 45 14 June 1978 10 150 10 28 0 0 10 105 1 5 9 45 15 August 1978 10 150 10 28 -0 0 10 105 5 9 1 45 i
16 October 1978 10 150 10 28 0 0 10- 105 1 5 9 45 l 17 December 1978 10 150 10 28 0 0 10 105 1 5 9 45 i 18 February 1979 10 ISO 10 28 0 0 10 105 1 5 9 45
- 19 April 1979 10 150 10 28 0 0 10 105 5 9 1 45 20 June 1979 10 150 10 28 0 0 10 105 1 5 .9 45
! 21 August 1979 10 150 10' 28 ** ' 10 105 1 5 -9 45 22 October 1979 10 140 10 28 9 95 1 5 9 45 23 December 1979 . 10 150 10 28 10 105 1 5 9 45 24 February 1980 7 105 7 19 25 April 1980 7 75 l 5 6 30 ~
10 100 10 28 10 55-1 5 9 45 26 June 1980 10 100 10 28 10 55 1 5 9 45 27 August 1980 10 100 10 28 10 55 l 5 9 45 28 October 1980 10 100 10 28 10 55 1 5 9 45 29 December 1980 10 100 10 28 to : 55' I 5' 9 45 l
30 February 1981 10 100 10 28 10 55 9 I 5 45
- Two stations outside of woric plan were sampled.-
! " New subtask, see TABLE 3-10.
B-82-400 l .
("'
f
. TABLE 3-2
SUMMARY
OF COMPLETED TEMP INTERTIDAL SAMPLING: +3.0 FOOT (MLLW)
(CONTINUED)
Algoe Invertebrotes Band Point - Algol Std. Inverts. " Precise"
Tylo" Survey Date Transect Contact Scroping Count Count No. No. No. No. No. No. No. No. No. No. No. No.
Stations Quadrats Stations Goodrots Stations Quadrots Stations Quadrots Stations Quadrots Stations Quadrots' 31 April 1981 10 100 10 28 ** 10 55 1 5 9 45 32 June 1981 10 100 -10 28 10 55 1 5 9 45 33 August 1981 10 100 10 28 10 55 1 5 9 45 34 October 1981 10 100 10 .28 10 55 1 5 9 45 35 December 1981 10 100 10 28 10 55 1 5 9 45 j 36 February 1982 10 100 10 28 10 55 1 5 9 45 .,
37 April 1982 14 140 14 40 14 75 1 5 13 65 w 38 June 1982 .14 140 ' 14 40 14 75 1 5 13 65 in 39 August 1982 14 140 .14 40 14 75 1 5 13 65 40 October 1982 ll 110 ll 31 11 60 1 5 10 50 41 December 1982 10 100 10 29 10 Si 1 5 9 45
- New subtosk, see TABLE 3-10.
i 4
B-82-408
Y m TABLE 3-3
'M
- MONTHLY SAMPLING OCCURRENCES FOlt THE BAND TRANSECT MFTHOD BY STATION / LEVEL 1976 1977 1978 1979 1980 1981 1982
<a ,S <Tooas,, t 3 f & g 3. 3 3ow2 <& ,S <T U <V t a ,g oow 4 T8au
~ E t <a ,g 4 ?8ou4 - E t a ,g 4? ~60u E t <a ,S4T 60
- 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 141 1+3 - -
2+1 2+3 6+1 6+3 -
7+1 -
, b 7+3 -
! 8+1 -
8+3 -
l 9+1 -
9+3 -
10+1 . -
10+2 ll+1 .
11+3 -
12+l 4
12+3 -
14+3 -
15+3 19+1 19+3 -
20+1 - -
20+3 22+3 -
1 3
sites, whereas _l. floccido, G. papillato, and E. muricato commonly ranked among the 10 most abundant species at high elevation (+3.0 ft MLLW) study sites.
Seasonal variations in abundance for these species, April 1976 to August 1979, were presented by LCMR (1978) and PGondE (1977,1978,1980). Summary
[ statistics for these reports utilized data obtained in 15, Im2 quadrats per band transect. Since the time of the lost report (PGondE 1980), the number. of quadrats sampled per transect has been reduced to 10. This report updates seasonal abundance descriptions for 1. floccido, G. papillato, G. canaliculata,
, G. coulteri, and E. muricato to include dato collected up to October 1982.
Summary statistics for all previous surveys utilizing 15 quadrats per transect have been recalculated using data obtained from the 10 retained quadrats per transect. Thus, this report presents dato collected in the some -10 repetitively sompted quadrats per transect from April 1976 to October 1982 (surveys 01 to 40).
Algol cover for each band transect has been summarized by survey utilizing
, mean percentage cover per square meter values. These values were derived by overaging abundances across all 10 currently sampled quadrats. The mean
- percentage cover values given in this report are from untransformed quadrat percentage cover values.
Data from stations 8, 9, II,12, and 14 were analysed for seasonal variations of the five most obundant species (E. muricota, G. coulteri, G. canaliculato,
~
G_. papillota, l. flaccida) for the period April 1976 to October 1982 (surveys 01 to 40). The results are organized on a species-by-species basis and are presented below.
3.1.1.1 ENDOCLADIA MURICATA j Endocladio muricato is the most common olgo of the upper intertidal in centrol California (Abbott and Hollenberg 1976) including Diablo Cove and vicinity. This i low (4-8 cm toll) densely shrubby oigo forms clumps or mots on the tops and vertical faces of rocks.
B-82-408 3-7
O h Mean percentage cover data for this species are presented in FIGURES 3-1 and 3-2. Because of its high intertidal distribution, this species was nearly locking in most +l.0 ft transects. This was also true for Station 14+3 and to some extent Station Il+3. Seasonal peak obundances in - the remaining +3.0 ft transects generally occurred around spring each year.
According to Cubit (1974), E. muricato is highly susceptible to sand scour during winter.
He first noted sand becoming embedded amongst holdfasts during summer. This is the period when sand normally occumulates on beaches. Basal branches and holdfasts were then presumably deprived of oxygen due to sediment smothering. Later, winter storm activities and shifting sediments removed large clumps of E_. muricota. One con readily see the outcome of these processes in the intertidal when clumps of E. muricata appear in rings. These processes are partially responsible for the seasonal trends observed in the IBT dato.
3.1.1.2 GASTROCLONIUM COULTERI o Literature on Gastroclonium coulteri was reviewed and presented in on earlier report (PGandE 1979). This moderately large, shrubby red algo grows up to 25 cm or more in length. The often densely clumped branches arise from o thick mot-like stolon system which con trap and stabilize sand. In the intertidal region of Diablo Cove and vicinity, G. coulteri is most abundant in the mid to lower zones (Burge and Schultz 1973, LCMR 1978, PGondE 1978).
Mean percentage cover values for this species never exceeded 10 percent in the
+3.0 f t transects; this species was never found at Station 8+3. In the +l.0 f t '
transects G. coulteri never exceeded mean abundances greater than 30 percent.
Annual cycles for _this species were not evident at any of the transects.
Percentage cover data for this species are presented in FIGURES 3-3 and 3-4.
In contrast to the lack of definable trends in the band transects, Burge and Schultz (1973), during earlier studies at Diablo Canyon, reported yearly winter l
low abundances for this species. They attributed the winter low obundances to I be the result of dessication and erosion. Abbott and Hollenberg (1976) also state G B-82-408 3-8
r w
. ,,, , , , , , . . . , , i i . . . . . . i STATION 12 g . -
2 g . -
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ta B
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& STATION 9 e
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JAN JAN JAN JAN JAN JAN JAN 1976 l 5977 8 1978 1 197? I 1980 1 1981 1 1982 I 1983 FIGURE 3-1
, s.
B-82-408 ABUNDANCE VERSUS TIME FOR ENDOCLADIA MURICATA AT +1 FT MLLW 3-9
' ' ' ' ' ' ' ' ' i i i i i i S'TA' TION 14 ' '
s -
R Og -
e ..
O O STATION 12 s -
2-G z 'a -
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$ STATION 11 o 8S -
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e o 5 b d r_ _ s % ,- - ~ ,' -- E O
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3s
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l -s I ,--
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STATIOA 8 S -
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l R -e
/N
_s,'s,. - _ s,_ / - s-s,,___
e i e e a a e i t e e i i t it i e i t i i e o
JAN JAN JAN JAN JAN JAN JAN l 1976 l 1977 1 1978 1 1979 1 1980 1 1981 1 1982 I 1983 FIGURE 3-2 B-82-408 '
ABUNDANCE VERSUS TIME FOR ENDOCLADIA MURICATA AT +3 FT MLLW 3-10
I 1
~l i
1 O
i i i i i i i i i i i i i i i i gg,g ,j i i S -
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J STATION' I I y 9SI
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yS -
R o U T Z %
< W O O Z R -
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's, w-k I STATION 8 9 -
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- l s _,,,,'s_ 4;n-s t
f #
I I e f G I t I I t t l 'I t t t t 3
JAN JAN JAN JAN JAN JAN JAN 1976 1 1971 4 1978 1 1979 1 1980 1 1981 1 1982 a 1983 FIGURE 3-3 i B-82-408 ABUNDANCE VERSUS TIME FOR GASTROCLONIUM COULTERI AT +1 FT MLLW 3-11
STA'TION' 14' 8 ~ -
2 OxJ R - ..
Z J
STATION' 12 9 Z
9S1 R _s b
I t
$R - .
-e - $
8 9 z
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8 .
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& STATION II e s - -
R o w c U g Z w O O Z R - -
2 %
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cc O
\
%/w o o w E ,
STATION 9 s . -
R
~
.e
- o ' i i
- e i -- i 1 - , _ , _, ,a_ _ , _
JAN 1976 1977 1978 197o [980 1981 f" 3987 FIGURE 3-4 B-82-408 ABUNDANCE VERSUS TIME FOR GASTROCLONIUM COULTERI AT +3 FT MLLW 3-12
that plants commonly erode back to basal portions during the winter as a result
^
of dessicotion. However, Gotshall et al. (1978) reported that the dry weight
- biomass of G_. coulteri did not differ oppreciably with season at Diablo Canyon.
3.l.l.3 GIGARTINA CANALICULATA A review of the literature on Gigartino conoliculato was presented in a previous report (PGandE 1979). This species consists of narrow branches arranged in a
" Christmas tree-like" pattern. Abbott and Hollenberg (1976) state that the erect branches of G. canaliculato are annual, .being produced by perennial basal branches. The life history is quite different from that of G. papillata (see SECTION 3.1.l.4) in that the two generations of G. conoliculata are identical in morphology. It is generally distributed somewhat lower in the intertidal than G.
papillata.
Mean percentage cover values for G. canaliculata are presented in FIGURES 3-S
, and 3-6. Seasonal cycles are not as consistently evident across stations for this (v) species compared to Iridaea flaccido and G. popillata (see below). A peak in obundance during the spring-summer period generally occurred from year to year at Station 8+1 and in some years at stations 9+1 and i1+1. Seasonal abundances at each of the other +l.0 and +3.0 ft transects were relatively more stable over i this report period. At Station Il+3, this species occurred only sparsely in a few quadrats and only during a few surveys.
In contrast to the results presented here, Burge and Schultz (1973) working in l similar areas noted that the percentage cover of G. canaliculata, in general, was lower during summer and higher during winter; however, they attributed the summer low obundances to a possible sampling artifact. They stated that the summer maximum cover of overstory species (eg., Iridaea spp.) may have visually obscured and thus created underestimates of the abundar.ce of the shorter i
statured G. canaliculato plants during summer periods. Gotshall et al. (1978) reported that the biomass of G. canaliculato varied little with season during a three-year study summary at Diablo Canyon.
I k
B-82-408 3-13 1 -
~
(
i i i i . . i i .. i i i , i i i i i i .. i i . i STATION 12 S -
R
- o R -
'- ~ ,
w Z -
3 STATION l l y O S -
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9 8
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R o W x T
< ~
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i < o m l w l 2-STATIO$ 8
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,,,ii,ii.'\.'_,__ f\Ii- s , _l s
. . , , I. I i ,
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JAN JAN JAN JAN JAN JAN JAN 1976 -l 1977 1 1978 1 1979 1 1980 1 1981 1 1982 1 1983 O.
FIGURE 3-S B-82-408 ABUNDANCE VERSUS TIME FOR GIGARTINA CANALICULATA AT +1 FT MLLW 3-14 i
4
' ' ' ' ' ' ' ' ' ' ' ' i i i i i STA'TibN Id ' '
S - -R s
v] g . .e o - - o STATION 12 S -
R C
hR -
e f
3 9
_; o O w g o - _ _s _ _-
o O <
= -
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o g -R Z e
cn w 2 2 E L.
8 R -
e O E O.
w C U t Z W
- < o o e U STATION 9 o CD S -
R Z Z M w
2 R -
e
, i' l o STATION 8 s- -
R R -
e o A .a JAN
- m. h t JAN JAf4 JAN JAN JAN JAN i i o 1976 l 1977 1 1978 1 1979 1 1980 1 1981 1 1982 1 1983 FIGURE 3-6 B-82-408 ABUNDANCE VERSUS TIME FOR GlGARTINA CANALICULATA AT +3 FT MLLW 3-15
(
( The cyclical abundance pattern repeated from year to year at Station 8+1 may be related to sand scouring related mortalities. Cursory observations of sand cover dato indicate Station 8+1 contained relatively high proportions of sand. l Furthermore, much of Station 8+1 is situated on a flat rock bench. Plants !
occupying this bench area are more offected by winter storm s and scour than plants living on tops of boulders and rocky outcrops where sand scour is presumably less effective.
Based on existing knowledge, the persistence of G. conoliculato appears to be largely dependent on the survivorship of established adults. In Monterey Bay, California, this species was found to be slow to colonize periodically clected areas (Northeraft 1948). More recently, Murray and Littler (1978) working at Son Clemente Island, California, observed that recruitment of this species did not occur until five months following clearing of plots in December. Further-more, recovery to precleared abundances (25 percent cover) did not occur until 25 months later.
3.l.l.4 GIGARTINA PAPILLATA
( ,
Gigartino papillato, like Iridaea flaccida, is one of the most common red algol species on the Pacific Coast (Abbott and Hollenberg 1976) and has been shown to be one of the more abundant upper intertidal algoe in Diablo Cove and surrounding areas (Burge and Schultz 1973, LCMR 1978). Having a low shrubby form, the gametophytic plants consist of irregularly shaped blades less than 15 cm tall crising from o crustose base. The other generation of this species, the sporophyte plant, hos been shown to be o crustose plant former,1y placed in the genus Petrocelis. Because these crustose plants are not readily separable in the field from those of other crustose genero and species, only the erect gameto-phytic plants are included in G. papillato as used in this report.
Mean percentage cover values for the TEMP +l.0 and +3.0 f t transects are plotted in FIGURES 3-7 and 3-8, respectively. This species was generally more abundant in the +3.0 than the +l.0 ft transects. Excluding stations 14+3 and 8+1, annual cycles are evident in all transects where generally peak cover values B-82-408 3-16
d g . . i i i . . . . i i i i . i i i i i i S - -
R R- -t go i ~
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i
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-R R -
-o o 6 . M ._ o . . i.
JAN JAN JAN JAN JAN JAtJ JAN 1976 l 1977 1 1978 l 1979 l 1980 I 1981 1 1982 I 1983 h)i FIGURE 3-7 B-82-408 ABUNDANCE VERSUS TIME FOR GIGARTINA PAPILLATA AT +1 FT MLLW 3-17
' ' ' ' ' ' ' ' ' 8 I I I 8 i 8 i l STATION 14 ' !
S - -
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, STATION 12 B - -
R n
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$ ,-N s! f s
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o
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39 R $
Z z w m
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- o. / I I s , r , _ ' ' s ii _ , _ - 1_ > s , 'I s,/ o STATION 8 n s -
-2 52.6 g .o I e e
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STATION 11 z.
