\ GULF RESEARCH REPORTS Vol. 9 No. 2 January 1995 ISSN: 0072-9027 Published by the GULF COAST RESEARCH LABORATORY Ocean Springs, Mississippi Gulf Research Reports Volume 9 | Issue 2 January 1995 Estimates of Harvest Potential and Distribution of the Deep Sea Red Crab^ Chaceon quinquedens, in the North Central Gulf of Mexico Richard Waller Gulf Coast Research Laboratory Harriet Perry Gulf Coast Research Laboratory , Harriet.Perry^usm.edu Christine Trigg Gulf Coast Research Laboratory James McBee Gulf Coast Research Laboratory Robert Erdman Florida Institute of Oceanography et al DOI: 10.18785/grr.0902.01 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Waller, R., H. Perry, C. Trigg, J. McBee, R. Erdman and N. Blake. 1995. Estimates of Harvest Potential and Distribution of the Deep Sea Red Crab, Chaceon quinquedens, in the North Central Gulf of Mexico. Gulf Research Reports 9 (2); 75-84. Retrieved from http:// aquila.usm.edu/gcr/vol9/iss2/ 1 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 9, No. 2, 75-84, 1995 Manuscript received Septeoiber 13, 1994; accepted November 14, 1994 ESTIMATES OF HARVEST POTENTIAL AND DISTRIBUTION OF THE DEEP SEA RED CRAB, CHACEON QUINQUEDENS, IN THE NORTHCENTR AL GULF OF MEXICO Richard WallerS Harriet PerryS Christine Trigg^ James McBee^RobertErdnian^ and Norman Blake^ ’Gulf Coast Research Laboratory, P.0, Bax 7000, Ocean Springs, Mississippi 39566-7000. USA ^Florida Institute of Oceanography, 830 1st Street S., St. Petersburg, Florida 33701, USA ^University of South Florida. 830 1st Street S.. St. Petersburg, Florida 33701, USA ABSTRACT Harvest potential, relative abundance, and geographic and bathymetric distribution are discussed for the red crab, Chaceon quinquedens, in the northcentral Gulf of Mexico. Harvest potential is expressed as the numbo- of trapable crabs present on fishing grounds defined as depths ranging from 677 m to 1043 m between 87.5® and 88.5®W longitude. Using various estimates of the effective fishing area (EFA) of a trap, the number of trapable red crabs on the fishing grounds ranged from 3.7 x 10‘ to 10.7 x 10*. Estimates of crab numbers suggest there is a potential for commercial harvest in the northcentral Gulf of Mexico, east of the Mississippi River. However, fishery development must take into consideration the preponderance of females on the defined fishing grounds (M: F ratio = 1:2.1) and the high incidence of ovigerous females (-20%) during much of the year. Females generally dominated at all depth strata, but the proportion of males to females increased with depth. Reduced numbers of red crabs were collected off the western Louisiana coast and a shift in depth distribution was found. Minimum upper depth limit for red crabs west of the Mississippi River was 860 m as compared to 677 m east of the River. The known range of C.fermeri is extended to 92®12''W longitude. Introduction Deep-water crabs of the family Geryonidae are distributed worldwide. Manning and Holthuis (1989) revised the family to include two new genera and nine new species. The majority of geryonid species were placed in the genus Chaceon, The genus Geryon was restricted to two species, G. longipes and G. trispinosus, both from the northeastern Atlantic Ocean, Deep-water fisheries for geryonid crabs are conducted along both sides of the Atlantic Ocean. Eastern Atlantic fisheries for C. maritae exist off Namibia in southwest Africa (Melville-SmiUi 1988), and commercially exploitable quantities of C. maritae are found off the Ivory Coast, Congo, and Angola (Beyers and Wilke 1980). In the western Atlantic, a fishery for C. quinquedens was initiated in the northeastern United States in 1973 and 1974 (OanzandHerrmaim 1975). In 1980, the catch from this fishery was 2500 metric tons (Lux et al. 1982). Other western Atlantic species of Chaceon supporting limited commCTCialfisheries include C. inghami off Bermuda (Luckhurst 1986; Manning and Holthuis 1986) and C.fenneri off Fort Lauderdale, Florida (Erdman and Blake 1988). Faunal surveys conducted by the National Marine FisheriesService (Mississippi Laboratories) andPequegnat (1970) suggest that geryonid crabs are widely distributed throughout the Gulf of Mexico. Lockhart et al. (1990) identified seasonal, geographic , andbaUiymetric distribution of C. fenneri and C. quinquedens in the eastern Gulf of Mexico. Red crabs occurred across the geographic arc sampled, with overall population densities and relative proportion of females highest in the northcentral Gulf of Mexico. Distribution of red crabs in this study was not explained by bottom type, temperature, or interspecific competition, and it was suggested that observed distributional patterns of Chaceon in the eastern Gulf of Mexico may be tied toreproducti ve strategies. Based on the fiming of larval release (Erdman and Blake 1988; Erdman et al. 1991; Perry et al. 1991) and the conceniration of females in the northward portion of the study range, a causal role for the Loop Current in red crab population structure was proposed. There has been considerable interest in fishing for deep sea crabs in the Gulf of Mexico. However, efforts at fishery development have been hampered by lack of information on areal and bathymetric distribution patterns and estimates of stock abundance. The present study addresses the distribution, abundance, and harvest potential of C. quinquedens in the northcentral Gulf of Mexico. 75 Waller ETAL. Materials and Methods This study was designed to establish the geographic and bathymetric limits of Chaceon species and to detennine their relative abundance from 88® to 93®W longitude. Cruises were made in May and August 1989 onboard the Gulf Coast Research Laboratory's 29.7 m steel-hulled research vesseL the RA^ Tommy Munro. Five areas (1, 6- 9) were selected for sampling (Figure 1, Table 1). Area 1 was also sampled by Lockhartetal. (1990). Trap lines were deployed at three selected depths on the day of arrival in an area and were retrieved the following day. Sample depth was varied between the spring and summer cruises to cover bathymetric distributions of C.fenneri and C. quinquedens as repotted by Pequegnat ( 1970) and Lockhartetal. (1990). Depths sampled m May were 494, 677, and 860 m in all areas. In August, traps were set at 3 1 1 , 860, and 1043 m in all areas, with the exception of Area I where traps were set at 860, 1043, and 1830m. The single set at 1830m in Area I was an exploratory set to examine the lower depth limit of red crabs and was not used in statistical analyses of catch d at ^ r Sampling protocol was similar to that followed by Lockhart et al. ( 1990) with the exception that limited deck space necessitated use of the smaller, stackable Fathoms- Plus® ffap in addition to the Nielsendesigned trap (Erdman and Blake 1988). Seven Fathoms-PIus® plastic traps and a single Nielsen trap were fished at each depth within an area. Traps were baited with mixed fidi {Peprilus burtU Gulf buttcrlish; Micropogonias undulafus, Atlantic croaker; Brevoortia pair onus. Gulf menhaden). Trap lines were set ® Does not imply endorsement and retrieved using a hydraulic net reel with a 1.2 m by L5m spool and stem-mounted hydraulic A-frame. Traps were attached to a groundline