O s -
R 3 J O O w
$ I v>
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e
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l ,e i i e i i i I i i i iiiiI i i i l i i i l i i i i i, JAN JAN JAN JAN JAN JAN JAN 1976 1 1977 1 1978 1 1979 1 1980 1 1981 1 1982 1 1983 l
FIGURE 3-9
\~)
B-82-408 ABUNDANCE VERSUS TIME FOR l 1RIDAEA FLACCIDA AT +1 FT MLLW l
3-20
o __
S -
3'TATI'ON id ' '
'n' ' ' ' '
in h
hh
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u STATION 11 $
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_a R - _ e o t' i i o
JAN JAN JAN JAN JAN JAN JAN 1976 l 1977 1 1978 1 1979 1 1980 1 1981 1 1982 1 1983 l N_ -
) FIGURE 3-10 B-82-408 ABUNDANCE VERSUS TIME FOR 1RIDAEA FLACCIDA AT +3 FT MLLW 3-21
4 O
Based on field observations, winter reductions in 1. flaccido cover result from blade senescence and " dieback." Most of the spring-summer regrowth each year ;
results from new blade production from overwintering holdfasts. Colonization -l and development of new individuals may also contribute to seasonal increases in percentage cover. Northeraft (1948) observed that 1. flaccido in Monterey Bay, l California recruits year-round. Similar opportunistic recruitment has been observed in Diablo Cove (TEMP, unpublished data). l North (1966) conducted the first ecological investigations at Diablo Canyon in 1966 and provided an intertidal algal species list for Diable Cove. Included in this report were 1. floccida (then known as Iridophycus flaccidum), G. papillata, G. canaliculata, G. coulteri, E. muricota, and others. Although specific obun-dances for individual species were not described, he stated that the intertidal region was nearly completely covered with vegetation. Later studies by the California Department of Fish and Game (CDFandG) at Diablo Canyon reported relative abundances of species encountered, and documented seasonal changes in both plant cover and biomass for some species. Burge and Schultz (1973)
O g concluded that 1. flaccida, G. canaticulata, and G_. coulteri were three of the enore abundant species inhabiting the lower intertidal zones, whereas higher elevation areas were covered by G. papillato (then also known as G. cristota), E_.
muricato, I. flaccida, and Pelvetic fastigiota. Later studies (Gotshall et al.
1977,1978) in similar areas reported that the dry weight biomass of the "Iridaea complex" (1,. floccido plus 1. cordata), G. canaliculata, G. coulteri, and Prionitis l
lanceolata together comprised 60 to 80 percent of the total non-calcareous algol biomass in most low elevational (0.0 ft MLLW) study zones. LCMR (1978) presented the abundances of all major species encountered in 34 band transects sampled bimonthly from April 1976 to May 1977. Similarly, l. flaccida, G.
! pap _illato, G. canaliculata, G. coulteri, and E. muricato were among the 10 most abundant species at the majority of these study sites. More recent field observations (up to December 1982) indicate these species still rank among all species os the more abundant algal components within the Diablo Canyon intertidal region.
s B-82-408 3-22 1
In this report seasonal percentage cover abundances have been analysed and presented for five species in nine band transects for the period April 1976 to October 1982. Annual cycles of greater coverage during summer periods were observed for 1. flaccida, G. papillato, E_. muricato, and in some cases for G.
canaliculata. G_. coulteri varied more irregularly over the period investigated.
These data verify the persistence of these species since the first ecological investigations in Diablo Cove in 1966 by North (1966), and substantiate their continued numerical importance since 1971 when relative abundances for these species were first reported by Burge and Schultz (1973).
3.1.2 INVERTEBRATES The IBT invertebrate data are of three general types: (1) numerical, (2) percen-tage cover, and (3) presence / absence (P/A). For some taxa on the invertebrate data sheet, these three types of data may be recorded at a given station during an intertidal survey. For each type of data there are certain preferred methods or techniques of analysis, and when two or more types of data are recorded for a given taxon (e.g., P/A and numerical data), the choice of analytical method involves a compromise. For example, numerical dato can be converted to P/A data but the reciprocal cannot be done.
There are several reasons for recording more than one type of dato: (1) the relative importance of the invertebrate taxon which determines whether or not its name is printed on the data sheet; (2) the physical size of the individual animal; (3) the position of the individual within the quadrat; (4) whether the quadrat is a Tegula quadrat or a " regular" quadrat; (5) the physical form or l
l habitat-type of the taxon; and (6) whether the taxon has historically been l considered an important species in the context of this study (e.g., predatory snails, or black abalone). The methods for collecting IBT invertebrate data, into which framework the above conditions fit, have been variously described elsewhere (Mayer et al.1981, PGondE 1977, 1978).
l The type of data collected have remained essentially constant since intertidal Survey 03 (August 1976) for five taxa: the aggregating sea onemone 1 U l B-82-408 3-23 l
l
. 1 O
y (Anthopleuro elegantissimo), the rough limpet (Collisella scabra), the hermit crabs (Pagurus spp.), the black turban snail (Tegula funebralis), and the block abalone (Haliotis cracherodii). All individuals of the first four species, regard-less of size of individuals or their position within the quadrat, are counted in the five Tegulo quadrats at each station level. All block obalone, regardless of size or position within the quadrat, are counted in all IBT quadrats at all station levels.
The dato presented in this section are the mean numerical abundances of the first four taxo from the five Tegula quadrats for the intertidal station levels within Diablo Cove and at Diablo Point for which there are continuous data from Survey 01 to the present. The block obalone dato are presented as the mean abundance based on 10 quadrats at the Diablo Cove and Diablo Point stations.
3.1.2.1 ANTHOPLEURA ELEGANTISSIMA Anthopleuro elegantissim_a, the aggregating sea onemone, is distributed in the middle intertidal zones from Alaska to Baja California, Mexico (Morris, Abbott,
\
and Haderlie 1980). A_. elecantissimo exhibits two distinct forms in the intertidal zone: aggregating and solitary individuals. Aggregating individuals are usually small, occuring in dense groups of more than several hun ked individuals per m2 ,
Aggregations are formrJ by asexual reproduction, producing clones of geneti-colly identical individuals, which con have o maximum width of 8 cm across the tentacular crown. Clones observed over several years showed little change, although some individuals had moved (Morris, Abbott, and Haderlie 1980). The large solitary A. elegantissima con evidently be a product of either sexual or osexual reproduction. Their maximum width across the tentacular crown is 25 cm.
Anthopleura elegantissima feeds on small animals and detritus which come in contact with its tentocles. It is the prey of the nudibranch Aeolidia papillosa and i
the sea stor Dermasterios imbricata. According to Morris, Abbott, and Haderlie (1980), A_. elegantissima survive in the vicinity of coastal power plant discharge l plumes where temperatures may exceed ambient by 10 C, but show somewhat B-82-408 3-24
--r-
_~
O C/ reduced reproductive ability when in this environment. A more extensive review of A. elegantissima con be found in PGondE (1979).
FIGURES 3-1l and 3-12 summarize the mean abundance of A_. elegantissimo in the 5 Tegulo quadrots at the Diablo Cove stations from surveys 3 to 40. There are generally more A. elegantissimo at the +3 ft level than at the +1 ft level for all surveys combined (TABLE 3-4).
Generally, the individuals at stations 8+3, i1+1, Il+3 and 12+3 are of the smaller aggregrating form, while those at stations 8+1, 9+1,12+l and 14+3 are larger, solitary individuals. At stations 8+3, Il+1 and 12+3, there is on annual trend toward fewer individuals during summer. As seen in FIGURE 3.12, generally fewer individuals were present during 1977 and 1978 at Station Il+3 than in the oti er years. This decrease in the number of individuals was not seen at any of the other stations.
The wide differences seen between the number of individuals at the Cove stations is probably due to the station tidal height and exposure. Ricketts, Calvin, and Hedgpeth (1968), and Morris, Abbott, and Haderlie (1980) state that A. elegantissimo is mainly found in semiprotected, rocky, middle intertidal areas. Sebens (1982), working in Washington, found that there were higher densities of A. elegantissimo in the upper intertidal than in the lower zones and that the larger onemones (solitary individuals) were usually found in the lower intertidal. A similar situation is seen at the Diablo Cove stations.
Three of the Cove stations, 8+3, Il+1, and 12+3, had a general decrease in the number of individuals during summer. This is the opposite of Sebens' (1982) findings in a mussel bed on Tatoosh Island, Washington. He found the maximum density of individual A. elegantissimo to be during the summer. Dayton (1971),
otso working in Washington, found tFat A_. elegantissimo tended to retreat into protected areas or were killed by desiccation during summe . Decreases seen at some of the Diablo Cove statims may have been due to movement of individuals out of the sampling arecs.
O O B-82-408 3-25
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ABUNDANCE OF ANTHOPLEURA ELEGANTISSIMA AT TWO LEVELS ON FIVE STATIONS 1
IN SURVEYS 3 TO 40 Mean No. Anthopleura/m2
+1 ft +3 f t t
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Large fluctuations were seen in the number of individuals at Station ll+3. This station is often covered by sand, and it is possible that sorne of the changes observed were due to onemones being totally covered by sand during some sampling periods and uncovered during others.
Some of the variabilty between surveys might also be due to fission (asexual reproduction) of the aggregating individuals. Sebens (1982) observed an almost complete doubling of the number of individuals at one of his stations during only one year of a multiyear study on A. elegantissimo. He attributed the increase to fission of about 70 percent of the individuals. He also found that larval settlement was most dense in the higher intertidal, but the number of successful recruits was highly variable during the years of his study. This may explain some of the yearly variability in the A. elegantissima density at the Diablo Cove stations.
3.1.2.2 HAllOTIS CRACHERODil Black obalene, Haliotis crocherodil, typically inhabit the rocky intertidal and subtidal regions to a depth of 20 ft from Coos Boy, Oregon to Cabo Son Lucas, Bajo California, Mexico (Cox,1962). In the intertidal they are usually found along ledges and in crevices; in favorable habitats they are commonly found clustered together. In and around Diablo Cove, H. cracherodii was observed to be one of the most numurous and conspicuous of the intertidal invertebrates (Burge and Schultz 1973, Gotshall et al.1974, North et al.1975). Burge and Schultz (1973) reported that black abalone are more abunded than red abalone (H. rufescens) in the low intertidal at depths of 0 to -2 ft, MLLW. They recorded a mean block obalone density in north Diablo Cove of 2.7 individuals /m2 based on observations of two intertidal transects.
In H_. cracherodii the sexes are separate. Block abalone seem to follow on annual reproductive cycle with fairly well-defined spawning periods. Boolootion et al.
(1962) observed on annual reproductive cycle for H_. crocnerodii near Pacific Grove, Monterey County, with most members of the population spawning between June and October. Leighton and Boolootion (1963) observed spawning in B-82-408 3-29
Haliotis at Pt. Dume, Los Angeles County, from late spring through summer to early fall. For block abalone in Monterey County, Webber and Giese (1969) speculated that the 5 C annual temperature fluctuation along that portion of the Pacific Coast might not of itself control gametogenesis but that the temperature fluctuation together with photoperiod might exert on effect.
f Leighton and Bcolootion (1963) reported field growth rates of 26-30 mm per year for the first two years of life. The growth rate oppeared to be greatly reduced in subsequent years, although one specimen in the 90-100 mm range grew at a rate of 18 mm per year. Wright (1975) observed that growth rates within a population of abalone were extremely varioble.
Minchin (1975) demonstrated that adult block and red abalone could crawl over coarse sand and suggested that sand substrate may not act as a barrier to migration. Movement in block obalone appears to be size dependent to some extent. Bergen (1971) reported that larger individuals remained in place for long periods of time whereas smaller animals left their scars (depressions in the rock) to graze and then returned to the some spot. He also found that large H. crocherodii remained relatively stationary in the field, while smaller ontmals tended to graze at night. Cox (1960) reported that an adult black abalone was observed to remain in the same spot for two years. -
Block obalone are exclusively herbivorous. Abalone removal experiments had no detectable effect on the attached algal community further suggesting that drift algae are tne primary food source. Gut contents from field collected specimens, Leighton and Boolootion (1963), showed that the most frequently occurring food items, in descending order, were brown algal fragments, Gigartino canaliculato, Pelvetic fastigata, Pterocladia pyramidale, Bossiello spp., Corallino spp., Phyllo-spadix spp., and Gelidium spp. In a subsequent laboratory study, the preferred food items were Egregio laevigato, Gigartino spinoso, Macrocystis pyrifero, Gelidium purporoscens, Pterocladio pyramidale, Phyllospadix scouleri, and coral-line algae. Macrocystis, Pelvetia and Gigartina concliculato induced the fostest growth rates in the laboratory.
a B-82-408 3-30
m Predators of adult H_. crocherodil include the fishes Scorpoenichthys marmoratus (cabezon), and Semicossyphus pulcher (sheepshead); sea otters, Enhydro lutris; rock crabs, Concer antennarius; and the sea stor, Pycnopodia heliantholdes (Cox 1962, Burge and Schultz 1973). Besides the above taxo, predators on juvenile black obalene may include the lined shore crab, Pachygropsus cressipes; sea gulls, Larus spp.; and the sea star, Pisaster ochraceus.
More detailed information on the biology of block obalone in the Diablo Canyon study area is available in PGondE (1979,1980 and 1982).
FIGURES 3-13 and 3-14 summarize the mean abundance of Haliotis at the five Diablo Cove study stations. It should be noted again that abalone were counted in all 10 quadrats of the band transects, not only in the five Tegulo quadrots as were the other four invertebrate species. The total number of abalone present at any station level during any survey con be determined by multiplying the mean abundance by 10.
There is a wide range of mean values between the stations with a minimum of no abalone ever observed at Station i1+3 to a maximum of 5.8 abalone /m2 during Survey 23 of Station 9+3. TABLE 3-5 presents the mean values for all stations and levels from surveys I to 40.
TABLE 3-5 reveois that stations in south Diabl . Cove have very low mean abundances of abalone compared to the station levels in northern Diablo Cove.
Station 14+3 mean values lie between these two extremes.
- Graphs for mean abalone abundances at stations 8+ 1, 9+ 1, 9+3, and to some j extent 12+3, have a common trend of relatively lower mean abundances for the l first several surveys and then a sudden, rather dramatic increase in the mean abundance.
Another interesting feature of these graphs is best seen in FIGURE 3-14 and mesi clearly at Station 14+3. Here there appears to be o regular spacing between the times of maximum and minimum mean abundances. The periods of v
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ABUNDANCE OF HAllOTIS CRACHERODil AT TWO LEVELS ON FIVE STATIONS l IN SURVEYS I TO 40 l
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- B-82-408 3-34
y maximum mean abundances fell during winter (December) to spring (April) surveys and the mininum values generally occurred during summer surveys. This is apparent to some extent at all stations at the +3 f t level, but not of the +1 ft level.
Perhaps the most interesting trend of these graphs is seen at stations 8+1 and 9+1, and to a lesser degree et 9+3. Beginning sometime offer Survey 21, all of those stations show a distinct downward trend in tLe mean number of abolone/m2. This is cnost pronounced at Station 8+1 where mean numbers dropped from high levels of nearly 5.0 abalone /m2 to the current (Survey 40) levels of about I obalone/m2. Stati n 9+3 showed a gradual, steady decline in mean numbers from peak values between surveys 4 and 9 but a sudden sharp drop between surveys 23 and 25 is evident.
Clearly, black abalone are found in greatest numbers in those areas which cre-most suitable to them. Good abalone habitat is exposed to moderate to extreme wave shock, usually has moderate to high substrate relief with many cracks, h crevices or under-boulder areas, and is in on area of adequate food supply (either as attached or drif t algae). However, predation by mon and/or sea otter may reduce the numbers of obalone from areas which otherwise may be suitable abalone habitat. The degree to which the present distribution of block abalone in Diablo Cove reflects predation pressure is at present unknown.
The permanent stations in the northern half of Diablo Cove appear to be situated in the best abalone habitat, the station at Diablo Point the next best abalone area, and the stations in the south Diablo Cove area the least suitable for abalone. Although Diablo Point is on extremely exposed area, the substrate there is a hard bedrock generally locking in surface relief necessary for abolvne.
The high relief and high degree of exposure to waves at the north Diablo Cove stations provides good habitat for abalone. While the stations in south Diablo Cove have o low degree of wave exposure relative to the other two areas, this area is subject to strong surf action from late fall through spring. The substrate in this area is generally bedrock and small boulders with low relief and, due to the low wave activity in summer and fall, has a tendency to accumulate sand and J
B-82-408 3-35
p (v) silt. Station ll+3 is almost entirely free of attached algae and at times is almost completely covered with sond.
The relatively lower mean abundances seen at some stations in the earliest surveys with a characteristic sharp increase a few surveys later is probably associated with the difficulty in locating the more cryptic obalone. The sudden, dramatic increase in abalone mean abundance at Station 8+1 during Survey 9 resulted from clarification of search methods for o specific quadrat (quadrat 25).
To count all abalone in this quadrot, it was necessary to get into o series of owkward positions to peer upward into on area under a large boulder and then count only those abalone directly under the quadrat. The difficulty of doing this is apparent in the fluctuations in mean abundances at this station frem Survey 9 to Survey 26. Of the total 924 abalone counted in the 10 quadrats of this station during all 40 surveys, all but 44 abalone occurred in quadrat 25.
The regular spacing of the times of high and low abundances, noted particularly at Station 14+3, might also result, at least in port, from varying oigal cover. The December to April maximum mean abalone abundances generally coincide with the annual minimal levels of algol cover, especially of Iridaeo flaccido (see SECTION 3.l.l.5.). With a reduction in cigal cover, the more cryptic obalone are easier to locate. Although block obalone are known to move, sometimes by as much as 7 m during a 24-hr period, previous studies on the movements of block obalone in the Diablo Canyon area (PGondE 1980) did not reveal any seasonal component to their movements.
The decrease in mean abundance of the abalone at stations 8+1, 9+1, and 9+3 offer Survey 21 are very likely the result of sea otter predation. The sharp decrease noted at Station 8+1 between surveys 21 and 23 probably resulted from predation on a high density of abalone in a relatively small area (about 2 m2),
, One otter feeding for o few days or weeks in this area could reduce the number of obalone significantly (Benech and Colson 1976). The abalone at stations 9+1 or,d 9+3 ore much more evenly distributed throughout the 10 quadrats. At this station, on otters' foraging activities would presumably be spread out over o i
B-82-408 3-36
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V FIGURE 3-16 B-82-408 ABUNDANCE VERSUS TIME FOR COLLISELLA SCABRA AT +3 FT MLLW 3-38
I
- I greater crea resulting in a less drastic decrease in the mean abundance of obalone at these stations.
I 3.1.2.3 COLLISELLA SCABRA Collisello scabra is commonly coiled the ribbed or rough limpet, and occurs from Cape Arago, Oregon to Cabo Son Lucas, Baja California, Mexico and Islo Socorro, Revillogigedo Islands, Mexico (Lindberg,1981). They are found in the upper rocky intertidal and splash zones, and seem to prefer horizontal surfaces and gentle slopes (Morris, Abbott, and Haderlie 1980). Their maximum length is 33 mm (McLean 1978); the largest individuals at Bodego Head, California, have been estimated to be about iI years old (Morris, Abbott, and Haderlie 1980).
This limpet feeds by grazing on a film of algae and diatoms during high tide, and then returns to a specific "home site" where it remains during low tide (Morris, Abbott, and Haderlie 1980). When contacic! by Pisaster ochraceus, a common sea stor, they do not show the chorocteristic fleeing escope response of other limpets and thus are preyed upon by this sea stor (Ricketts, Calvin, and Hedgpeth 1968).
FIGURES 3-IS and 3-16 summarize the mean abundance of C. scabro in the five Tegulo quadrats at the Diablo Cove stations from surveys 3 to 40. There is a greater density of C. scabra at the +3 tidal level than at +1 level, except at Station 14+3 which had only a few individuals /m2 . TABLE 3-6 presents the mean number of C. scabra per m 2 for all surveys combined.
The differences seen in the density of C_. scabra between the two levels reflects the preference of these limpets for rocks in the upper intertidal zones. All the +1 stations and Station 14+3 are wetter than the other +3 stations, and C. scabra is not adapted to survive os well in these wetter areas.
The data for many of the stations indicate that the maximum number of individuals at these stations is observed duririg the October and December t
surveys. Morris, Abbott, and Haderlie (1980) state that in centrol Californio l 0 3-39 B-82-408 l
l .- - _ _ _ _ _
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TABLE 3-6 ,
ABUNDANCE OF COLLISELLA SCABRA AT TWO LEVELS ON FIVE STATIONS IN SURVEYS 3 TO 40 6
Mean No. Collisella/m2
- Station
+1 ft +3 f t
! 8 6 26 9 0 18 Ii 10 65 12 4 35 14 --
2 l
t B-82-408 3-40
- Q maximum settlement of larval C. scabra tal:es place from July to October. This is one possible explanation for the increases seen at the end of the year at some of the stations. Another possible reason for the variability in density is that a rock or boulder with resident C_. scobra might have rolled into one of the sampled quadrats. If this rock were in the quadrat during a survey, the number of sampled individuals would be greater than if the rock were not there. A third possible
.expimation for some of the increased values is the fact that during fall and w nter the algal cove- decreases making it easier to see the rocky surface where the C_. scabra reside.
3.1.2.4 PAGURUS SPP.
Three species of Pogurus comprise the common intertidal hermit crab popula-tions in the Diablo Cove study areas. Pogurus samvelis is probably the most common and abundant species. Its range extends from Vancouver Island, Conodo to Bajo California, Mexico. Within this range P_. samuelis is usually found in the upper to middle intertidal zones. This species shows a marked preference for n
) Tegula shells in the Monterey area (Morris, Abbott, and Haderlie 1980). Another (O common species is Pogurus hirsutiusculus, with a range which extends from northern Japan through Alaska into southern California. P_. hirsutiusculus generally lives in lower intertidal zones than P. samuelis, but the populations overlap. Tequia shells are occupied by this species but much less frequently than by P_. samuelis. The third common hermit crab species is P_. granosimanus.
These hermit crabs are found in tide pools and the more protected areas of the lower middle to low intertidal and subtidal areas from Alaska to Baja California, Mexico. These large hermit crabs also commonly inhabit Tegula shells, Although the adults of these three species are not too difficult to identify to species in the field, the juveniles are very difficult to separate. Because juvenile hermit crabs are ubiquitous in the intertidal zones, no attempt has been made to separate the species. All three species are considered as Pogurus spp.
l l Pogurus spp. are scavengers on plant and dead animal matter. They have been observed to pick tentacles off tube worms and the tube feet off of sea urchins j
b i
G B-82-408 3-41 i
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o (Ricketts, Calvin, and Hedgpeth 1968). These authors also state that Paqurus spp. may under some circumstances attack and kill a snail for its shell.
Hermit crabs are generally inoctive during the day, becoming more active in the late offernoon and continuing through the night ur"l down (Morris, Abbott, and Haderlie 1980). Their major activity seems to be fc ding and searching for new shells to occupy (Ricketts, Calvin, and Hedgpeth 1968).
FIGURES 3-17 and 3-18 summarize the mean abundance of Pogurus in the five Tegula quadrats at the Diablo Cove stations from surveys 3 to 40. TABLE 3-7 presents the mean number of Pogurus/m2 for all surveys combined.
There are, on overage, a few more Paqurus at the +1 level than at the +3 level, except at Station 12 where the density was slightly greater at the +3 level.
Pogurus are found at all the stations, usually throughout the entire year. No one trend is consistently found at all or the stations. The densities of Pogurus at stations 8+1,9+1 and Il+1 seem to show slight increases during the fall of most years. During 1979,1980, and 1981, on increase was seen in the late summer and fall at Station Il+3, while at Station 12+3 the maximum number of individuals during all the years of study was during the February surveys. There was a peak in abundance at all of the +1 stations during Survey 27 (August 1980) but not at the +3 stations.
3.1.2.5 TEGULA FUNEBRALIS The black turban snail, Tequia funebralis, occurs from Vancouver Island, Canada to centrol Bajo Califon .o, Mexico (Morris, Abbott, and Haderlie 1980). Within this range, T. funebralis occurs in the intertidal zone with its greatest population densities generally between the +1 ft and +S ft MLLW (Hewatt 1934, Woro and Wright 1964, Ricketts, Calvin, and Hedgpeth 1968). Within this intertidal zone certain biological and physical factors operate which offect the distribution of T. funebralis. Waro and Wright (1964) report that among the more significant factors are degree of wave exposure, amount of algal cover (or amount of open rock surface available), and daily and seasonal tidal cycles.
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I O FIGURE 3-17 B-82-408 ABUNDANCE VERSUS TIME FOR PAGURUS SPP. AT +1 FT MLLW l 3-43
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JAN JAN JAN JAN JAN JAN JAN 1976 l 1977 l 1978 1 1979 l 1980 1 1981 1 1982 I 1983 f3 FIGURE 3-18 B-82-408 ABUNDANCE VERSUS TIME FOR PAGURUS SPP. AT +3 FT MLLW 3-44
i t
I T
! TABLE 3-7 .
i 2
ABUNDANCE OF PAGURUS SPP. AT i
TWO LEVELS ON FIVE STATIONS IN SURVEYS 3 TO 40 4
l Mean No. Poqurus/m2 ;
Station
+1 f t +3 ft i
i 8 14 10 9 10 9 l 11 15 13 12 22 30 ;
i 14 4 --
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i 31ock turbon snails are primarily herbivorous and feed on many species of cigoe including microscopic algol films, ottached fleshy algae, and drift algae or wrock. T. funebralis displays a definite food preference among the macroscopic oigoe for Macrocystis integrifolio, Nereocystis luetkeano, Rhodoglossum offine and Gigartino conoliculato, its preferred diet in the Monterey Boy creo (Best i964).
Tegulo funebralis are preyed upon by several organisms including the southern sea otter (Enhydra lutris), the red rock crab (Concer antennarius) (Mor;is, Abbott, and Hoderlie 1980), the starfish (Pisoste ochroceus, Pycnopodio belion-thoides, and, for small Tegulo, Leptosterios spp.), and predatory snolls (Acanth- ,
ino spirato and Nucelh emo ginato) (Yornoll 1964). Predators probably limit the distribution of the ble urban snail to forertidal areas (Morris, Abbott, and Hoderlie 1980). There is on indication that T. funebralis may live to be 20 to 30 years old, among the oldest gastropods known (Dorby 1964).
Within the Diablo Canyon study areas, the block turbon snail is the most ubiquitous and abundant animal encountered in the intertidol. The abundance of T. funebralis os mean number of indiviouais per square meter in the T. funebralis quadrots for the four +1 ft stations and the five +3 ft stations in Diablo Cove and
- . on Diablo Point are shown in FIGURES 3-19 and 3-20, respectively. Two major features of these figures are apparent. First, there are generally more T. funebralis at the +3 ft levels at the Diablo Cove stations than at the +1 ft levels, with the exception of Station 14 +3, at Diablo Point. At this station a total of 15 T. funebralis were counted in the T. funebralis quadrats from Survey 3 (August 1976) to Survey 40 (October 1982). TABLE 3-8 presents the mean number of T. funebralis per m2, One very noticeable feature of FIGURES 3-19 and 3-20 is the distinct " sow-tooth" nature of the graphs indicating large fluctuations in the mean abundances of T. funebralis over the study period. At Station 12+1, for example, the menn abundances of T. funebralis fluctuated from less than 1/m2 in Survey 20 to 289/m2 in Survey 25. Fluctuations at the +3 ft levels, while quite large, are not i
B-82-408 3-46 i
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JAN JAN JAN JAN JAN JAN JAN 1976 l 1977 l 1978 I 1979 8 1980 1 1981 1 1982 4 1983 FIGURE 3-19
's B-82-408 ABUNDANCE VERSUS TIME FOR L
TEGULA FUNEBRALIS AT +1 FT MLLW 3-47 l
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(s) FIGURE 3-20 B-82-408 ABUNDANCE VERSUS TIME FOR TEGULA FUNEBRAllS AT +3 FT MLLW 3-48
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TABLE 3-8 4
i ABUNDANCE OF TEGULA FUNEBRALIS
- AT TWO LEVELS ON FIVE STATIONS IN SURVEYS 3 TO 40
.i i
Mean No. Tequio/m2 4
Station
+1 ft +3 f t l i
8 10 120 9 5 45 11 50 90 12 60 150 i l
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as dramatic: of 12+3 the means ranges from a low of 71 T. funebralis/m2 during Survey 15 to highs of over 300/m2 during several surveys.
The mean abundances of T. funebralis at the +1 f t levels at all Diablo Cove stations show seasonal trends. At these stations the highest abundances generally occur in the winter surveys with the lowest abundances, very nearly zero in most cases, occuring in the summer surveys. The magnitude of these differences in winter-summer abundances is best seen at stations 11 +1 and 12 +1. A11 four graphs show the lack of c winter peak in mean abundance during the 197E-1979 winter, surveys 16 (October),17 (December),18 (February), and 19 (April),
At the +3 ft levels of the Diablo Cove stations, there is no definite seasonal cycle os there is for the +1 ft stations. These stations opppear to undergo large oscillations in the mean abundance of T. funebralis through time. There appears to be a very slight tandency for the peaks in mean abundance at the +3 f t levels to be slightly out of phase with those peaks at the corresponding +1 ft stations.
This is perhaps best seen at Station 12 where the highest mean abundances occurred most often during summer surveys.
The definite decrease in T. funebralis numbers noted at the +1 ft levels during surveys 16-19 does not appear at the +3 ft levels.
At the stations sampled, the +3 ft levels in Diablo Cove provide more favorable habitat for T. funebralis than the +1 ft levels, if the +1 ft levels were even marginally suitable, one would expect to see a year-round " resident" population of T. funebralis rather than the seasonal very high or very low obund'ances. The sharp increases in T. funebralis numbers at the +1 ft levels are probably a result of increased wave action during winter acting to dislodge them to lower levels or stimulate them to move down to escope the turbulence.
The degree of wave exposure is probably a significant factor in explaining the almost complete obsence of T. funebralis at Diablo Point and the relatively B-82-408 3-50
F
lower numbers of T. funebralis at the stations in north Diablo Cove (stations 8 ,
and 9) than those in south Diablo Cove (stations lI and 12).
Microhobitat is probably important in explaining some of the variability in the mean abundance of T. funebralis. Some quadrats may provide better shelter to T. funebralis during low tides than other quadrats. This situation is indicated when the abundance of T. funebralis is examined on a quadrat by quadrat basis:
some quadrots consistently have more _T_. funebralis during any survey than neighboring quadrats.
3.2 INTERTIDAL 0.25 m2 RANDOM POINT CONTACT QUADRAT (RPCO)
Random point contact (RPCO) quadrats were sampled together with the inter-tidal band transects in six surveys conducted in 1982. The sampling occurrences are shown in TABLE 3-9.
p 3.3 INTERTIDAL ALGAL SCRAPINGS U Two intertidal algol scroping surveys were completed in February and June 1982 (see TABLE 3-10). Laboratory analysis of the samples was also completed.
3.4 INTERTIDAL BLACK ABALONE TAGGING Nineteen intertidal block abolone tagging surveys were completed through 1982 (see TABLE 3-1I).
3.S INTERTIDAL BLACK ABALONE SURVEY A single intertidal black obalone survey was conducted in November 1981.
3.6 INTERTIDAL STATION PHOTOGRAPHY Intertidal station photography was completed in the six surveys conducted in O 1982 (see TABLES 3-1 and 3-2).