of 1 .6 cm polypropylene, 732 m in length. Beckets were spliced at intervals of 92 m for attachment of traps fished on 2m gangions. Anchens (23 kg) were attached at both ends of the groundline. A buoyline of 1 .3 cm polydacIon^ylon was deployed at one end of the trap Une at a scope of 3.5 times the depth. Traps were set with the vessel under power during deployment of both groundline and buoyline to ensure proper spacing between traps along the prcdeteimined depth contour. Fishing duration ranged from 18 to 22 hours. On retrieval of the trap line, contents of each trap were separated into species and thecrabs wereplaced innumbeied baskets in chilled seawater. Sex and carapace width (mm) were deteimined forall individuals. Females were examined for presence of eggs or egg remnants, and egg mass color was noted. Bottom water temperatures were measured at each trap site with a reversing thermometer. The effective fishing areaper trap (EFA) was calculated using the method of Miller ( W5) which assumed thateach trap fished a circular area with a radius of one half the distance between adjacent traps. In calculations of EFA of a trap, it is assumed that all traps fish the same, i.e. that there are no significam differences (alpha = 0.05) among the catch/trap along the trap line. To lest this hypothesis, the catch/trap of all traps wa.s statistically analyzed using one-way ANOVAandamuItipIerangeiest(Duncan’sraelhod). An estimate of the number of trapable crabs on the fishing grounds of the northccnlral Gulf of Mexico was calculated using the fomiula provided by McElnuui and Elner (1982): #trapaWe = 1 x meonttcraba x fishing grounds (km®) crabs EFA (km^Arap) trap as* sr M’ as* M* as* v ar to* as* n* sr se* ss* 64* 63* 82* tv to* tb* Figure 1. Location of sampling areas and fishing grounds (shaded area). 76 Red Crab Harvest Potential TABLE 1 Station locations by area, depth, latitude and longitude. Area Depth (m) Latitude CN) Longitude (°W) 1 494 88" 23.00 , 29° 03.73 1 677 88" 24.64 29° 00.59 1 860 88° 19.27 28° 59.67 1 1043 88° 19.23 28° 56.02 1 1830 88° 08.59 28° 44.08 6 311 90° 00.01 28° 06.50 6 494 89° 56.83 27° 58.50 6 677 89° 55.88 27° 56.25 6 860 89° 54.74 27° 53.86 6 1043 89°51.39 27° 47.95 7 311 91° 22.71 27° 50.59 7 494 91° 18.38 27° 47.82 7 677 91°21.18 27° 44.71 7 860 91°23.84 27° 43.20 7 1043 9r25.80 27° 36.56 8 311 92° 04.52 27° 47.78 8 494 92° 11.89 27° 39.98 8 677 92° 12.39 27° 37.65 8 860 92° 13.99 27° 35.44 8 1043 92° 08.77 27° 33.39 9 311 93°02.21 27° 39. 15 9 494 93°07.77 27° 33.29 9 677 93° 03.00 27° 32.88 9 860 93° 00.11 27°29.16 9 1043 93°08.12 27° 22.58 Fishing grounds were detined using red crab distribution and abundance data from Lockhart ei al. (1990) and the present study. Fishing grounds were located at depths from 677 to 1043 m between 87.5® and 88.5®W longitude and encompassed approximately 1200 km^. Male to female abundance by trap set, catch/trap by depth, and catch/trs^ by season were statistically analyzed by apaired comparison of difference in abundance. Results are reported using a t-statistic with alpha set at 0.05. C^arapace width of males and females was compared using a two sample analysis of means assuming unequal vaiiances(t-test,alpha=0,05).Peicenlofcalchof commercial size was determined for males and females by area. Results Temperature Bottom water temperatures within depth strata ranged from 1 1.4 to 12.7®C at 311 m, 8.0 to 8.8®C at 494 m, 6.4 to 7.2®C at 677 m. 5.6 to 6.0®C at 860 m, and 5.2 to 5.6®C at 1043 m. Temperature was not taken at the deepest depth sampled, 1830 m. Bottom water temperatures decreased with depth, and the range in temperature within a depth stratum narrowed with increasing depth. In May, for stations west of the Mississippi River, temperatures tended to increase from east to west within the 494 and 677 depth strata. Comparative seasonal daiaareavailableonlyforthe 77 Waller ET AL. 860 m sampling depth, and there was little difference in the temperature extremes between May (5.6 to 6.0°C) and August (5.8 to 6.0°Q. Distribution Studies Carapace width (CW), sex, male to female ratio, and bathymetric distributions by area and season were recorded for C. quinquedens (Table 2). Mean carapace width per trap set ranged from 109 to 140 mm for females and 95 to 143 mm for males. Smallest crabs occurred in deeper depths west of the Mississippi River in Areas 8 and 9. Overall mean carapace width of males (128 mm) was significantly different from the mean carapace width of females (1 16 mm), (P = 0.00, t = 1.97 at 458 df). Total number of male and female crabs and total number of crabs > 1 14 mm CW (minimum size for harvest in the Atlantic fisheiy as reported by Annstrong 1990) were determined (Figure 2). In Area 1, east of the Mississippi River, 99% ofmales and 61% of females were>114mmCW. Combining all areas, 87% of the males and 63% of females were of commercial size, with 81% of all crabs >114 mm CW regardless of sex. Areas 1 and 9 produced 65% and 17% of the red crabs taken, respectively (Figure 3). Contribution to total catch was between 3% and 7% for all other areas (6-8). Average catch/trap set by sex at all areas, depths, and seasons in sets where crabs were caught was used to compare abundance of males versus females. There was a signiricant difference in the mean number of males to females per trap set (P = 0.02, t = 2.57 at 17 df). Mean number of males per trap set was 18.2, compared to 38 .6 for females. The ratio of males to females varied from 0: 1 .0 to 1,0:32 among trap sets (Table 2), with females twice as abundant as males overall (M:F = 1. 0:2.1). Bathymetric distribution as a function of mean catch/tr^ by area and season is shown in Tables 3 and 4. The highest overall mean catch/trap was 23,8 crabs at 677 m in May at Area 1 . With the exception of the shallowest depth (494 m, n = 1), mean catch/trap in Area 1 was not significantly different between sampled depth strata for May ( x = 23.8 at677mandx= 16.9at860m)orAugust(x=20,9at860mand X = 19.3 at 1043 m). Catch/trap for Area 6 was not statistically compared between seasons due to lost trap lines. Mean catch/trap for Areas 7. 8, and 9 was compared between 860 m and 1043 m depths for August. In Area 7, there was no significant difference in mean caich/trap at 860 m ( X = 2.8) and 1043 m ( x = 2.6). For Area 8, mean catcli/trap was significantly greater at 1043 m (T = 6,6) than at 860 m ( x = 1.6; P = 0.00, t = 4.61 at 7 df). The reverse was true for Area 9; there was a significantly higher catch/trap at 860 m than at 1043 m (P = 0.0 1 , t = 3.90 at 7 df). Mean catch/trap at 860 m was 9.6, compared to 3.9 crabs at 1043 m. Catch/trap was used to compare seasonality of catchat the common depth of 860m ateacharea. No significant difference in mean catch/trg^ were found at any area between May and August at 860 m. Upper depth limit of red crabs west of the Mississippi River (Areas 6-9) was 860 m, compared to 677 m for crabs taken in Area 1 , east of the River. Catches of a single crab at 494 m in Area 1 and at 677 m in Area 7 were considered solitary events and were not used in defining the observed upper depth limit. Recent oviposition in C. quinquedens is indicated by the presence of orange egg masses; eggs become purple- black prior to hatching (Haefiier 1 977). Seventeen percent of all females collected in May were ovigerous, with either orange or brown egg masses. Egg remnants were recorded on the pleopods of 11 individuals. Ovigerous females collected in August comprised 18% of all females. Egg colors were predominantly brown, and no egg renmants were observed. Ovigerous females were more abundant at the shallower depths of their bathymetric distribution (677 and 860m). The size range of ovigerous females in August (95- 1 35 mm CW) was comparable to those collected during May(l(X)-130mmCW). One immature female crab (64 mm CW) was taken at 860 m in May in Area 6. A comparison among catch/trap by trap number was performed with one-way ANOVAand a multiple range test (Duncan’s method). These tests were applied over all areas, depths, and seasons in sets where crabs were caught. The mean catch of end traps (traps 1 and 8) was 7.0 and 9.6, respectively, compared to the mean catch of inner traps (traps 2 through 7, "x range = 6. 