B-82-408 3-51
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9 TABLE 3-9 p (CONTINUED)
$ MONTHLY SAMPLING OCCURRENCES FOR THE RANDOM POINT CONTACT METHOD i- FOR EACH +l.0 FT MLLW OUADRAT BY STATION 8
1976 1977 1978 1979 1980 1981 1y82 4E 4
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TABLE 3-10 EUMMARY OF COMPLETED INTERTIDAL ALGAL SCRAPlb'G/ BIOMASS PROGRAM
+ 2.0 FOOT (MLLW) 4 Station
- Survey and Date 1 2 3 4-01 August 1979 X X X X 02 November 1979 X -- -- --
02 December 1979 --
X X X 03 January 1980 X -- -- --
03 March X 0 04 May 04 June 1980 1980 1980 X
X X
X X
X 05 August 1980 X X X X 06 January 1981 X X --
X 06 February 1981 -- --
X --
07 June 1981 X X X **
j 08 December 1984 --
X X **
08 February 1982 X -- -- **
09 June 1982 X X X **
- 25 scrapes were taken at each station marked "X".
- Station 4 deleted from program.
l B-82-408 3-54 l
I
O TABLE 3-1 l l
SUMMARY
OF COMPLETED INTERTIDAL BLACK ABALONE TAGGING SURVEYS Number in parentheses ( ) is the number of abolone stations sampled Number Number Date Suney Abolone Abalone Togged Recoptured iI/78 1 442 (4) --
1/79 2 --
140 (4) 4/79 3 --
l15 (4) 5/79 4 142 (4) 62 (1) 6/79 5 209 (4) 170 (4) '
O 7/79 9/79 I/80 5
6 7
14 (1)
II3 (4) 168 (4) 169 (3) 136 (4) 212 (4) 3/80 8 73 (2) 157 (2) 5/80 9 --
276 (4) 7/80 10 134 (4) lI8 (4) !
I1/80 lI 66 (3) -l37 (3) 2/81 12 139 (4) 180 (4) 5/81 13 III (4) 222 (4)-
- 7/81 14 29 (3) 151 (3) 8/81 15 29 (1) 112 (1) i 11/81 16 --
86 (1) l/82 17 --
174 (4) 4/82 18 68 (3). 129 (3) 5/82 19 --
18 (1)
O B-82-408 3-55
2
~
3.7 SUBTIDAL SISTER QUADRANT PROCEDURE: MACROALGA AND MACROINVERTEBRATE COUNTS The subtidal sister quodront macroalga and macroinvertebrate counts were completed as part of the five subtidal surveys completed in 1982 (TABLE 3-12).
3.8 SUBTlDAL FIXED CIRCULAR QUADRAT PROCEDURE:
INVERTEBRATE SAMPLING Subtidal fixed circular quadrat invertebrate sampling has been completed as part of the five subtidal surveys completed in 1982 (TABLE 3-12).
3.9 SUBTIDAL SISTER QUADRANT PROCEDURE:
RANDOM LINE POINT CONTACT (RLPC)
Subtidal random line point contact samples were obtained during the five subtidal surveys completed in 1982 (TABLE 3-12).
3.10 CRAB TRAPPING During 1982,19 subtidal crab trapping stations were sampled during five surveys (TABLE 3-13). A sixth survey, scheduled for December, had to be concelled because stormy sea conditions caused hazardous boat operating conditions in all trapping areas. Total numbers of crabs trapped and catch per unit effort for these surveys are presented in TABLE 3-13. A detailed analysis of the crab trapping data obtained from August 1976 to April 1981 was completed and the results were published in a scientific journal (Corroll 1982).
The objective of this analysis was to document several os ects of the Diablo Canyon adult rock crab opulation including (1) seasonal abundance, (2) sex ratio, (3) size composition, (9.' .notting and spawning periods, (5) individual growth rates, and (6) migrotory behavior.
Total numbers of crabs in each trop were tallied and expressed as catch per unit effort (CPUE), i.e., the number of crabs trapped per 24-br trop set. Functional v
B-82-408 3-56
e C O TABLE 3-12 O
+
9
SUMMARY
OF COMPLETED SUBTIDAL TEMP SAMPLING A
8 2
tb. of No. of tb of No.of No. f No. of RLPC 30 m2 are k m2 Algal km Fish Observations Y '
- y" U
Guadrats Sampled Quadrats Sampled Quodrats Sampled Scrapings Taken Quadrat Photos No. Stations (2 repl.)
93 14 Of May-Aug 1976 32 -- 128 128 --
13, I (I repl.) -(I station w/l replicate) 02 Sept-Dec 1976 28 l12 112 IIS 84 116 03 Jm-April 1977 28 112 l12 IIS 84 12 14 68 69 2 14 s 04 May-Aug 1977 17 68 51 '
05 Sept-Dec 1977 3 12 12 12 9 0 13 20 0 2 06 Feb-Mar 1978 5 20 21 --
6 07 April-May 1978 9 36 36 37 0 0 08 June-July 1978 9 36 36 37 0 0 4 (2 rept.), 2 (I repl.)
36 37 0 0 6 09 Aug-Sept 1978 9 36 6
10 Oct-Nov 1978 6 24 24 25 0 10 0 0 0 11 Dec-Jan 1978-79 4 16 16 17 0 6 0
Y 12 Feb-Mar 1979 8 32 32 32 36 0 0 6
$ 13 April-May 1979 9 36 36 6
14 June-July 1979 5 20 20 20 0 0 36 36 0 0 6 15 Aug-Sept 1979 9 36 36 36 0 0 6 16 Oct-Nov 1979 9 36 0 6 17 Dec-Jan 1979-80 7 28 28 28 0 20 20 0 0 0 18 Feb-Mar 1980 5 20 0 6 19 April-May 1980 9 36 36 36 0 20 June-July 1980 4 16 16 16 0 0 0 21 Aug-Sept 1980 8 32 32 32 0 0 0 20 20 0 0 6 22 Oct-Nov 1980 5 20 0 6 23 Dec-Jan 1980-81 2 8 8 8 0 4 4 0 0 0 24 Feb-Mar 1981 1 4 6
25 April-May 1981 9 36 36 36 0 0 26 June-July 1981 9 36 36 36 0 0 0 27 Aug-Sept 1981 0 0 -0 0 0 0 6 (I rept.)
28 28 0 0 0 28 Oct-Nov 1981 7 28 6
29 Dec-Jan 1981-82 4 16 16 16 0 0 28 0 0 6 30 Feb-Mar 1982 7 28 28 31 April-May 1982 10 40 40 40 0 0 6 32 June-July 1992 10 40 40 40 0 0 0 33 Aug-Sept 1982 7 28 28 28 0 0 0 34 Oct-Nov 1982 2 8 3 8 0 0 2 (2 rept.),4 (I rept.)
35 Dec-Jan 1982-83 Survey currently in progress
m . _
- o TABLE 3-13 TOTAL NUMBER OF CANCER ANTENNARIUS CAPTURED, AND OVERALL CATCH PER UNIT EFFORT (CPUE)
FOR SURVEYS 20 THROUGH 34 -
(AUGUST 1980 - DECEMBER 1982)
CPUE Total Survey Period No.of Upper Lower Crobs Mean :
95% ci 95% ci 20 08-80 125 1.74 2.09 1.39 21 10-80 2ll 2.98 3.74 2.22-22 12-80 148 2.29- 2.92 1.66 23 02-81 242 3.80 4.88 2.87 O 24 25 04-81 06-81 380 376 5.27 5.20 6.07 6.01 4.46 4.39 26 08-81 296 4.39 5.28 3.54 27 10-81 449 6.24 7.32 -5.16 28 12-81 321 4.46 5.21 3.71
- 29 02-82 289 3.65 4.49 2.81 30 04-82 230 3.19- 4.73 1.65 31 06-82 129 1.79 2.22 1.36 32 08-82 165 2.29 2.88 1.70 l 33 10-82 366 5.08 6.21 3.94 34 I2-82 survey concelled due to rough sea conditions l
O B-82-408 3-58 i
I - - _ _ .__ - . _ _ . , _
5-regressions (Ricker 1973) of body weight on carapace width were calculated for 200 males and 200 females ranging in size from 70 mm to 155 mm coropoce width. Poired measurements of cheio height and coropoce width were also obtained on a wide range of size-classes in order to characterize allometric changes in growth between juveniles and adults for estimates of size at sexual maturity. Seber-Jolly population size estimates and survival rates (Seber 1965, Jolly 1965) modified for small numbers of recaptures (Ricker 1975), were derived from tag-recapture data for all areas combined.
3.10.1 CATCH ABUNDANCE AND COMPOSITION A total of 9,190 rock crabs was trapped, tagged and released during the 23 surveys from June 1976 to April 1981. Seasonal CPUE tended to be greatest during autumn surveys and leosi during summer surveys, primarily as a result of increased numbers of females in addition to relatively stable numbers of males.
Males generally outnumbered females, as indicated by on overall sex ratio of I.4:1. Annual peaks in percentages of females corresponded to annual maximum (O
v j water temperatsres recorded in Diablo Cove, and were positively correlated with nearshore water temperatures (r = 0.628). This suggests that warmer water temperatures may stimulate inshore migration of females, however, too few tagged crabs were recaptured from deeper areas to verify any seasonal migra-tory patterns. Selby (1980) attributed on autumnal increase in CPUE for female C_. productus off Oregon to a combination of higher feeding rates offer molting and mating, and increased migratory behavior.
The effectivenc3s of boited traps in successfully attracting and capturing crabs depends upon several factors. Bait quality, trop orientation on the substrate, gear saturation effects and prevailing water currents are all known to offect CPUE values (Miller 1979, 1980). For example, in this study, wave surge and turbulence from winter storms occasionally displaced tr@t ' rom their original shallow set locations and filled them with quantities of shell debris and drift algae. Although such adverse sea conditions certainly decreased trop effective-ness, CPUE was still considered a reliable indicator of adult C_. ontennarius m
B-82-408 3-59
4 population density because dato analyses were based on replicate trop-sets over several days.
Catch per unit effort declined from the productive 1976-1977 surveys, reaching low values in 1979-1980 but increasing slightly in the 1981 surveys (FIGURE 3-21). Mean CPUE from August 1976 to December 1977 was 8.6 crabs / trap as compared to only 4.0 crabs / trap from December 1978 to February 1981. The reasons for this decline are unknown, but Benech (1979) documented on increase in predation on rock crabs by sea otters (Enhydra lutris) as the otters reestab-lished their southern range through the Diablo Cove region in the mid-1970s.
After otters exploited their preferred food items of abalone (Haliotis spp.) and sea urchin (Strongylocentrotus spp.), rock crob was preyed upon more intensively (Benech 1981). Sea otter predation significantly reduced rock crab populctions in Monterey Harbor, 200 km north of Diablo Cove, from 1972 to 1974 (Colifornia Department of Fish and Gcme 1976, Hines and Loughlin 1980). Similar effects evidently occurred in the Diablo Cove vicinity.
, 3.10.2 WIDTH AND WEIGHT COMPOSITION
%./
Regressions of body weight (Y) on carapace width (X) for adult rock crabs yielded the following relationships:
Males: log Y = 3.070 log X - 3.703 r=.946 Females: log Y = 2.532 log X - 2.638 r= .954 Mean body weights of moles and females possessing two normal-sized chelipeds were 497 g and 354 g, respectively. Mean coropace width (cw) was 121.5 mm for 5,021 males and iIl.8 mm for 3,668 females, with both sexes displaying similar patterns in size distribution: unimodal curves skewed toward the larger size-classes (FIGURE 3-22).
The observed size composition resulted from trop selectivity for large crabs and was not representative of the C. ontennarius population in Diablo Cove. Less than 3 percent of tagged individuals in the 95-105 mm cw size-class were m
B-82-408 3-60 l
O O O e
l=-
8 15 H
T O Vertical bars represent 95% confidence intervals about the rneans. Number of LL l' trop sets = 72 for all surveys except August - November 1976 and January 1977 (n=75), February 1980 (n-68) and January 1981 (n=65). Sornple size: n=9190.
E
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r l m
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b4N/IN I Y t t t I g 3 ig ig g 3 g I I I g i a I e t 3 SEP NOV JAN MAR MAY JUL SEP NOV DEC FEB APR JUN AUG OCT DEC FEB APR JUN AUG OCT DEC FEB APR
- 1976 - 1977 1978 - - 1979 1980 - 1981 -
FIGURE 3-21 BIMONTHLY CATCH PER UNIT EFFORT (CPUE) FROM AUGUST 1976 TO APRIL 1981. CPUE WAS DEFINED AS THE MEAN NUMBER OF CANCER ANTENNARIUS TRAPPED PER 24 HR TRAP SET.
l 1
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CARAPACE
"""'~~~ N $~2$$bb 8EiNik!$ssslimkN$ h 70 80 90 100 1 10 120 130 140 150 WIDTH (mm) .. .
U '*',.'*****~'.W**.'~'..*~**~.
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20 - *:':P Moles are plotted above the line, females below. Mean coropoce width for moles was 121.5 mm, females 111.8 mm.
1 t
1 l
1 1
FIGURE 3-22 O SIZE FREQUENCY DISTRIBUTION FOR 5,021 MALE AND 3,668 FEMALE C. ANTENNARIUS CAPTURED, IN 5 MM WIDTH INCREMENTS B-82-408 3-62
~
recoptored as compared to more than 15 percent in the 135-145 mm cw range .
Furthermore, juvenile rock crabs were commonly observed not only in the subtidal os well. tropping areas during SCUBA dives but also in adjacent intertidal a Factors which may have contributed to the paucity oferejuveniles in the tra possible difficulty of entry, noncitractiveness of bait, or presence of larger crab already in the trops.
3.10.3 MOLTING AND GROWTH Greatest percentages of molting males and females (molt stages A to B) generally occurred in cutumn and early winter although recently molted crobs were found throughout the year. Relatively few recent molts were tropped with ,
intermott crabs (stoge C) often comprising over 95 percentTheof the catch .
observed percentages of recently molted individuals were low estimates of th actual proportion in the population because crabs in the soft-shell e condition ar l relatively immobile and seek shelter until the new exoskeleton hardens e support movement. Moreover, soft-shell crabs are incapable of feeding until the main period of cuticle bordening is completed (Knowles and Carlisle 1956) and would almost certainly have a low susceptibility to capture.
Sinole-molt size increases for adult female rock crabs varied o from 13 percen 26 percent in coropoce width and 50 percent to 70 percent in body weight .
Smaller crabs tended to have proportionately greater width and weight increa than larger crobs. Only three males were recaptured after ,
e dato molting but th indicate slightly greater size increases for males than females
, cy which a tenden explains the larger maximum size eventually attained by moles. Comparable growth rates are known to occur in the Atlantic rock crab, Concer irroratus with width increases varying from 19 percent to 27 percent and weight from 52 percent to 82 percent (Haefner and Van Engel 1975).
The majority of growth data were obtained on females smaller than 105 mm cw ,
a size group comprising less tFon 30 percent of the total female catch Very few B-82-408 3-63
n v overage-sized crabs molted at liberty, and none of the recaptures from the largest size-classes exhibited growth. Rock crabs in the 80-105 mm cw range have on intermolt duration of approximately 5-8 months. Large crabs ( >l35 mm i cw) recaptured after 10-14 months at liberty had not molted since the time of tagging, indicating that rock crabs in their near-terminal instars have on extended molt cycle of 16 months or longer.
Lengthening of successive intermoit cycles is a generalized feature of many decopod Crustacea (Passano 1960) and has been documented in other Cancer spp.
(Butler 1961, Hancock ad Edwards 1967, Anderson and Ford 1976).