1 to 1 1 .3). The Nielsen trap had the highest mean caich/trap ( x = 1 1 .3) due to two high catches in Area 1. Statistically significant differences in mean catch were not found among crab traps (ANOVA). Catch was found to be homogeneous among traps (multiple range test). The EFA/trap was calculated to be 6,647 m^ Based on the formulas of McElman and Elner (1982) and Miller (1975), the estimated number of trapable red crabs was extrapolated to be 3.7 x 10® on a calculated fishing ground of 1,200 km^. Chaceonfenneri was not abundant in the study area, (jolden crabs occurred in samples in May. Four specimens were taken in Area 6 (3 at 494 m, 1 at 677 m). Areas 7 and 8 each produced a .single crab at 494 m. 78 Red Crab Harvest Potential TABLE 2 Summary of catch data of Chaceon quinquedens in the northcentral Gulf of Mexico. Date Area Males Females Total No. Ratio M/F Carapace Width Carapace Wic^ No. Depth Meters Mean Max. Min. No. Mean Max. Min. 05/15/89 1 494 0 130 130 130 1 1 0:1 05/15/89 1 677 133 147 122 42 116 144 93 148 190 1:3.5 05/15/89 1 860 132 145 108 45 114 133 95 90 135 1:2 05/13/89 6 494 0 0 0 05/13/89 6 677 0 0 0 05/13/89 6 860 143 143 143 1 120 140 64 10 11 1:10 05/13/89 7 494 0 0 0 05/11/89 7 677 0 140 140 140 1 1 0:1 05/11/89 7 860 140 140 140 1 128 139 110 28 29 1:28 05/09/89 8 494 0 0 0 05/09/89 8 677 0 0 0 05/09/89 8 860 0 118 125 112 6 6 0:6 05/07/89 9 494 0 0 0 05/07/89 9 677 0 0 0 05/07/89 9 860 130 136 125 2 114 135 98 64 1:32 08/12/89 1 860 134 148 123 61 115 137 95 106 167 1:1.7 08A2/89 1 1043 132 147 118 98 114 132 94 56 154 1.8:1 08/14/89 1 1830 127 133 123 3 114 123 103 16 19 1:5.3 08A0/89 6 311* 08A(y89 6 860* 08/10/89 6 1043 129 140 120 8 118 132 102 18 26 1:2.3 08/08/89 7 311 0 0 08/08/89 7 860 138 141 136 5 129 142 114 17 22 1:3.4 08/08/89 7 1043 139 151 127 2 126 137 117 19 21 1:9.5 08/06/89 8 311 0 0 08/06/89 8 860 135 140 130 2 130 142 109 11 13 1:5.5 08/06/89 8 1043 95 137 eh 40 109 131 76 13 53 3.1:1 08/04/89 9 311 0 0 08/04/89 9 860 125 144 89 9 111 127 92 68 77 1:7.6 08/D4/89 9 1043 120 139 95 8 110 131 85 23 31 1:2.9 ♦ Trap line lost 79 Waller ET al. Number of Males Area 1 Area 6 Area 7 Area 8 Area 9 Total Number Commercial Size Number of Females Area 1 Area 6 Area 7 Area 8 Area 9 Total Number Commercial Size Figure 2. Total number of male and female Chaceon quinquedens ^114 mm carapace width. 80 Red Crab Harvest Potential PERCENT Figure 3. Percent catch, Chaceon quinquedenSf by area. Discussion Bathymetric and Geographic Distribation Previous reports of geryonid crabs in the Gulf of Mexico include references to two species. Data from trawl surveys contain records of C. quinquedens and C. affinis (NMFS, Mississippi Laboratories). Pequcgnat (1970) recorded C. quinquedens in the northern Gulf of Mexico and in the Caribbean. With the recognition and description of CJenneri from slope waters of the western Atlantic and Gulf of Mexico, it is probable that early accounts of C. affinis from the eastern Gulf of Mexico are referable to C. fenneri (Manning and Holthuis 1984). Otwell etal. (1984) foimd C. fenneri common in the Gulf of Mexico at depths ranging from 384 to 641 m within latitudes 29^03' and 26®50' and longitudes 84°50’ and 85°32'. Lockhart el al, (1990) described the distribution of red and golden crabs in the eastern Gulf of Mexico and noted that there were geographic and bathymetric differences in distribution and abundance. They found red crabs widely distributed in the eastern Gulf of Mexico at depths of 677 m, their deepest sampling depth and the upper limit of red crab distribution. Highest concentrations were found in the norihcentral Gulf of Mexico between 87.5 and 88.5°W longitude. A supplemental sample taken during their study found red crabs at 900 m in that area. Golden crabs were more restricted in geographic distribution, with abundance centeredinslopewaiersbelow28®Nlatitude. Theyoccuned at all depths sampled, but were most abundant at the shallower depths (311 and 494 m). Golden crabs were not abundant in our study (n = 6); thus geographic and bathymetric data are limited. Based on our samples, the known range of C. fenneri is extended to the western Gulf of Mexico (92®12"W longitude). Bathymetric distribution of red crabs differed east and west of the Mississippi River. Red crabs were taken consistently at the 677 m sampling depth in the eastern Gulf of Mexico. However, the upper depth limit for red crabs west of the Mississippi River was 860 m. Although there was a downward shift in bathymetric distribution west of the River and different depth strata were sampled in May and August, a differential distribution by sex and depth was observed. While females outnumbered males at most depths sampled (two exceptions), the proportion of males to females increased at deeper depths. Approximately the same number of individuals weie taken at the 860 and 1043 m sampling depths west of the River, indicating that deeper 81 TABLE 3 Catch per trap by area and depth for May 1989 Waller ETAL. ooooooooo§§§ o o c> 000000000888 O O 00 o-icniNoooo\otGSS2 d — ^ 000000000888 odd 000 000000000SS8 d d d oooooooooSlS 000 '^OOOOOOO^^mS odd S'S'S’S'S'&'&S' e fi A e fl fi e I I 5 ^ ^ ^ s II oodoooooo tn'o2S5 cn-H-^ooonvo^ 000000000 CSO-ilO^114 nun CW) taken in this study. These rates are also comparable to the highest rates reported by Wenner et al. (1987) for golden crabs in the South Atlantic Bight off South Carolina. Estimates of red crab population densities derived ffom trap studies were made by Stone and Bailey (1980) and McElman and Elner (1982) along the Scotian Shelf. Us'mg a study area of 2767 km^ Stone and Bailey (1980) projected population densities of 2.3 x 10^^. McElman and Elner (1982) provided various population estimates for their study area based on changing EFAs. Lowest estimates usedanEFAof4,100m^toproduce2.8x 10® crabs. Highest population estimates were based on an EFA of 2300 which produced an estimate of 5 x 10® crabs. Because greater catches at end traps did not occur in their studies, these authors suggested that there was no overlap in fishing area in traps placed 54 m (Stone and Bailey 1980) and 62 m apart (McElman and Elner 1982). They noted that density and biomass estimates were best based on an EFA of 2300m^ Using an EFA of 6647 m^ we calculated minimum crab densities of 3.7 x 10® on the northcentral Gulf of Mexico fishing grounds. If we assume an EFA of 2300 for the total calculated fishing grounds (1200 km^), our estimate of population size would increase to 10.7 x 10® crabs. An inteimediate EFA of 3000 m^ would produce a population estimate of 8. 