Biofouling of the carapace was another indicator of intermolt duration. Large barnacles (Bolonus tintinnabulum) growing on the coropoce cf some crabs were estimated to have settled at least 8-10 months earlier, based on unpublished growth studies using subtidal settling plates in Diablo Cove (C. P. Ehrler, TEMP, personal communication). Other epifauna observed on rock crabs included the bornocles B. crenatus, B. aquila, Tetraclito squamosa, and the tubicolous polychaetes Phropmotopoma californico, Spirobranchus spinosus, and several V
species of Serpulidae.
Approximations of growth curves for male and female C. antennarius are based on the observed molt increments of adult crabs end asymptotic maximum carapace widths of moles and females (approximately 160 mm cw and 150 mm cw respectively). If the largest crabs are assumed to be in their sixteenth post-larvol instar (based on C. magister growth studies by Butler (1961)), then moles of approximately 135-140 mm cw and femotes of 125-130 mm cw would be in their fif teenth instar, and males of 120-125 mm cw and females of 110-1l5 mm cw would be in their fourteenth instar.
The maximum age of C. ontennarius is probably no more than 7 years. Butler (1961) estimated the maximum age of C_. magister to be 8 years, and Reilly and Sailo (1978) estimated 7-8 years for the Atlantic rock crab, C. irrorotus.
O 1
B-82-408 3-64
d 3.10.4 MATURITY AND REPRODUCTION ,
The approximated growth curves for male and female rock crabs diverge between 60 mm cw and 80 mm cw, suggesting that the onset of sexual maturity occurs within this range. The smallest ovigerous female octually observed was 73 mm cw. The minimum size at maturity for C. irrorotus is opproximately 60 mm cw for females and 69 mm cw for males (Scorrott and Lowe 1972).
- Adult male C. ontennarius possess larger, more robust chelipeds than females, o secondary sexual chorocteristic which appears during the pubertal molt.
Unsexed juveniles have a constant ratio between chela height and coropoce width up to approximately 65 mm cw. Beyond this size, discontinuities in relative growth occur os chela height to carapace width ratios of sexually motore males and females diverge from the juvenile proportions.
As in other Brachyuro, discontinuities in growth rate of appendages are more distinct in the male than the femote (Teissier 1960). Associated regressions of
/
\ chela height (Y) on coropoce width (X) yielded the following relationships:
s Adult moles: log Y = 1.217 log X .891 r=.966 Adult females: log Y = 1.175 log X ~ .897 r=.970 Juveniles: log Y = .991 log X .602 r=.983 G
The relative growth curve and opproximated general growth curve both. indicate o pubertal molt in the 60-80 mm cw size range, but too few individuals in this range were obtained to occurately define the 50 percent maturity value of the
, population by using the method of Somerton (1980). At this size, crabs would be within their tenth to twelfth instar and opproximately 2 years of age. Laboro-tory reared C onthonyi ottoin sexual maturity of the thirteenth instar (Anderson and Ford 1976), and C. magister matures at the eleventh or twelfth instar under natural conditions (Butler 1961).
s B-82-408 3-65
O V Ovigerous females were present during all months of the year but were most abundant in winter. Ovigerous rock crabs in the Point Conception coastal area, 150 km south of Diablo Cove, were also relatively abundant during winter 1980- <
1981 (P. N. Reilly, Colifornia Department of Fish and Game, personal communi-cation).
' Observations on a female rock crab which molted and moted in captivity (copulation con only occur immediately offer female ecdysis) indicate that approximately ll weeks elapse between insemination and appearance of the egg mass. Recently extruded eggs are bright orange, but become dark brown as the embryos develop. Seven to eight weeks are required for development and hatching of eggs at ambient temperature (12 2 2 C).
Larval crab obundance was not assessed during the trapping program but earlier zooplankton studies in the Diablo Cove vicinity revealed that greatest concen-trations of Cancer spp. larvae occur during spring and early summer (lconberry and Warrick 1977).
r%
- 1 3.10.5 MARK AND RECAPTURE STUDIES From 7,879 crabs tagged with sequentially numbered suture tags, 494 (6.3 percent) were recaptured within 2-18 months of release. Recopture rate declined logarithmically as the time interval between release and recapture increased. An overage of 3.5 percent of the releases were recaptured offer 2 months, l.5 percent offer 4 months, and less than 0.1 percent offer 10 months.
Factors offecting recapture rate over time include natural mortality and emigration, which reduce the obsolute number of tagged crabs in the creo of release, and the processes of recruitment and immigration, which reduce the proportion of tagged to untagged crabs.
Average annual tag-loss rate was estimated to be 14.0 percent per year by comparing the number of tog losses to the number of tog retentions in the sample of recaptured crabs. Tag-loss is known to bias Seber-Jolly estimates of population size and survival rate, as well as cousing loss of precision in the i
L B-82-408 3-66
estimates (Arnoson and Mills 1981). Population size estimates (N;*) for the ~
Diablo Cove area (opproximately 20 hectores), ranged from o maximum of 10,590 crabs in November 1976 to a minimum of 1,060 crobs in August 1979 (0.05 ~
to 0.005/m2). In a similar mark-recapture study on C_. irrorotus, Drummond-Davis et al. (1982) calculated population densities of about 0.5/m2 in a small kelp bed off Nova Scotia.
Directionality of rock crab movements, inferred from tog returns, occurred predominantly along a deep channel leading into Diablo Cove. No seasonal trends were apparent to indicate on annual migratory pattern of _o substantial segment of the ' population. Crobs at liberty from 1-5 days tended to remain in the immediate vicinity of release, with only 3.8 percent recaptured in adjacent tropping areas (o distance of up to 2 km). In contrast, 21 percent of crabs at liberty from 2-18 months were recaptured in adjacent tropping areas, but the majority were recaptured close to their original release site. . In on analysis of Dungeness crab migration off northern California, Gotshall (1978) found that most tagged crabs remained near their release sites for several months.
Because fishing effort in the present study was concentrated along a narrow -
reach of coastline, long-distance movements away from the area of release were incompletely monitored. However, migratory distances of up to 5 km were recorded for several individuals which were recaptured in commercial trops set .
outside of the study creo. Rock crabs are therefore capable of long-distance movements but often remain in the some area for several months, perhaps moving only short distances while foraging.
3.11 SUBTIDAL FISH OBSERVATIONS l
l Underwater fish observation surveys have been conducted since August 1976.
During 1982, surveys 29 through 34 were comp'eted (no stations were sampled in surveys 32 and 33 because of poor underwater visibility) (see TABLE 3-12).
Fixed sampling sites were selected in areas likely to experience increases in
- water temperature from the thermal discharge of the power plant and in areas t
with no predicted increase (see FIGURE 2-5).
I l B-82-408 3-67
3 Nine species of fish were selected for detailed summaries on the basis of their overall abundance or representativeness of a particular Diablo Cove guild of fish.
A brief summary of the composition, total abundance, and overall rank of each species is included for all surveys. These selected species' obundance potterns are summarized on on annual basis.
This underwater fish observation task is one of several ongoing efforts which has contributed to the fish biology dato base. The Department of Engineering Research (PGandE) monitors the party boot Catch per Unit Effort, and conducts intertidal fish studies. The California Department of Fish and Game conducted fish abundance studies at rondom stations. Dr. Wheeler J. North of California Institute of Technology has been regularly recording fish presence and obsence data since 1966.
The underwater vertical transect stations are positioned between the fixed
-10 ft and -15 ft (MLLW) TEMP subtidal sampling station monuments which are centrally located within each study area. These transects provide documentation of the composition and abundance of species at different depths within on area.
The horizental transects extend along the -10 ft and -15 ft isoboths within each study area to document composition and abundance of the species at selected depths. The transect lines extend along established compass headings. All transects have o fixed length (50 m) and a fixed width (2 m) on either side of the transect center line. A 2 m distance was determined to be the minimum required for adequate fish identification. Transects were therefore sampled only under conditions of of least 2 m latero! visibility.
A dive team, consisting of two divers, does the recordings and observations for the underwater stations. One " benthic" diver records all benthic fish and measures bottom water temperature at each end of the benthic transect.
Simultaneously a "midwater" diver makes all midwater fish observations. The benthic diver notes all fishes seen within 2 m of either side of the transect line and within I m of the substrate while looking forward. The midwater diver records all fishes seen in a cylinder of approximately 4 m diameter centered about 3 m above and slightly forward of the benthic diver.,
f
%)
B-82-408 3-68
)
v The six fish observation stations are all located within 50 m of shore. All stations are subjected to breaking waves or large swells during much of the year.
The bottom relief of the stations is generally rocky with large boulders, ledges, and pinnocles interspersed with sand or cobble-filled channels. During summer, on algal surface conopy of Cystoseiro reproductive fronds or Nereocystis forms over much of these areas. The permanent stations are grouped in three pairs of 50 m long transects with the paired transects oriented approximately perpen-dicular to each other.
4 in north Diablo Cove, Station 6 is at a depth of approximately 12 ft and runs parallel to the northwest arm of Diablo Cove. A large pinnacle is present at one end of the transect, and large boulders and rock outcroppings covered with Botryoglossum are abundant along the transect. Station 7 originates from the west end of Station 6 and descends rapidly across small ledges and outcroppings to o depth of 22 ft.
The fish observation stations in south Diablo Cove (stations 8 and 10) are located 7
in a shallower, more protected area with less water circulation
- hon the stations
(
in north Diablo Cove. Station 8 runs along the 10 ft isobath, crossing low outcroppings, ledges, and channels. Station- 10 is similar to Station 8 in most respects; however, o few large rock outcrops are present at the deeper end of the transect. Pterygophorc and Laminario produce a dense understory canopy during the summer at both of these stations. The South Diablo Cove stations are
(. in on oreo likely to be in contact with the power plant's cooling water discharge; the north Diablo Cove stations are not expected to be affected.
Fish observation stations 13 and 14 ore located outside " South Cove," approxi-motely 0.6 kin south of Diablo Cove. The bottom relief at these stations is much greater than that of the stations in Diablo Cove. These South Cove transects cross toll pinnacles rising to depths as shallow as 10 ft and descending to depths of 30 ft. Station 13 has patches of cobble and Station 14 has sand channels and cobble near the seaward ends of the transects.
O B-82-408 3-69
\
j During the 34 surveys from August 1976 through November 1982, more than 56,063 fish of 56 species were recorded in Diablo Cove and South Cove. Nine species made up 93 percent of the total young and adult fish observed in the 250 transect samples: senorita (28.8 percent), olive rockfish (18.6 percent), blue rockfish (1:. 8 percent), black and yellou rockfish (10.4 percent), becaccio (7.4 percent), tubesnout (6.8 percent), striped surfperch (3.4 percent), pointed greenling (1.9 percent) and block surfperch (0.9 percent).
Overall, the juvenile life stages of the area's fish species accounted for 60 percent of the total fish observed. The juvenile senorito and . ,ckfish accounted for 60 percent of the juvenile fish observed.
There were 22,357 oduit fish observed, which were composed of 53 recorded species. The five most obundant adult species were: senorito (40.1 percent),
tubesnout (17.0 percent), blue rockfish (8.3 percent), striped surfperch (7.2 percent), and pointed greenling (4.9 percent). The juvenile rockfish were the most abundant of the juvenile fish with olive rockfish comprising 29.4 percent of
\ the young; blue rockfish,19.1 percent; black and yellow rockfish,14.5 percent; and bocaccio,12.4 percent. In addition, senoritos made up 21.2 percent of the juveniles.
Approximately 60 percent of the total fish counted were observed within I m of the bottom. Each station had similar overall midwater and benthic fish distribution. The most numerous fish seen on the benthic portion of the transects were juvenile rockfish. Seasonally, more than 50 percent of the total fish observed were seen during the summer. The fall and spring each accounted for a total proportion of about 18 percent and approximately one percent in the winter.
The following species were selected for detailed abundance summaries and analyses:
o Sebastes serranoides (olive rockfish) o Sebastes mystinus (blue rockfish) v B-82-408 3-70
C
( o Sebastes chrysomelos (black and yellow rockfish)
- o. Sebastes paucispinnis (bocaccio) o Sebastes rostrelliger (gross rockfish) o Embiotoca lateralis (striped surfperch) o Embiotoca jacksoni (black surfperch) o Oxylebius pictus (painted greenling) o Scorpaenichthys mormoratus (cabezon)
These nine species represent a cross-section of five rockfish that share the water column during their early life history and separate into their own particular habitat as adults. The blue rockfish and olive rockfish remain in the water column, the bococcio moves offshore, and the black and yellow rock fish and the grass rockfish become bottom dwelling.
The striped surfperch and black surfperch both utilize a water column habitat within several meters of the sea bottom. The striped surfperch feeds upon invertebrates living on the shallow olgal covered rocks, and the block surfperch feeds upon prey found on the deeper and algol turf covered substrates.
Two fish species representative of benthic habitat that are both obundant and share the some habitat are the small painted greenling, which feeds upon small crustaceans and fish eggs, and the cabezon, which feeds on large invertebrates and small fish.
l The relative abundance of these selected species are summarized by year and for each station.
I 3.11.1 BLUE ROCKFISH Blue rockfish, Sebastes mystinus, are nonmigratory and concentrate in dense l
schools in or near rocky pinnacles and high relief areas from the surface to
, depths of 90 m.
O B-82-408 3-71
O I
Spawning probably takes place once a year. The eggs of blue rockfish are fertilized internally. Larvol incubation is estimated to take 30 days. Some males and females reach maturity at age three (190-200 mm). However, males and females may not spawn until reaching 290-300 mm, respectively, and not all females are mature until age ten; but 80 percent have spawned at age six.
Researchers have estimated that from 50,000 to 300,000 eggs per year were spawned, depending on the size of the individual and assuming one spawning period a year. The larvo are reported to occupy the epipelagic zone for several months. In the late spring juveniles are found in near-shore kelp canopy.
Blue rockfish are probably the only species of rockfish that feeds heavily on algae. Our studies have found Nereocystis sporphytes are a major food item in the Diablo Cove vicinity. Additional life history information is presented in PGondE (1979).
Blue rockfish ranked third in abundance for all years and accounted for 14.8 percent of all the fish encountered in the underwater fish survey. From 1976 through 1982, there were 7 oduit blue rockfish and 24 juveniles per transect. A total of 8,289 blue rockfish were observed in the 24 subtidal surveys from 1976 through 1982; 6,433 of the totai fish were classified as juveniles. The peak obundances of both adult and juvenile blue rockfish were observed in 1979 (FIGURE 3-23).
Juvenile numbers decreased from o maximum of 49 in 1979 to i per transect in 1982.
Blue rockfish were not numerous in the summer (FIGURE 3-23). During the spring, which is the season for peak ' larval abundance offshore, the juvenile numbers were lowest. Larval blue rockfish are reported to occupy the epipelagic zone for several months. During the late spring, juveniles (45-50 MgTL) move into near-shore algol canopies. By fall, juveniles reach a size of 65-95 MMTL (Miller and Geibiel 1973).
(v3 B-82-408 3-72
' ' ' ' ' ' ' ' ' ' ' ' ' i ' I I i STATION l'0 '
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1 ! Al na n i k, , r i WXI - nu M 3iv Iv !! D las I54 91 l
! JAN JAf4 JAN JAN JAN JArd ' JAN 1976 1 1977 1 1978 8 1979 1 1980 I 1981 1 1982 1 1983 x = benthic transect dato o a midwater ironsect dato 1
FIGURE 3-23 SEBASTES MYSTINUS BLUE ROCKFISH B-82-408 3-73
I I i l 1 8 i i i I 3 1 8 I I I I I i 4 .I gs . .
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g . O xX -
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JAN JAtJ JAN JAN JAN JAN JAN 1976 1 1977 1 1978 8 197? I -1980 1 1981 1 1982 I 1983 x benthic transect dato o s midwater transect dato i
r FIGURE 3-23 SEBASTES MYSTINUS BLUE ROCKFISH (CONTINUED)
C
( B 82-408 3-74 I
h
Blue rockfish are often associated with rocky reefs or pinnacles, as well as open deep water. Our study areas cross a variety of habitats. In south Diablo Cove the substrate is low in relief, north Diablo Cove has moderate relief, and South Cove has high relief.
The numbers of adult and juvenile blue rockfish in south Diablo Cove have been consistently low throughout all the surveys. Corresponding with the low numbers is the low relief on both stations 8 and 10. Next greatest abundances of blue rockfish were seen at north Dioblo Cove stations 6 and 7, corresponding to the increase in bottom relief at these stations. These stations in North Diablo Cove are also closer to the open ocean and receive greater mixing than the other cove stations. The highest abundances of blue rockfish were observed at stations 13 and 14 which are located near South Cove.
3.11.2 OLIVE ROCKFISH The olive rockfish, Sebastes serranoides, is an important sport fish throughout central California.
Because of the similarity between juveniles of olive and yellowtoil rockfish, the divers combine the two species. Adult olive and yellowtail rockfish are common in the near-shore sport fisheries; however, no adult yellowtail rockfish have been observed by divers. Little is know of their specific life history.
Olive rockfish represented 18.6 percent of all the fish observed. Out of a total of 10,404 olive rockfish, 4.6 percent were adults (482) and 95.4 percent (9,922) were juveniles. Olive rockfish ranked second in total abundance behind senori-tas, which represented 28.8 percent (16,123) of the total composition. From 1976 through 1982 on overage of 38 olive rockfish per transect was recorded.
The years of peak obundance for both adult and juvenile olive rockfish were 1977 and 1979. Adults and juveniles were most obundant during the summer months U B-82-408 3-75
Q ond were observed in the lowest densities during the spring months (FIGURE 3-24).
Adult olive rockfish veere typically found mixed with b!ue rockfish near high reef substrate in oper. water or in the vicinity c.f kelp. Juveniles were often seen congregating within the protective stipes of Cystoseiro osmundacea in our study.
area.
More juvenile olive rockfish were seen in the low bottom relief areas. Cysto-seiro density was higher at stations a and 10 in south Diablo Cove than at stations in north Diablo Cove or South Cove. The greatest obundance of adults were found in the deeper water above the high relief of stations 7 and 13.
Two peaks in abundance for juveniles were seen at all stations during 1977 and -
I979.
3.11.3 BLACK AND YELLOW ROCKFISH
)
J Black and yellow rockfish, Sebastes chrysomelas, were usually found near shore in shallow water. Most research has demonstrated little or no movement between home ranges. The black and yellow rockfish are taken only occasionally '
by the sport fishing boats. However, the skiff fisherman do catch black and yellow rockfish from Port San Luis in the Diablo vicinity. Other than movement and territorial behavior, little is known of their life history.
1 Because of the difficulty in differentiating between juvenile black and yellow rockfish and gopher rockfish, the two are combined by the divers. !
Black and yellow rockfish comprised 10.4 percent of the total fish observed. A '
total of 5,834 were recorded with 933 adults and 4,901 juveniles. Black and yellow rockfish ranked fourth in abundance for all years. An average of 3 oduits and 18 juveniles per transect was observed between 1976 to 1982.
L.
B-82-408 3-76 l
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JAN JArJ JAN JAN JAN JAN JAN 1976 1 1977 1 1978 1 ?97* 1 1980 1 1981 1 1982 I 1983 x = benthic transect data o a midwater transect dato FIGURE 3-24 SEBASTES SERRANOIDES/FLAVIDUS OLIVE ROCKFISH 3-77 i
l L ,
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JAN JAf4 JAN JAN JAN JAN JAN g 1976 1977 1978 1979 1 1980 1 1981 1 1982 1 1983 g 1 1 9 x a benthic transect data o a midwater fronsect dato FIGURE 3-24 SEBASTES SERRANO! DES /FLAVIDUS OLIVE ROCKFISH (CONTINUED)
B-82-408 3-78
Q The oduit and juvenile densities reached maximum abundance in different years; 4 per transect fe: oduits in 1979 and 80 juveniles per transect in 1981. Of all the rockfish, the adult block and yellow rockfish is the most sedentary. Adults live l m the bottom occupying a home range for most of their life. The same tagged l
oddt fish have been seen repeatedly at the some location over o period of two years. The numbers of cdult black and yellow rockfish have ranged from less than I to 4 per transect from 1976-1982 (FIGURE 3-25).
There is little seasonot fluctuation in the number of adults. Juveniles, however, are notably more abundant in the spring and summer. Juvenile block and yellow rockfish were the only rockfish that were present in large numbers during the spring.
Block and yellow rockfish are commonly found on shallow high relief stations I with boulders and ledges. Stations 6 and 7 in north Diablo Cove provide ideal l
l habitat as evidenced by overage densities of 5 and 7 block and yellow rockfish per transect. The low relief of south Diablo Cove supported lower densities of fish than any of the other areas. Juvenile block and yellow / gopher rockfish were, however, most abundant in south Diablo Cove than in the other areas. The high density of Cystoseiro and shallow water depth probably accounts for the species' preference for this oreo.
I l
3.11.4 BOCACCIO Juvenile bocaccio, Sebastes poucispinis, appear infrequently in the study area.
However their high abundance during their brief presence ranks this species fifth in overall abundance. The bococcio comprise 7.4 percent (4,165) of the total fish observed. No adults have been observed at the sompling stations. Bococcio are commonly caught offshore by both sport and commercial fisherman.
The peak obundance of bocaccio was observed during 1979 (51 bococcio per transect). A second peak of 32 individuals per transect occurred in 1981 (FIGURE 3-26). Bococcio only occurred during the spring and in peak obundance in the summer.
J B-82-408 3-79
1 I
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JAfJ JAfJ JAfJ JAN JAN JAN JAN 1976 1 1977 I 1978 9 197? I 1980 1 1981 1 1982 I 1983 x = benthic transect dato o a midwater transect dato FIGURE 3-25 SEBASTES CHRYSOMELAS BLACK AND YELLOW ROCKFISH B-82-408 i
3-80
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. n
, _ STATION 14 ,
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1976 1977 1978 1979 ! 1980 1 1991 1962 1983 g 8 1 1 1 1 x = benthic tronsect data o e midwoter transect dato FIGURE 3-25
, SEBASTES CHRYSOMELAS -
! BLACK AND YELLOW ROCKt ISH I (CONTINUED)
B-82-408 3-81
i e i i i i i i i i i i i i i i i i e i e i i j , , STATION 10 ,
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i o e e i e i Et i n e i T e e s e e i o e a e e a JAN JAtJ JAN JAN JAN JAt4 JAN 1976 1 1977 1 1978 1 1979 8 1980 I 1981 1 1987 8 1983 i
x = bentbic transect dato
- o s midwater transect dato FIGURE 3-26
.i SEBASTES PAUCISPINUS
] B-82-408 BOCACCIO 3-82
- . - --. .. ~. .. ._. = . - _ . . . . -
t N
__ i . . i i i i . . i i i i e i i i i i i i i . .
i ' STATION 14 QS - -
d e
t o R - -
B 8 O
) U
. XX h
g 2 m ! XO E,
ak g . STATION 13 -
W O 4 X mR -
O -
5 m x i
x
< 0 X
2 1 t t i i Qt i ive r X9 i e t i w I i a e i 4 JAN JAN JAN JAN JAN JAN JAN 1976 1 1977 l 1978 I 1979 8 1980 1 1981 1 1982 e 1983 x = benthic transect dato o a midwater transect dato l
l t
l i
FIGURE 3-26
.1 SEBASTES PAUCISPINUS BOCACCIO (CONTINUED)
B-82-408 3-83 l
.- .. - . - _ . , , _ . _ . _ . _ . ~ - , - - _ _ . . . _ - . . . . . _ _ _ . - - _ _ . . _ _ . _ _ . . . . _ . . _ _ _
1 5
O Juveniles of bocaccio are aggressive predators attacking other juvenile rockfish of equal or larger size. They were found in abundance in .the sampled areas associated with large numbers of other juvenile rockfish. In 1979 and 1981, juvenile blue and olive rockfish were present in relatively high numbers.
Bocaccio abundance was highest on Motion 13 in 1979 south Diablo Cove and lowest on Station 7 in north Diablo Cove (FIGURE 3-26). In 1981 bococcio were only found in high numbers on Station 13 and present in D:ablo Cove.
i 3.11.5 PAINTED GREENLINGS Painted greenlings, Oxylebius pictus, are residents of rocky reef habitats.
Individuals are extremely territorial and remain at a selected site for long periods of time. 3 Reproduction is seasonal and egg masses are laid on rock surfaces. Indications -
are that pointed greenlings have a long spawning season from July to April in centrol California. Eggs require about 16 days at 13 C before hatching.
8 The species' major food items are pondoliol and spirontocarid shrimp, other small crustaceans, and demersal fish eggs.
i Detailed studies by DeMartini (1976) provide information on the pointed green-lings' life history.
Since 1976,1,089 pointed greenlings have been seen on the six stations. All of l
L the individuals reported were adults. Painted greenlings represented opproxi-i motely 1.9 percent of the total fish observed and 4.9 percent of all oduit fish.
They rank eighth in total abundance. On the overage, there have been l
opproximately 4 individuals per transect observed since 1976.
! The abundance of pointed greenlings increased from o previous low of 2 per transect to 16 in 1980 and then leveled off at 5 per transect during 1981 and 1982, respectively (FIGURE 3-27).
l i
- B-82-408 3-84 l
l l
STITI ld ' '
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( X X, x -c f X X N X, o
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1976 1977 f t978 1979 f 1980 f 1981 f" 39g2 f" g983 x = benthic transect data o a midwoter transect dato FIGURE 3-27 OXYLEBlUS PICTUS PAINTED GREENLING
}
s/ B-82-408 3-85
\ ,
i i a l l l 1 i i a i i i i i i i i i 1 i i J
STATION 14 Q9 O
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< x -
8 O kX X lC X X[X >f X
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X X X X X
- = 0 g ) y h
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6 I i X
w &g . STATION 13 -
X X
( X i :< 3C O
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g .
x :c j x *<
x f.
- x
- (
C x x * -
4 xx y X <
X X
2 f I l l I l l l XXI l l 1 1X l i1l l l l i 1 4 JAN JAN JAN JAN JAN JAN JAN 1976 1 1977 1 1978 8 19?? I 1980 1 1981 1 -1982 I 1983 x = benthic transect dato o = midwater transect data FIGURE 3-27 OXYLEBlUS PICTUS PAINTED GREENLING (CONTINUED)
B-82-408 l
l 3-86 l
- t. ., , , , , - . _ - - . . , - - . - , , - - , - - - - - - - ~ - - - - ~ ~ - ~ ~= - - ' ' ~ " ' * " ~ ~ ~ ' " ~ ^ - ' - ' ' ' ' " ' " " ~ ~ ' ' " ' * ' ' ' ' ~ ' ' * ^
-. - _ - - . . . .. - =-
A marked increase in the abundance of pointed greenlings occurs in'the fall and
- winter. Approximately 2 fish per transect were recorded in the spring and-summer months and 6 fish per transect in the fall and winter months (FIGURE 3- t 27).
Pointed greenlings were least abundant at stations 8 and 10 in south Diablo Cove and were most abundant at Station 13 (6 per transect).
2
! 3.11.6 GRASS ROCKFISH The gross rockfish, Sebostes rostrelliger, ranked seventeenth in abundance, but is i notable because of its gradual increase in abundance over the survey years.
S;nce 1972 more than 170 oduit grass rockfish have been observed among the six j sampling stations. Virtually all of the individuals observed have been adults.
The brown / green juveniles are grouped with Sebastes spp. -juveniles. The majority of gross rockfish were seen during the fall and winter months (FIGURE l-j 3-28).
I Gross rockfish are commonly found nearshore (-5.0 ft MLLW to 20 ft) hiding in the surfgross, Phyllospadix, or shallow-water algae. They were found most abundantly in south Diablo Cove (stations-6 and 7). However, they are rather evenly distributed at all stations through time (FIGURE 3-28).
3.11.7 STRIPED SURFPERCH Striped surfperch, Embiotoca lateralis, are reported to live in cold water near
! the bottom of rocky substrate. They are reportedly found at deeper depths in southern California than in northern California. The reported depths 'of preferred distribution averaged 40 ft in LaJolla,17 ft in Santa Barbara and 12 ft in northern California.
Striped surfperch are normally'demersal in an epibenthic habitat along the open coast. This species is reported to be more specialized in its feeding behavior and B-82-408 3-87
' ' 8 i e i i i ' ' ' ' ' ' ' ' 8 i iii ii V , _
STATION 10 -
R - .
- ( g x x '<
m x x < X > < 0 x N** (
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, t I t f I xi :( I -tXt t t I > ki I ff B t IX l I t JAN JAri JAN JAN JAN JAN JAN 1976 1 1977 1 1978 1 1979 1 1980 t 1981 1 1982 8 1983 x = benthic transect dato o a midwoter transect dato FRAME 3-28 SEBASTES RASTREL_LIGEB _
GRASS ROCKFISH s
B-82-408 3-88
k w
-- ii i i i i i i i i i i i i i i i i i i i i i 2
STATION 14 O s -
- d e
2 -
B U
x 1, x x x. - -
x x , x
- e e i i w&g STATION 13 .
W O ~
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, 1 1 1 1 I X f i 1 1 [l > 1 I Ix l 1 IX bx ! ! I W 1976 1977 1978 1979 1980 1981 1982 1983
- s x benthic transect dato o a midwater transect dato FRAME 3-28 SEBASTES RASTRELLIGER GRASS ROCKFISH (CONTINUED) l B-82-408 i 3-89
V food preference than the block surfperch. Feeding areas of the striped surfperch are usually shallow reefs covered by algae in which it finds its prey.
The striped surfperch is the most numerous surfperch observed thus for.
Approximately 7 individuals per transect have been recorded. Overall, they account for 3.4 percent of the total fish observed (7.2 percent of the adult fish, and about one percent of the juveniles).
During 1979, 8 oduit striped surfperch per transect and- I juvenile striped surfperch per transect were observed. From 1980 through 1982 approximately 4 individuals per transect have been at the sampling stations (FIGURE 3-29).
The adults are distributed evenly through the seasons os evidenced by observa-tions of 4 individuals per transect in the spring to 6 individuals per transect in the winter. The juveniles are most abundant in the summer (FIGURE 3-29).
Striped surfperch in the Diablo Canyon area are observed above the tops of reefs and in shallow turbulent habitat. They feed on crustaceans or other inverte-brotes suspended above the substrate. At the more protected south Diablo Cove which stations are calmer than the exposed stations at north Diablo Cove and south Diablo Cove, the relative abundance of striped surfperch is lower.
r 3.11.8 BLACK SURFPERCH Black surfperch, Embiotoco jacksoni, live both in boys and along the open coast.
Their young are born olive. The young of nearly all of the Embiotoco perch are born in the spring or early summer with the exception of the black surfperch, which appear throughout the year.
Mating usually occurs in the spring. Both sexes mature in the first year. Black
! surfperch occupy a broad range of habitat, and their feeding is generalized and not specific in preference. However, some preference is indicated for algol turf covered substrates.
\
m B-82-408 3-90
-..+,-..m- , . - , . - - . - - . , . , - - - - - - - . - . , .,..,,,.-,--,m, ,.... .- ..... . - - , . - . , --, - .- .w-..-,.,--..,#,--- ,,
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' I I i i i STITIOt410 .
R -
X O O
NX <
X s
N < x x XNh o
STATION 8 .
S -
O S X
- R -
8 e .
ba vhX L M i O w v M II X
yo - v s == v 0 '
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STATION 7 .
N O x Q Z R - x .
- x x 3 x 0 .