1 x 10® crabs. Based on these catch rates, the red crab in our calculated area could potentially support a small commercial fishery. Fishery development, however, must take into consideration the preponderance of females on the fishing grounds (M;F ratio 1 :2.1) and the incidence of ovigerous females (-20%) during much of the year (Lockhart et al. 1990 and present study). In addition, data on recniimieni to fishing grounds as well as infoimation on critical life liistory parameters are necessary before fishery development Ls encouraged. 83 Waller ET AL. Acknowledgments Support for this project was provided by USEKXI/ NOAA/NMFS MARFIN Grant No. NA89WC-H-MF021. We thank the crew of the RA*" Tommy Munro for their ability to adapt to any situation and to endure the long hours of boredom foUowedbyperiodsof intense activity associated with deep-water biological sampling. We also thank Dennis Koi who supplied the computer program used to develop Figure 1 and David Donaldson who assisted with graphics. MaijorieWilliamsaidedinnianuscripiprepaiation. Special flianks to flie Universily of Georgia, SeaGrantExtesnsion Service, Brunswick Laboratory, for supplying the Fathoms Plus tr^ used in this study. Exploratory fishing data (NMFS, MissassippiLaboratories) wassuppliedby BennieRohrand the late Elmer Guthens. We tue appreciative to the late Dr. Harold Howse, direcioremeritusof theGulf CoastReseaichLaboiatoiy, for his support of this project. LrrERATCRE CrrED Armstrong, D.A. 1990. Commentary on crab management and the east coast United States geryonid fisheries, in: W.J. Lindberg and E.L, Wenner (cds.), Geryonid Crabs and Associated Continental Slope Fauna, Workshop Report, p 23-29. Fla Sea Grant Coll Program Tech Pap 58. Beyers, C.J. and G.G. Wilke. 1980. Quantitative stock survey and some biological and morphometric characteristics of the deep-sea red crab Geryon quinquedens off southwest Africa. Fish Bull S Afr 13:9-19. Cooper, C. and A.H. Humphreys,!!!. 198 1 . Circulation study of the western Florida Shelf. 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Fish Bull 85(3):547-560. 84 Gulf Research Reports Volume 9 | Issue 2 January 1995 Observations on Extant Populations of the Softshell Clam^ Mya arenaria Linne^ 1758 (Bivalvia: Myidae)^ from Georgia (USA) Estuarine Habitats Erik Rasmussen University of Copenhagen Richard W Heard Gulf Coast Research Laboratory, richard.heard^usm.edu DOI: 10.18785/grr.0902.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Rasmussen, E. and R. W. Heard. 1995. Observations on Extant Populations of the Softshell Clam, Mya arenaria Linne, 1758 (Bivalvia: Myidae), from Georgia (USA) Estuarine Habitats. Gulf Research Reports 9 (2): 85-96. Retrieved from http:// aquila.usm.edu/gcr /vol9/iss2/2 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. GulfResearchReports, VoL 9, No. 2, 85-96, 1 995 Manuscript received August 16, 1994; accepted November 25, 1994 OBSERVATIONS ON EXTANT POPULATIONS OF THE SOFTSHELL CLAM, MYA AREN ARIA LINNfi, 1758 (BIVALVIA: MYIDAE), FROM GEORGIA (USA) ESTUARINE HABITATS Erik Rajsmussen^ and Richard W. Heard^ 'Zoological Museum, University of Copenhagen, Universitetsparken 15,DK-2100 Copenhagen 0, Denmark ^Invertebrate Zoology Section, Gulf Coast Research Laboratory, P.O. Box 7000, Ocean Springs. Mississippi 39566-7000, USA ABSTRACT The softshell arenaria Linn6, 1758, is reported from Georgia (USA) estuarinehabitats based on studies conducted between 1969 and 1972. Observations on Georgia estuarine habitats where cxtantpopulations of softshell clams occurred arc described. On several occasions, fresh shells with pcriostracum and tissue remnants were found in a brackish drainage system on Sapelolsland. Thescsheils represent the firstsouthem records of extant populations of softshell clams from such a specialized habitat type. Living specimens oiM. arenaria from the benthos and specimens in the stomach contents of stingrays (Dasyatis sabina) were collected at four stations during 1969 in the North and South Newport Rivers, mcsohaline tidal systems forming part of the southern and northern headwaters of S L Catherines and Sapelo Sounds . The stom ach of a stingray collected near the mouth of Li ttle Ogccchc River during another study also contained specimens of M. arenaria. Ephemeral, intertidal, winter populations of juvenile softshell clams arc reported from exposed pleistocene beach faces along tidal rivers in Chatham, Georgia. Hie associated fauna collected with softshell clams and occurrence of other cold temperateand borealspccies from Georgia estuaries are discussed. The distribution of Af . arenaria appears to be mainly limited by acritical maximum temperature of 28®C, Thcrelatively cooler summer temperatures observed at the Sapelo Island tidal ditch site may enable the species to survive in this restricted habitat. Data from the present study indicate that during winter and spring, softshell clams appear to be bionomically important components of the benthos and the diet of stingrays in some Georgia estuarine habitats. Whether or not reproducing populations of M. arenaria occur year-round in Georgia estuaries still remains an open question. Introduction Between 1 967 and 1 972, we made a series of collections and observations on two estuarine habitats, one associated with tidally influenced brackish water ditches on Sapelo Island, the other in the subtidal upper reaches of St. Catherines and Sapelo Sounds. These two habitats have been generally described in earlier publications dealing with other faunal studies (Sikora et al. 1972; Heard 1975; Rasmussen 1994). At some of the study sites in these two areas, we were able to document the presence of extant populations of the softshell clam, Mya arenaria Linn6. 1758, a commercially important bivalve (Hanks 1 963; Rleggi and Thompson 1979) commonly known to northern temperate and boreal coastal habitats of Europe and North America (Theroux and Wigley 1983). Historical Mya arenaria has existed along the North American and European coasts since the Pliocene, but died out in Europe during the Ice Age at the beginning of the Pleistocene (Strauch 1972), after which it later became reestablished. Since the larvae could not have spread spontaneously to Europe from America, it was previously assumed that M. arenaria was reintroduced to Europe by man in the 16th century after the voyage of Columbus (Hessland 1946). Recent findings by Danish geologists, however, imply a reestablishment of the species in Europe much earlier, about 1200, probably by Viking voyagers. This is supported by carbon-dated analyses of shell material of M. arenaria from Holocene layers in the Kattegat region, Jutland (Petersen et al.l992). Extant populations of Mya arenaria are presently known or reported from most of western Europe, from the East Coast of the United States (Labrador to Charleston, South Carolina), from isolated populations in the Arctic, and from introduced populations established along the Pacific coast of North America (Foster 1946; La Roeque 1953; Gckelmann 1958; Tebble 1966;Laursen 1966; Abbott 1968, 1974; Emerson et al. 1976; Bernard 1979; Theroux and Wigley 1983; Abbott and Dance 1986). Because of its broad range in the northern hemisphere, various authors have placed the softshell clam in the following six zoogeographical faunal provinces: Virginian, Boreal, Celtic, TYansatlantic, AleutianCalifomian, 85 Rasmussen and Heard and Japonic (Coomans 1962; Gosner 1971; Dance 1974). None of these authors, however, mention the occurrence of Af. arenaria in the Carolinian Province. Records of softshell clams from the Carolinian Province are sparse and vague. According to Foster ( 1 946), the North Carolina record (from Beaufort) is based on dead valves only. Abbott’s (1968) South Carolina record is not documented or repeated in any of his later publications and may be an error. Regarding its North American, East Coast occurrence, Theroux and Wigley (1983: 48) slate, “The normal distribution of the softshell clam is from Labrador to South Carolina, extending, locally, south to Florida..” The record from South Carolina is based on specimens from a population near Charleston; these specimens are housed in the Woods Hole Collections of the National Marine Fisheries Service, However, Theroux and Wigley (1983) cite no published or unpublished references to specimens or collection sites for the occurrence of softshell clams in Florida waters. There are several nominal published records for My a arenaria from Georgia estuarine waters. Two of these records are only mentioned in footnotes (Sikora et al. 1972:518; Howard et al . 1 97 3:43). Howard and Frey ( 1 97 5a) reproduced Heard and Heard’s (1971) unpublished list of the common invertebrates of Sapelo and St. Catherines Sounds which included records of softshell clams from the mesohaline waters of the North Newport River system. Extant specimens of M. arenaria were listed from the Turtle River (St. Simmons Sound) and St. Marys River (Florida- Georgia border) by Howard and Frey (1975b) and from Doboy Sound by Mayou and Howard (1975). Frey et al. (1975:271) reported softshell clams from tidal river channels throughout the Georgia coast and considered this bivalve as one of several “best indicators of present-day estuarine environments in Georgia.” Later, Howard et al. (1977:341) briefly mentioned the presence of A/, arenaria in the diet of stingrays from Georgia estuaries. Materials and Methods Sapelo Island Collection Sites Sapelo Island is located off the coast of Georgia (Figure 1). The island study site was in a brackish-water drainage ditch under High Point Road (culvert then present). This ditch is part of the head waters of Bam Creek, which empties into the Duplin River, a northeastern arm of Doboy Sound, about 800m NNW of the Sapelo Island air field (Figure 2). The general ecological characteristics of the tidal ditch habitats in this area have been described earlier by Rasmussen ( 1 994). The collection site is located in an isolated area surrounded and shaded by a dense, mixed hardwood-pine forest. The water level was influenced by regular tides from the Duplin River. On the landward side of the ditch, the often strong currents through the culyerthad created apool, approximately one meter deep, with a relatively firm bottom where the shell material of Mya arenaria was collected. The site was visually inspected weekly from early June 1971 to early February 1972. Any changes were noted and any visible shells were collected by hand or with a dipnet. Water temperature was measured with amercury thermometer and salinity was measured witha T/C refractometer (American Optical Corporation). Both measurements were taken just below the surface. An attempt was initially made to obtain sediment samples, but it was impossible to dig in the hard substratum. North Newport River Collectioii Sites (Figure 3) Specimens of Mya arenaria from this area were collected in 1 969 during abaseline study to monitor possible ecological effects of a paper mill on Riceburro Creek, a headwater tributary of St. Catherines and Sapelo Sounds. Faunal and water-quality data (dissolved oxygen (DO), pH, salinity, temperature, turbidity) were gathered during 43 monthly cruises using the University of Georgia Marine Institute research vessel, R/V Kit Jones. The faunal collections were made monthly at 14 stations in Sapelo Sound, St, Catherines Sound and their adjacent tidal river tributaries OPigure 3), Four of these stations (10, 11, 12, and 13), all located in the head waters of Sapelo and St. Catherines Sounds (North and South Newport River systems), are relevant to this study. Stations 10, 1 1, 12, and 13 were sampled along a 300 to 400 m track in or immediately adjacent to the river channel in depths ranging from 4 to 8 m. Stations 10, 12, and 13 had a mostly sand-silt substratum. Station 1 1 had a mosaic of bottom types ranging from coarse gravel with fossil lag deposits (sharks teeth, whale bone, etc.) to mixed sand-silt and hard mud substrata. The channel margins along some or all parts of these station tracks were composed of consolidated pleistocene sand deposits. Fish and large cpibenthic invertebrates were collected with a 25-foot otter trawl, infaunal macroinvertebrates with a bucket dredge. Samples of the latter comprised all fauna retained by a 1 mm screen. A series of fish specimens from each station were kept for stomach-content analyses. Apart from a few voucher specimens and the fish for stomach- 86 Extant Populations of Mya arenaria Linn6 from Georgia Estuaries Figure 1. Map of Sapelo Island, Georgia, showing location on US East Coast (inset, lower right) and location of study area (fk-amed, see Figure 2). 87 Rasmussen and Heard Figure 2. Enlarged map of study area on Sapelo Island, showing Duplin River, Bam Creek and Post Office Creek, leading to locality with Mya arenaria (circled). Depths in feet. Map from Doboy Sound, GA. N3122-W81 15/7.5. US E>epartment of Commerce Coast and Geodetic Survey, edited and published by the US Geological Survey, 1954. content analyses, most fish and large macroinvertebrates Representative specimens of Mydarenanacollectedduring were identified and counted while alive, then thrown this study with the bucket dredge are d^osited in the National overboard. All fish and sieve residues retained were fixed Miseum of Natural History (USNM), the 2^1ogicaI Museum, onboard in a 4% solution of formaldehyde in seawater, later Universityof Copenhagen(ZMUQ, andtheOulf CoastRcsearch washed in freshwater and transferred to 70% ethanol. Laboratory Mu.seura(quality data (from Sikora et al. 1972). Results and Observations strong currents at high tide. The largest number of shells was found on 6 December, shortly after a strong storm on 2-3 Sapelo Island December which raised the normal sea level over a meter. Water temperatures at the time of sampling ranged from high A total of nine shell pairs and 25 single valves of Mya averages of 26.0-27 .4®C in summer to low averages of 13.4- arenaria were found on seven occasions from July to 16.4®C in winter. Salinity ranged from 20-26?