X :k .X
< X XN <
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X X K
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7 ) 0000 C X e,
( o 0, Lu i
STATION 6
- x. ,!
x x l
R -
X <
- X X 1 < X $X X X X M X
X g X N x l
x @ 3 o l I l ! I l I I i l D 1 CO IO I I I l 1 *t di oi t JAN JAfJ JAN JAN JAN JAN JAf4 1977 1978 1 1979 I 1980 I 1981 1 1982 1 1983 1976 1 1 x a benthic transect dato o = midwater transect dato FIGURE 3-29 EMB10TOCA LATERALIS STRIPED SURFPERCH B-82-408 3-91
l l
l l
- I i l l l l l l l l I I I I l l l 1 I il t i I J
STATION 14 QS a
O
$2 -
B
- ( X < X Xg
, n n M n k OXM D3 M X D NMU Y E
O l w
E g . STATION 13 .
O Z 2 D X
- :( X X
, I I IN O I I n i I k i El I NI N II N IX f3 m at I i JAN JAN JAN JAN JAN JAN JAN 1976 1 1977 1 1978 1 1979 8 1980 I 1981 1 1992 I 1983 x = benthic transect dato o a midwater transect dato FIGURE 3-29 EMBIOTOCA LATERALIS STRIPED SURFPERCH (CONTINUED)
(
B-82-408 3-92
C\
C The block surfperch coexists with the striped surfperch and often competes for territory. In our study area, striped surfperch, block surfperch, and pile surfperch are common and rank in abundance in that order. . Black surfperch comprised 0.9 percent of the total fish obseried, 2.2 percent of the total number of adult fish (448) and 0.2 percent of all the juvenile fish.
From the survey onset through 1982, black surfperch abundance has ranged from I to 2 individuals per transect. The maximum abundance occurred in 1979 (FIGURE 3-30).
Seasonally, more adults were recorded in the fall and winter months (2.0 individ-uals per transect) than in ibe spring and summer months (I per transect (FIGURE 3-30).
No notable abundance differences were seen between stations. Fewer adults were found in south Diablo Cove Station 8 than in the other stations.
3.11.9 CABEZON N. s Cabezon, Scorpoenichthys mormoratus, are found in most rocky arcos. The specific habitat occupied depends on the stage of development. Eggs are laid in large masses, usually on clean flat sloping rocks. Cobezon eggs are fertilized internally. Spawning commences in late fall and probably ends in early spring.
Peak spawning occurs in January. Female cabezon con spawn more than once a year. Nests are estimated to contain from 40,000 to 100,000 eggs. The eggs hatch offer on incubation period of several weeks.
Cabezon prey on egg masses of other fish, molluscs, and fish. A majority of the cabezon's prey in the Diablo vicinity is comprised of juvenile rockfish. Abalone are also common prey items of the cabezon in this area. See Anonymous 1981 for a detailed description of the cabezon's life history.
Though cozebon accounted for less than one percent (0.6) of the total fish observed, it is on active predator and plays on important role on the trophic
\O B-82-408 3-93
b s -
STATIOA 10 '
I R -
X M < bg x k <
- x < x x M J STATION 8 i
.g s -
..J O
3g _ x ,
8
. u
@ X g x x, x :c o
x < xx < x x X e x xxM E
E
& STATIOA 7 S . . .
w
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Z x xx * *
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STATION 6 i
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I i
j 2 - -
x <
x x
- a l i I I I I :( I Mxt xE I i1l < 1 x ! txd i 1 JAti JAt4 JAN JAN JAN JAt4 JAN 1976 1 1977 8 1978 l 1979 I I?80 1 1981 1 1982 I 1983 x = benthic transect dato l o a rnidwater transect dato i
l l FIGURE 3-30 l
I C EMBIOTOCA JACKSONI
(' BLACK SURFPERCH i B-82-408 3-94
m _ ,
i J
O 9 I i l i I I I I I i 1 I i i i i i 1
-- l I 0 S -
O 2 - X x
8 >
o x x x < .<
X g x x x o *l N if xx , x x s
O I w
& STATION 13 .
S .
W
< x O x -
hg x
- c e X i I tx x
1 I I x
I Nxl f XX x* ft I I Ix II I I I I t t t o JAN JAN JAN JAN JAN JAN JAN I 1983 g 1976 l 1977 l 1978 l 1979 9 1980 I 1981 1 1982 g
x = benthic transect dofo o a midwater transect dato l
l FIGURE 3-30 EMBIOTOCA JACKSON!
BLACK SURFPERCH (CONTINUED)
B-82-408 3-95
i i
i levels of the Cove's fish communities. From I?76 through - 1982, 326 oduit cozebon were seen at the six sampling ' stations.~ Cobezon rank thirteenth in-obundance among the other species of oduit fish.
A peak obundance of 2 cabezon per transect was recorded in 1979 and was repeated in 1980. Cabezon abundance was low in the summer only (less than one individual per transect)(FIGURE 3-31).
Cabezon were found commonly in shallow water often on high relief pinnacles or - '
! on egg masses. Males defending their nests were observed on Station 6, in north Diablo Cove (a high surge area on flat sloping rocks). The high relief stations 3
yielded more observations of cabezon than the lower substrate areas of south Diablo Cove stations 8 and 10 (0.8 and 0.7 individuals per transect, respectively). - <
3.'l2 SUBTIDAL SETTLING PLATES Collection and re-emplacement of settling plates continued on a bimonthly schedule on six stations (6-10, 8-10, 9-10,10-10,12-10 and 19-10). Surveys 34 i .through 39 were completed during the year (see TABLE 3-14). Collected plates l
have been frozen prior to laboratory data collection.
l 3.13 IN SITU TEMPERATURE MONITORING Subtidal and intertidal temperature data have been recorded from July 1976 to the present. The purpose of these measurements is twofold: to develop a boseline assessment of temperature regimes in the vicinity of Diablo Cove prior to power plant operation, and to provide on interpretive data base to supplement marine biological investigations at subtidal and intertidal sampling locations.
The existing temperature data base spans over a six-year period at six subtidal and four intertidal locations in Diablo Cove. ' Temperature measurements were ,
also recorded at eight additional subtidal and 10 intertidal stations during the first year of the study.
i B-82-408 3-96 ;
- - . - . - - - - - . . - . __L______.
O V
i i i i i i i STATION 10 i ii i i i i i i -
i i i i i i r s -
R -
, x x e Xi X XX < X N M E,
U STATION 8 b3 J
O t
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8 U
+-
a b X k X X X X I
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$s m
STATION 7 i
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< X X X l k, x x if x I *x x ><
- x x f td I
, _ STATION 6 ,
t R -
X y X g< l N M
o ! ! I x. I l !kI t x1 l X< X 1 I* <l < l l* lN ] l l JAf4 JAfJ JAN JAN JAN JAN JAN 1976 1 1977 1 1978 1 1979 9 1980 1 1981 1 8982 i 1983 x a benthic transect data o a midwater transect dato FIGURE 3-31 i
SCORPAENICHTHYS MARMORATUS
' CABEZON B-82-408 3-97
s A
-- i i : i i i i i i i i i i i i i - i i i i i i i :
J STATION 14 -
9s -
d e
t -
e 2 -
B X U x W X
+ o X n N :(
- X N X ):
h O I i
w&g . STATION 13 .
, W t -
l' OR D
- I
! to X 4
, I t t t t i II t X XX l X e tX kI I IX XI e X t i JAt4 JAN JAN JAN JAN JAN JAN 1982 I 1983 1978 1979 1 1980 1 1981 1 1976 1 1977 1 1 x : benthic transect dato o = midwater tronsect dato FIGURE 3-31 SCORPAENICHTHYS MARMORATUS '
CABEZON (CONTINUED)
B-82-408 3-98
O O k.
s
$ TABLE 3-14 i
SUMMARY
OF COMPLETED TEMP SUBTIDAL SETTLING PLATE SURVEYS Plates Plates i
Survey Study Retrieved / Survey Study Retrieved /
Date Date
, Number Year Installed Number Year Installed 4
Per Station Per Station i
July 1976 01 01 6* November 1979 21 04 2 September 1976 02 01 1 January 1980 22 04 2
, November 1976 03 01 2 March 1980 23 04 2 i
January 1977 04 01 2 Mcy 1980 24 04 2 March 1977 05 01 2 July 1980 25 04/05 6 Y' May 1977 06 01 2 September 1980 26 05 l l 3 July 1977 07 01/02 6 November 1980 27 05 2 i September 1977 08 02 1 January 1981 28 05 2
! November 1977 09 02 2 March 1981 29 05 2 January 1978 10 02 2 May 1981 30 05 2
! March 1978 II 02 2 July 1981 31 05/06 6 l May 1978 12 02 2 September 1981 32 06 I July 1978 13 02/03 6 November 1981 33 06 2 September 1978 14 03 l January 1982 34 06 2 i
November 1978 15 03 2 March 1982 35 06 2 January 1979 16 03 2 May 1982 36 06 2 i
Marco 1979 17 03 2 July 1982 37 06/07 6 i May 1979 18 03 2 September 1982 38 07 l l July 1979 19 03/04 6 November 1982 39 07 2 j Scstember 1979 20 04 1 l
- Installed only.
l B-82-408 I
1 4
, b This report presents a summary of subtidal water temperature dato collected at
- subtidal Station 8-10 in north Diablo Cove (see location map, FIGURE 2-1) and subtidal Station 12-10 in south Diablo Cove, and intertidal air / water tempera- l ture data from intertidal Station 12+2 in south Diablo Cove, from January 1981 to November 1982. ' Eorlier temperature data from subtidol~ locations in north Diablo Cove are also presented in order to illustrate long-term seasonal trends in water teraperature.
3.13.1 SUBTIDAL TEMPERATURES I
Water temperatures within Diablo Cove are influenced by both large-scale coastal oceanographic phenomeno and local coastal topography. As a generaliza-i tion, three current " seasons" occur during the year: upwelling, oceanic, and i Davidson (FIGURE 3-32). During the spring and early summer, upwelling results -
- from the combined e.fects of prevailing north-northwesterly winds and Coriolis
! forces. Nearshore surface waters are moved offshore and replaced by colder, i i
l nutrient laden bottom waters. However, localized upwelling may occur at any
! time of the year in the lee of headlands such as Point Buchon, north of Diablo Cove. When prevailing winds subside during summer months, upwelling ceases and the oceanic season ensues. During this period water temperatures are j influenced by the cool southerly flow of the California current. In. late summer or early fall, the northward flowing Davidson current develops inshore of the j California current creating a warming trend a;ong the coast. ;
Subtidal temperatures recorded in both north und south Diablo Cove generally reflected these seasonal changes. Weekly mean temperatures and associated maximo and minima for each station are presented in FIGURE 3-33. South Diablo Cove was consistently warmer than north Diablo Cove. The protected :'
l
- nature of this site location apparently causes a greater residence time of circulating water, thus allowing increased solar warming. Coldest annual
!- temperatures in both areas occurred during the period March through June with
! minimo os low as 9.5 C. Warming trends during fall months produced water I
temperatures which occasionally exceeded 17.0 C. Although a generni seasonal 4 -
pottern exists, there are many departures from seasonal trends os evidenced by i
l B-82-408 l
i 3-100 l
I
, , ~ c__._. . . . , _ _ . - - _ - _ , _ . . . . _ _ _ _ _ . _ . , . _ _ . - _ _ _ - - ~ - - - - _ , _ _ _ _ _
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8
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'J STATION 8-10
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l \ 1%
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STATION l2-10 -
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. i
- VALUES INCLUDE s,/ STATION 12+2 i n
AIR TEMPERATURES 1
1 DURING TIDAL l l\ EXPOSURE I L 22 -
,3 . g ,
I g ti / -
I ,L in 11 gg 11I g Il lI I II i I gi l lI II I *
( /l yg i ii I \ g g a g /g g
~\p I i h, I I \1 ,1 t l gy Ii yll II ll 11 \ i g! i'
'l / v ng i fg s; ' 1f q
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- , ,/ i, ,; 'i
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i JAN 81 APR 81 JUL 81 OCT 81 JAN 82 APR 82 JUL 82 OCT 82 JAN 83 FIGURE 3-33 WEEKLY AVERAGE WATER TEMPERATURES FOR T STATIONS 8-10,12-10,12+2 (SUBTIDAL j AND INTERTIDAL, 1980-1982)
B-82-408 3-102 TERACORPORATION
h[\ rapid temperature changes which could occur at any time of the year. For example, temperatures os high as 14 C were occasionally recorded during the upwelling season. Conversely, localized upwelling during the fall warming season sometimes dropped temperatures several degrees below the expected norm.
An example of diurnal fluctuations in subtidal temperatures is illustrated in FIGURE 3-34. During a 72-hour period in early May a gradual warming trend occurred from dawn to dusk, followed by cooling during nighttime hours.
Minimum temperatures occurred about one hour offer da%reak. This pattern suggests that incident solar radiation is the primary factor controlling these fluctuations. To determine whether these changes may have been influenced by warmer receding intertidal water, the predicted tide curve for that period was superimposed over the temperature record. No apparent tidal effect was observed.
3.13.2 INTERTIDAL TEMPERATURES Weekly mean air / water temperatures and corresponding maximo and minimo from January 1981 through November 1982 of Station 12+2, south Diablo Cove, are presented in FIGURE 3-33. The same general pattern in annual temperature fluctuations described for subtidal stations occurred at the intertidal locality.
However, due to periodic exposure to air, intertidal areas are subject to wider variations in temperature. FIGURE 3-35 illustrates on example of intertidal temperature changes in Diablo Cove resulting from the mixed semidiurnal tides which occur along the California coast. As the +2 ft elevation became exposed I to air during late morning and early afternoon hours, temperatures rose above ambient water temperature to a maximum of 23.5 C. Immersion subsequently returned temperatures to ambient (10.5 C). When exposure occurred during nighttime hours temperatures fell below ambient, in this case to o minimum of 4.0 C.
l l
Intertidal and subtidal temperatures continue to be monitored et permanent l
l locations in the Diablo Cove vicinity with additional microloggers to be deployed in early 1983 at intertidal Station 23+2,100 m north of the Diablo Cove B-82-408 3-103
O O O l
L i 8 FREDICTED TOAL HEK:HT TEMPERATURE 12-
, o n .l.,
d lE
,U l.0 s
i
- d 11- .
3 1
la \ Q
'"*5 g
1 r
o w e 10- <
0.0 N O
h % %' -0.,
i 9 . . A\%%\\V DAY A\NNIGHT.N4' x%%%\%V .
j 2400 2400 2400 t
TIME (HOURS PST)
FIGURE 3-34 DIURNAL TEMPERATURE RECORD DIABLO COVE - STATION l2-10 (-3.05 m)
MAY 6-9,1978
- b O N
O O 8
30 -
PREDICTED TIDAL HEIGHT TEMFERATURE
THERMISTOR El.EVATION
< THERMISTOR EXPOSED TO AIR
~
1.5 20 -
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FIGURE 3-35 TEMPERATURE RECORD FOR INTERTIDAL STATION 12+2 SOUTH DIABLO COVE l DECEMBER 8-9,1978
discharge structure, and Station 13-32, opproximately 200 m directly offshore from the discharge structure.
3.14 IN SITU SOLAR 1RRADIANCE MONITORING Radiant solar energy in the visible light spectrum (400-700 nm) is necessary for algol photosynthesis and primary production. Photosynthetically active radiation-(PAR) impinging on Diablo Cove was measured continuously from 1981 to 1982 at two permanent subtidal locations (-10 ft. MLLW north Diablo Cove and -10 ft.
south Diablo Cove) and one permanent terrestrial-location (approximately +88 ft.
MLLW) (see FIGURE 2-1). in addition solar energy was measured at the -
terrestrial station. The purpose of these measurements was to develop a baseline assessment of PAR within Diablo Cove and to provide on interpretive data base to supplement both laboratory algol growth experiments and field biological investigations.