/oo in June and December 1971 (Table 1) at the High Point River culvert Dec«nber to occasional lows of 3-57«>o in August and in site. All shells were thin and fragile. Although no living January-February which were associated with heavy local specimens were obtained, all shells had fresh periostracum. rainfall. The allached tissue remnants on a few of the valves suggested Despite careful and regular searches during the senior that the living clams had been eaten by crabs, birds, or author’s stay on Sapelo Island, no living specimens of Mya raccoons. The thin shells may be a result of life under less arenana were found along the more open mud bars, than optimal conditions for the species. All shells were beaches and sandy shallows of the island. Only a single found on the bottom of the pool on the landward side of the valve of a dead and worn specimen, perhaps a fossil, 66 mm culvert and probably were washed in from the marsh by the long, was found washed ashore on the open Atlantic beach. 89 Rasmussen and Heard TABLE 1 Mya arenaria from Sapelo Island* Georgia, Shells and attached shell pairs found in 1971. Shell length expressed as average (minimum-maximum); for averages* each shell pair counted as one unit. Date in 1971 Shell Pairs Single Shells Shell Length (mm) 9 July 2 __ 29 (23-35) 8 Septembo* 1 - 48 9 Novanber 1 3 36.5 (34-39) 22 November ~ 2 37 (36-38) 6 December 4 9 left, 5 right 40.7 (26-55) 20 December ~ 2 right 35.5 (29-42) 27 December 1 3 left, 1 right 37.4 (30-47) Gf the many ditch and creek habitats of the island examined in 1 97 1 , only the above locality contained material of Mya arenaria in the form of fresh shells, some with tissue remnants. An attempt was also made to sample the Spartina marsh downstream from the drainage culvert, but the dense tangle of blades and rhizomes combined with the very soft mud made it nearly impossible to dig there. No living clams or recent shells were found. Since the possible uniqueness of this drainage ditch habitat was not known to us at the time, no further efforts were made to find living specimens. We did not have an opportunity to collect in the channel bottoms of the adjacent tidal creeks (Post Office and Bam Creeks) on Sapelo Island where sand-silt substrata are present some sections of their runs. In future studies, such creek-bottom habitats should be sampled seasonally with cores, yabby pumps (hand-held suction devices), or small water-jet pumps to determine if softshell clams are present. North Newport River Our observations on North Newport River populations of Mya arenaria represent an expansion of the data presented in an unpublished final report by Heard and Heard (1971). In that study, which dealt with an ecological evaluation of the invertebrate communities in St. Catherines and Sapelo Sounds and their respective tidal river tributaries, M. arenaria was reported in bucket-dredge samples taken at three stations on eight different occasions. Softshell clams were r^orted at stations 10 and 1 1 from the middle, mesohaline reaches of the North Newport River during winter and spring (February to June) of 1969 (Table 2). With the exception of salinity-temperature-DO measurements, neither Heard and Heard (1971) nor another unpublished companion report by Dalhberg (1971) presented exact information about depth and bottom conditions or the size and quantity of animals, whose occurrence was simply designated as “present,” “common,” or “abundant”. We are now able to present additional information on the populations of Mya arenaria collected from the North Newport and South Newport River systems during the 1967-1971 paper mill environmental impact study, but not included in Heard and Heard (1971). This information includes additional environmental data on the stations where softshell clams occurred, records from Station 12 (Table 2), and data on M. arenaria from the stomach contents rays and hakes. During the five-month period in which Mya arenaria was present in the samples (10 February-2 June), temperatures at stations 10, 11, and 12 were lowest on 6 March (lO.S^C at 10 and 1 1, 10.7°C at 12) and highest on 2 June(29.4®C,28.1®C,and28.3«Cat 10, 1 l,and 12, respectively). Salinities for stations 10, 11, and 12 were lowest on 1 April (15.77oo, 12.47oa, and 15.37oo) and highest on 10 February (23.47oo, 23.67oo, and 25.47w, respectively). During the winter and spring of 1969, specimens of Mya arenaria were taken twice at station 10 (“present” in March and May) and five times at station 11 (“common” in February and April, “present” the other three months), and once at station 12 (station 1 2 not included in Heard and Heard 1971). Regrettably, most of the specimens of Mya arenaria reported in Heard and Heard (1971) are now unavailable for study. However, voucher specimens for four of these eight North Newport River collections are extant. Stations, collection dates, and measurements for these voucher specimens are presented in Table 2. 90 Extant Populations of Mya arenaria Linn6 from Georgia Estuaries TABLE 2 Occurrence of Mya arenaria collected with a bucket dredge from the North Newport River at stations 10 and 11 during March, April, May, and June 1969 (from Heard and Heard 1971), plus data from station 12 and from voucher specimens. Length measurements in mm for available voucher specimens. Station (Cruise) Date (1969) No. of Clams ' Shell length mm* 10 (33) 1 April present unknown 10 (35) 2 June present unknown 11 (31) 10 February (6) common 16.7 (14.2-20.6) 11 (32) 6 March (8) present 17.7 (11-23.2) 11 (33) 1 April (4) present 16.9 (14.2-20.6) 11 (34) 1 May present unknown 11 (35) 2 June present unknown 12 (32) 6 March (2) 15.1 (8.1-22.1) ♦Based on range and average of voucher specimens (number of voucher specimens in parentheses). The voucher specimens from the February, March, and April collections appear to be juveniles and subadults. Based on notes and sketches of the second author, the specimens taken with the bucket dredge at Station 1 1 during June 1969 were distinctly larger than those collected in February and April (R. Heard, impublished observations). These tentative observations are supported by the similar size (40+ mm) of softshell clam specimens taken from the stomachs of Atlantic stingrays collected at this station during the same period. Fauna Associated with North Newport River Mya arenaria Populations A fairly diverse benthic assemblage of macro- invertebrates was associated with spring populations of Mya arenaria in the North Newport River (Heard and Heard 1971). At stations 10. 11, and 12 in depths ranging from 4 to 8 meters, dense populations of the ascidian Mogula manhauensis (DeKay) with associated hydroids, bryozoans {Anguinella palmam van Beneden and Amathia distans Busk) and gammarid amphipods {Gammarus mucronatus Say and Melita nitida Smith) were attached to the consolidated pleistocene deposits along the edges of channels. Other species commonly associated with the pleistocene deposit community were the nereidid polychaete Neanthes succinea (Frey and Leuckart); the hooked mussel Ischadium recurvum (Rafinesque); the false angelwing Petricola pholadiformis Lamark; the common grass shrimp Palaemonetes vulgarus (Say); and the xanthid crab Rhithropanopeus harrisli (Gould). In or on the sand-silt bottom deposits where M. arenaria occurred, three other moUusks were common; the Atlantic paper mussel, Atnygdalum papyrium (Conrad), the dwarf surf clam, Mulinia lateralis (Say), and the brown banded wentletrap, Epitonium rupicola (Kurtz). Populations of the ampbipod Ampelisca abdita Mills, the isopods Cyathura polita Stimpson and Cleantoides plantcauda (Benedict), and the polychaetes Diopatra cuprea Bose and Sabeilaria vugaris Verrill also occurred in or on the same substratum with softshell clams. Georgia Intertidal Populations of Mya arenaria Additional observations on extant populations in Georgia waters were made by one of us (RWH) between 1962 and 1994. Ephemeral, intertidal, winterpopuladons of juvenile Mya arenaria occurred intermittently on exposed pleistocene beach faces along Moon River, a mesohaline tidal river in Chatham, Georgia. In the lower intertidal zone along these shore faces, juvenilesoftshell clams (6- 12 mm in length) were observed in small silt-filled depressions that pocked the consolidated sand-clay shore face. During some winters. 91 Rasmussen and Heard densities often exceeded 250 individuals per It is likely that such ephemeral juvenile “accessory” populations occur at other similar intertidal habits in Georgia estuaries during the winter and early spring. Such juvenile clam populations may be bionomically important in the diets of shore birds. On several occasions during the late winter at the Chatham county site, flocks of small unidentified “sand pipers” were often seen feeding along the lower shore in areas where juvenile soft shell clams were common. Possible Factors Determining the Occurrence of Mya arenaria in Georgia Estuaries Based on our limited observations, Georgia populations of Mya arenaria appear to have restricted habitats, be most common during the winter and spring months, and have shell sizes that do not approach those found in northern softsbell clam populations. Ecological factors, including salinity, food supply, substratum and temperature (Swan 1952a) determine the occurrence, distribution, and size of softshell clams in Georgia estuaries. Salinity. Over the period of this smdy. salinity at the Mya arenaria collection site on Sapelo Island varied from highs of 20-267oo in June and December to occasional lows of 3-5 ®/do in August and in January-February. Since M. arenaria is known to tolerate sudden and considerable changes in salinity (Matthiessen 1960), it is unlikely that the infrequent salinity fluctuations at the S^)elo Island site and those observed in the North and South Newport River systems would be a decisive factor in softshell clam survival. Substratum. Therouxand Wig)ey(1983) found softshell clams to be most common in sand-silt bottoms. S wan ( 1 952b) reported that these clams grow faster in sandy bottoms than in compact mud substrata. The substratum surroundmg the ditch collection site was soft mud or mud permeated with rhizomes of associated marsh grasses. Based on the observations of Swan (1952a), softshell clam growth in this type of habitat may be retarded. This might be one reason why the largest shells examined from the extant population on Sapelo Island (Table 1) were only 4.8 cm long. The largest specimens of Mya arenaria observed from the North and South Newport River systems were taken from stingray stomachs at station 1 1 during June 1969. Like clams from the Sapelo Island site, these clams had maximum valve lengths under 5 cm, even though the bottom sediments in the vicinity of this station were predominantly sand-silt and appeared to be more suitable for growth of softshell clams than the mud bottom at the Sapelo Island site. Food supply. In Georgia habitats, food supply should not be limiting in view of the high primary production throughout the surrounding marsh and estuarine waters (Odum 1961). Odum and de la Cruz (1967), working on S^elo Island, found the amount of organic detritus (2-20 mg ash- free dry organic matter per liter), mainly from Spartina, to be much greater than that reported for the open sea. The nutrient-rich waters of Georgia estuaries support a rich planktonic and benthic diatom flora (Pomeroy et al. 1981) which could be utilized as a food source by local populations of Mya arenaria. Temperature. Mya arenaria is essentially a boreal- cold temperate species with its main distribution in more northern latitudes. Its restricted occurrence in the warm- temperate, estuarine waters of Georgia would be an interesting subject for studies on physiological adaptation. A comparison between the lower temperature conditions at the Sapelo Island drainage site that supported a population of M. arenaria during 1971 and the higher temperature conditions of adjacent marine habitats lacking clam populations may explain this special occurrence. Published hydrograf^ic data from comparable habitats in Georgia coastal waters are mostly limited to hydrograpliic and ecological studies conducted in the sounds and oceanic waters adjacent to Sapelo Island. For comparison with the data from the brackish-water ditch habitats, we utilized physical data collected between 1967 and 1970 from surface waters al station 2 (Figure 3), located in Sapelo Sound off the northern tip of Sapelo Island (Dalhberg 1971). During that study, temperatures ranged from high averages of 28.7- 29.2®C in summer to low averages of 8.8- 1 1 .8®C in winter. In spite of the fragmentary and incomplete data from both localities, these data suggest that overall lower temperatures exist at the drainage ditch site (13.4-1 6.4^C winter lows to 26.0-27 .4®C summer highs) as compared to the open water (i.e., Sapelo Sound site), especially during the summer months. The subtle temperature differences in such specialized habitats that support lower temperatures during the summer months may help support a niche in which softshell clam populations can survive at lower latitudes where they normally would not be expected to survive. High temperatures are reported to be an important limiting factor for softshell clams in southern estuarine habitats (Laursen 1966). Accordingly, well established populations of Mya arenaria normally occur in estuarine and marinehabitats where water temperatures are ermsistendy less than 28®C (Kennedy and Mihursky 1971). In Chesapeake Bay, large-scale mortalities of softshell clams took place whensummertemperatuiesexceeded28®C(Pfitzenmeyer 1972). 