Quantum sensors (Ll-COR Model LI-192S (underwater) and Model LI-1905 (air))
measured PAR in units of microeinsteins/m2/ sec, I microeinstein being equiva-lent to 6.02 x 1017 photons. At the subtidal stations measurements integrated over a 2-minute period between the 400-700 nm wavelengths were stored on magnetic tape at 20-minute intervals using Sea Data Model TLR-l microloggers.
At the terrestrial station, both integrated and instantaneous measurements were taken at 5-minute intervals. Integrated values reduce errors in measurement that con occur in rapidly changing light conditions.
A pyranometer sensor (LI-COR Model LI200SB) measured solar energy (Watts /m2 ) of the terrestrial location. The sensor's spectral response does not cover the full range of the solar spectrum (280-2400 nm) but the induced error is generally less than 5 percent under most conditions (LiCor Inc. 1981). Both integrated and instantaneous readings of solar energy were recorded using the some interval used in PAR measurement. Microloggers were exchanged at the i
subtidal locations at opproximately 45 day intervals with serviced and calibrated f units containing unused tapes. The permanent terrestrial location had a service interval of opproximately one week. Recorded topes were then decoded and the B-82-408 3-106
data transferred into computer memory storage for future use. Magnetic tapes containing original data were permanently stored.
3.14.1 SURFACE IRRADIANCE Measurements of PAR of the terrestrial monitoring site were used to opproxi-mate solar irradiance values at the surface of Diablo Cove. Mean daily .
I irradiance curves for each month in 1981 and 1982 are presented in FIGURES -
3-36 to 3-39. Maximum values of full sun plus sky PAR occurred in June of both 1981 and 1982 reaching nearly 2000 microeinsteins/m2 /see with an opproximate daylength of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. The month with least PAR was December with maximum values below 1000 microeinsteins/m 2 /sec and on approximate daylength of i
10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />.
3.14.2 SUBTIDAL IRRADIANCE Several factors influence the degree of submarine illumination at depth including
-(1) light attenuation due to surface reflection, (2) transient illumination peaks i due to surface refraction, (3) light extinction resulting from dissolved and suspended particulates and the seawater medium itself, and (4) shading from algal canopy cover.
Underwater PAR values at -10 ft MLLW in south Diablo Cove are presented as mean hourly irradiance curves for each month of 1981 and 1982 (FIGURES 3-36
< to 3-39). Highest daily PAR values always occur between i100 and 1300, when the angle of solar incidence on surface waters is greatest, thus minimizing reflection. These hours of maximum illumination had . greatest PAR values during spring months for the following reasons: (l) increasing day length and angle of solar incidence, (2) subsidence of nearshore turbulence from winter storms resulting in less light attenuation by suspended particulates, (3) reduced algol canopy cover.
Greatest' mean underwater PAR values exceeded 400 microeinsteins/m2 /sec in spring months of 1981 and 1982, with high values otso occurring in July 1982.
B-82-408 3-107
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B-82-408 3-108
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l SEPTEMBER,1981 AND 1982 B-82-408 3-110
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FIGURE 3-39 DIABLO COVE INCIDENT (SOLID LINE) AND UNDERWATER (DASHED LINE - 10 FT MLLW) MONTHLY MEAN LIGHT VALUES BY HOUR, OCTOBER, NOVEMBER AND DECEMBER,1981 AND 1982 B-82-408 3-ill
J With decreasing daylength in fcil and cigal canopy cover reaching maximum densities, submarine illumination in south Diablo Cove fell to its lowest monthly mean volves in October 1981 and September 1982. However, water clarity in areas offshore from Diablo Cove usually improves during fall months when calm sea conditions prevail. Although fewer suspended particulates are present in fall, algal canopy cover apparently results in a significant reduction in submarine illumination.
Mean daily irradiance curves were compared between the south Diablo Cove monitoring site and the north Diablo Cove site (both at -10 ft MLLW), and no significant hourly differences were found in long-term mean irradiance levels (FIGURE 3-40). However, short-term differences between areas may occur os a result of differences in tidal dispersion of suspended shoreline particulates.
When transported into subtidal areas on falling tides these drift algal fragments and fine grained sediments can cause noticable reduction in nearshore water l clarity.
3.15 IN SITU WAVE Ocean surface wave data were collected beginning in July 1981 to the present, at a permanently moored wave and current recording station located approximately 2200 feet due west of the west intake cove breakwater. The purpose of the wave recording subtask is to gather information on the occurrence of major storm episodes which could have significant impact on the populations of marine species being monitored for thermal effects in Diablo Cove.
The wave recorder is a self-contained pressure sensing device which automati-colly measures and records on magnetic tape the pressure (psig) of the overlying water column. The instrument is located on the mooring cable at a depth of 30 ft l
(MLLW). As this depth of water changes with the height of the passing wavc 'he j instrument senses and records the pressure changes. The significant characteris-i tics of waves include the height and period of waves. Since these characterishes l
vary widely among waves arriving within a brief period of time, the resulting b
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NORTH AND SOUTH DIABLO COVE MAY 1982
N changes in water pressure must be frequently sampled within a correspondingly short period of time to match the wave events.
The wave recorder is programmed to collect a burst sample of waves (water pressures) every six hours. The burst sample is composed of 128 pressure measurements taken 2.5 seconds apart. The information recorded on the instrument's magnetic tape is then read into a computer which calculates the peak wave, mean wave, and significant wave for each 5.33 minute sompte period taken every six hours. Given the fixed length of the sampling interval and calculating the number of zero height crossings above 30 ft (seo surface datum),
it is possible to estimate the average frequency or period of the waves during the sampling interval.
The results of the wave recording subtask for the period of July 1981 to November 1982 are presented graphically in FIGURES 3-41 and 3-42. These figures illustrate the calculated significant wave height, mean wave height and maximum wave height for each six-hour sample point during the periods the i instrument was deployed. On several occasions, weather conditions and instru-
] ment servicing prevented a continuous deployment of the recorder. The calculated overage wave periods are also included in FIGURES 3-41 and 3-42.
These values were employed in the calculation of the wave ottenuation factor used to calculate the wave heights illustrated in FIGURES 3-41 and 3-42, according to the pressure response function Pr(T) defined by the formula:
i l
A H = pr(T) A h l
where AH = actual wave height
! Ah = wave height calculated from pressure measurements l
T = period of the wave train O
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3-116
The pressure response function is given by:
pr(T) = ccos hk) h where k = k(T) where k = wave number corresponding to period T D= water depth Z = height of the transducer above the bottom The wave number function is given implicitly by the equations:
kg - for deep water gT and 2x for shallow water k* = F and was taken for k = ks + kd/2 Since the formula only approximates a theoretical wave attenuation factor, the wave heights reported at this time are intended for use in identifying the occurrence of significant wave events by relative comparisons. Though the calculated wave heights appear to be in reasonably good agreement with the field observations of waves in the creo, the heights should not be interpreted as records of true wave heights until the instrument's wave ottenuation factor con be evoluoted specifically for the instrument's sensor and the hydrodynamics of the sampling location. ,
O B-82-408 3-il7
4.0 ANCILLARY STUDIES in addition to the field sampling tasks described in the previous sections, on additional study was conducted to determine the effects of the discharge during
" heat treatment" of the power plant cooling water intake conduits. This study is described ir: the following section.
4.1 LABORATORY HEAT TREATMENT THERMAL EFFECTS STUDY Based on operating experience at other West Coast power plants, it is antici-pated that the Diablo Canyon power plant cooling water intake conduits will become fouled with marine organisms which will settle and grow on the conduit walls. Eventually, this biofouling will interfere with water movement through the conduits and will have to be removed. A stonderd procedure for controlling the biofouling involves recirculating the water moving through the cooling system, increasing the temperature in the conduits to a level that is lethal to the fouling organisms (usually barnacles and mussels). When this procedure is carried out, the volume of the cooling water discharge into Diablo Cove is diminished and the temperature of the water is increased over o short (1-5 hours) period.
Prior to 1982, o large number of experiments was conducted to determine the thermal effects of the power plant cooling water discharge during normal operation. During 1982, a second series of experiments was conducted to determine the thermal effects of heat treatment because the discharge tempera-tures during heat treatment are predicted to be above those of the discharge during normal operation. The earlier studies included thermal gradient experi-l ments that showed that most fish avoid water above lethal temperatures. In
! oddition, short-term, high temperature critical thermal maximum experiments conducted only on fishes provided insights as to their tolerance of temperatures of the discharge during heat treament. No comparable experiments were i conducted on algal and invertebrate species. The species of cigoe and inverte-brotes experimented upon in the 1982 studies were chosen to represent those l occurring in the immediate vicinity of the discharge structure which is where the o
)
v B-82-408 4-1 t
t i t greatest influence of the higher discharge temperatures is predicted to occur .
during heat treatment.
k k
A.brief description of the purpose, objectives, methods and species studied in these experiments is included in this chapter. Complete descriptions of the methods and results will be included in on addendum to the " Compendium of Therrnal Effects Laboratory Studies," o document which will be submitted to the Board in January 1983. This addendum will be sent to recipients of the
, compendium later in 1983.
The purpose of these experiments was to determine the effects of anticipated discharge temperatures during heat treatment for short durations on the marine organisms of Diablo Cove. The objective was to be able to assess the potential 4
effects of these temperature exposures on the shallow water species occurring in close proximity to the discharge structure.
4.1.1 METHODS in each experiment run, a control treatment with a temperature equal to the laboratory holding temperature, and four test temperature treatments were
, used. The test temperatures ranged up to 35 C, but species known to be l relatively less heat tolerant were not exposed to temperatures beyond those at which 100 percent mortality was estimated. In all experiments, the organisms
[ were placed into the test tanks at the laboratory holding temperature and (in all but the control tank) the temperature of the water in the tank was increased so that the test temperature was reached one hour later. The tank was held at the test temperature for one hour. Subsequently, the temperature was decreased to the holding temperature by the end of the third hour.
Following the experiment run, the organisms were held in the laborotory at the holding temperature for 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> to determine if any subsequent effects appeared. For the oigoe, observations were mode of discoloration, blecching, and disintegration of the thalli. For the animals, observations were made of movement responses to prodding and death. These observations were made prior B-82-408 4-2
O C to the experiment, at the end of the three-hour experimental period, and at the end of the 96-hour postexperimental period. Based on model studies, it was determined that the heat treciment temperatures are likely to contact only those organisms that reside in close proximity to the discharge structure. For this reason, the animals were acclimated to 24 C to simulate the theoretical normal discharge temperature in this localized area.
In most cases, the organisms were temperature adjusted from the ambient collecting temperature up to 24 C in the laboratory,' of a rate not exceeding I C per day. The organisms were then held at that temperature for a minimum of two weeks, at the end of which time they were considered to be acclimated to the holding temperature. Some animals with higher thermal sensitivity, which would have experienced mortality in the laboratory at 24 C, were acclimated to lower temperatures. Most of the algae were temperature adjusted but not acclimated because during the laboratory holding time required for this process, diatom fooling and deterioration of the plants because of low light conditions, s made it difficult or impossible to assess any temperature effects.
4.1.2 RESULTS A total of 27 species was studied in the 15 experimental runs completed (TABLE 4-1). These included one fish,13 invertebrates and 13 olgae. Additional species included in this study (indicated by "*" next to the name) listed in TABLE 4-1 were included because space was available in tanks during tests of other more important species.
Detailed presentation of the results of these experiments will be included in the forthcoming addendum to the " Compendium of Thermal Effects Laboratory Studies."
U B-82-408 4-3
i TABLE 4-1 SPECIES INCLUDED IN 1982 HEAT TREATMENT THERMAL EFFECTS EXPERIMENTS Fish Rock prickleback (Xiphister mucosus)
Invertebrates Acanthina punctulata Concer antennarius Haliotis cracherodii
- Holiotis rufescens
- Hemigrapsus nudus
- Ocenebra circumtexto
- Pachygrapsus crassipes Paqorus spp.
Patiria miniata
- Pisoster ochraceus
- Strongylocentrotus purpuratus
- Tequia brunnea Tequio funebralis b Alace Botryoglossum farlowianum Cystoseira osmundacea
- Egregio menziesii Endocladio muricata Gastroclonium coulteri
- Gelidium coulteri Giqartina canaliculata Giqartino papillata Iridaea flaccida Laminario dentigero Nereocystis luetkeano
- Pelvetic fastigiato Pterygophora californico l
l
- Species studied only because of space available in the test tanks.
B-82-408 4-4
5.0 LITERATURE CITED Abbott, I. A. and G. Hollenberg.1976. Marine algae of California. Stanford University Press. xii + 827 pp.
Anderson, W. R., and R. F. Ford.1976. Early development, growth and survival of the yellow crab Concer anthonyi Rathbun (Decapoda, Brachyuro) in the laboratory. Aquaculture 7: 267-279.
Arnoson, A. N., and K. H. Mills.1981. Bias and loss of precision due to tog loss in Jolly-Seber estimates for mark-recapture experiment. Conodion Journal of Fisheries and Aquatic Sciences 38: 1077-1095.
Benech, S. V.1979. Sea otter population expansion dynamics at the southern front. American Zoologist 20: 880. (abstract).
.1981. Observations of the sea otter, Enhydra lutris, population between Coon and Rattlesnake Creeks, January - December 1978. Ecomar, Inc.,
Technical Report No. Vil-3-78, Santo Barbara, California,39 pp.
Benech, S. V., and E. W. Colson. 1976. Size and distribution of the California sea otter population in the vicinity of Diablo Canyon Nuclear Power Plant, October 1973 - December 1975. PGondE, Dept. Engng. Res. Rpt. No.
7846.1 l-76.
Bergen, M.1971. Growth, feeding and movement in the black obalone, Haliotis
' crocherodii, Leach,1871. M.S. Thesis. Univ. Calif., Santa Barbara. 59 pp.
Best, B. A.1964. Feeding activities of Tegula funebralis (Mollusca, Gastropodo).
Veliger 6 (Suppl.): 42-45.
Boolootion, R. A., A. Formonformaion, and H. C. Giese. 1962. On the reproduc-tive cycle and breeding habits of two western species of Haliotis. Biol.
Bull.122: 183-193.
Burge, R. T., and S. A. Schultz,1973. The marine environment in the vicinity of Diablo Cove with special reference to abalones and bony fishes. Calif.
Dept. Fish and Game, Mar. Res. Tech. Rpt.19. 433 pp.
Butler, T. H.1961. Growth and age determination of the Pacific edible crab, Concer magister, Dano. Joumal of the Fisheries Research Board of Canada 18: 873-889.
California Department of Fish and Game.1976. A proposal for sea otter protection and research and request for the return of management to the
, State of California. Vol. I: Text and Summaries, California Department of Fish and Game, Operational Research Branch, Socramento, California, 271 PP-B-82-408 5-1
( ; Corroll, J. C. 1982. Seasonal abundance, size composition, and growth of rock crab, Concer antennarius Stimpson, off centrol California. J. Crust. Biol.
j 2(4):549-561.
4-Cox, K. W.1960. Review of the abalone in California. Calif. Fish and Game 46:
381-406.
, 1962. California abalones, family Haliotidae. Calif. Dept. Fish and Game. Fish Bull. I18. I13 pp.
- Cubit, J. P. 1974. Interactions of seasonally changing physical factors and grazing affecting high intertidal communities on a rocky shore. Ph.D.
Diss., Univ. Oregon.122 pp.
Darby, R. L.1964. On growth and longevity in Tegula funebralis (Mollusco, Gastropoda). Veliger 6 (Suppl): 6-7.
I Dayton, P. K.1971. Competition, disturbance and community organization: the provision and subsequent utilization of space in the rocky intertidal community. Ecol. Monog. 41: 351-389.
DeMartini, E. 1976. The adoptive . significance of territoriotity and egg canabolism in the pointed greenling. Ph.D. Diss., Univ. of Wash.,286 pp.
Drummond-Dovis, N. C., K. H. Mann, and R. A. Pottle.1982. Some estimates of
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