92 Extant Populations of Mya arenaria Linn^ from Georgia Estuaries Temperature may also control the size of southern softshell clam populations. The observed small size of Mya arenaria specimens from Georgia estuaries may be an adaptive or ecophenolypic response to the overall higher temperatures found in southern parts of its range. As in southern populations of the Atlantic surf clam, Spisula solidissima (Dill wyn, 1 8 17), Georgia estuarine softshell clam populations may mature at a smaller size and never approach the size of the northern “cold water” forms. It would be very interesting to culture transplanted juvenile specimens of M. arenaria from Georgia populations in a suitable New England habitat in order to determine if regional size differences are due more to environmental than to genetic factors. In the cold temperate coastal habitats of New England where softshell clams are harvested commercially for food, shells are reported to commonly reach lengths of up to 7.6- 15.4 cm (Abbott 1986). The largest known shell for Mya arenaria, collected at Barnstable Harbor, Massachusetts, has a length of 1 6.6 cm (Qench 1961). There also remains the possibility that adult clams of “typical” size (8+ cm) occur in Georgia waters, but have not been detected because of the limited and inadequate sampling methods employed thus far. Softshell Clams in the Diet of Georgia Estuarine Fishes Softshell clams occurred in the stomach contents of fishes collected in monthly trawls taken in the North and South Newport River during 1969 as part of a paper mill monitoring study (Dahlberg 1971). There is also an additional record of Mya arenaria from the stomach of an Atlantic stingray collected in June 1972 by trawl in a mesohaline area near the mouth of the Little Ogeeche River, Chatham Co., Georgia (R.W. Heard, unpublished data). As part of a study on the feeding habits of the Atlantic stingray, Dasyatis sabina (Lesueur), collections were made during 1969 in the North and South Newport River systems when softshell clams occurred in benthic samples. It was found that Mya arenaria was an important pari of the spring diet of the stingrays occurring in this area. Between 1967 and 1972, the stomach contents of 321 Atlantic stingrays from a variety of Georgia coastal habitats were examined (R, Heard, unpublished data). Of these rays, 14 (5%) of the 293 rays with recognizable food in their stomachs had been feeding on Mya arenaria (Table 3). Of these 293 rays, 46 were collected from stations 1 0, 1 1, 1 2, and 13 in the North and South Newport River systems where known or suspected populations of softshell clam occurred during 1969, Of the rays examined from these stations on a year-round basis, 13 (28%) had been feeding on softshell clams. Based on examination of 26 rays collected during the spring from these stations, 50% contained from 2 to 17 softshell clams, which in terms of biomass comprised the major part of their diet. The majority of rays found feeding on Af . arenaria occurred at station 1 1 during May and June 1 969, where 1 1 of 1 3 (85%) of the stomachs examined contained clams. During the June collections, many of the softshell clam remains from the ray stomachs appeared to have valve lengths in the 30 mm to 40f mm range , The remaining 20 rays examined from Stations 10-13 were collected during the fall months. They had been feeding predominantly on the commercial while shrimp, Penaeus set if eras (Linnd), and had no softshell clams in their stomach contents. Two small softshell clams were taken from the stomach of a juvenile spotted hake, Urophycis regius (Walbaum), collected during the spring of 1969 from the North Newport River above station 1 1 (Station C of Heard 1 975). These two clams were in poor condition and are no longer available for study (Sikora, unpublished data; Sikora et al. 1972, foomote p.518). In another study (Heard 1975) which deals with the feeding habits of white catfish, Ictalurus catus (Linnd), collected from the North Newport River and its tributaries, no Mya arenaria were observed in the stomach contents of 174 fish examined. Many of these catfrsh were collected at stations C and B (= station 11) during periods when softshell clams were known to be present. Other Cold Temperate-Boreal Spedesin Georgia Estuaries During the spring and winter months, the Baltic macoma, Macoma balthica (Linn^, 1758), and the Atlantic rock crab. Cancer irroratus Stry, 1817 occur in Georgia estuaries. Like Mya arenaria, both are common to cold-temperate and boreal Atlantic regions. Macoma balthica has been reported in Georgia waters (Abbott 1974; Theroux and Wigley 1983; Mayou and Howard 1975; Frey et al. 1 975). Juveniles of the crab Cancer irroratus are not uncommon in the sounds near Sapelo Island (Heard and Heard 1971). Macoma balthica appears to be an important component of winter brackish water benthos of Doboy and Altamaha Sounds, which are part of the greater Altamaha River delta system just south of Sapelo Island (Mayou and Howard 1975; R.W. Heard, unpublished observations). The juveniles of C. irroratus are common winter residents of the lower, high salinity reaches of Georgia sounds. Adult populations south of North Carolina are confined to colder deep-water habitats (Williams 1 984). Juveniles ofC. irroratus have been reported in the diet of hakes collected in Sapelo and St. Catherines Sounds (Sikora etal. 1972). Juvenile hakes, like C. irroratus, occur in Georgia estuaries during the cooler periods of the year, and leave the estuaries during the spring to migrate back into deep offshore waters where the adult populations occur. 93 Rasmussen and Heard TABLE 3 Occurrence of Mya aremuia in 14 stomachs of the Atlantic stingray, Dasyatis sabina, collected from Georgia estuaries during 1967-1970 (North and South Newport River system) and 15)72 (Little Ogeeche River). Collection Date Station Disk Width (cm) Sex No. of Mya in Stomach 5/69 North Newport River 11 24 Female 5 11 24 Female 5 11 25 Female 3 11 26 Female 17 11 32 Female 14 6/69 11 21 Female 2 11 26 Female 2 11 29 Female 5 11 30 Female 10 11 30 Female 12 11 33 Female 16 5/69 South Newport River 13 33 Female 4 13 33 Female 15 6/72 Little Ogeeche River 17 23 Male 12 Conclusions Based on our limited data, we believe that there is a good possibility that year-round, reproducing populations of the softshell clam, Mya arenanOy exist in (jeorgia waters. During the colder months, juvenile populations are often recruited into areas such as intertidal sand banks. During warmer months, however, biotic and abiotic factors such as predation and temperature may make these areas uninhabitable for the clams and thus limit their distribution. The restricted cooler habitats associated with tidal ditches on Sapelo Island and the mesohaline tidal river channels with sand-silt bottom substrata like those associated with the middle reaches of the North and South Newport Rivers may serve as year-round refuges for local breeding populations of Mya arenaria. However, since Theroux and Wigley (1983) have documented that softshell clams occur at depths of over 150 m off New England, it is possible that permanent, offshore populations may be present on the continental shelves of the Carolinas, Georgia, and 94 Extant Populations of Mya arenarja Linn6 from Georgia Estuaries northeastern Florida. Hypothetically, if such a situation exists, then the softshell clams from Georgia estuaries could simply be ephemeral, non-breeding accessory populations representing a seasonal larval recruitment from offshore populations. To our knowledge, however, no populations of Af. arenaria are documented or known from the continental shelf off Georgia or immediately adjacent states. Notwithstanding, softshell clams appear to be a bionomically important component of some Georgia estuarine habitats during winter and spring months. Further studies are needed to establish with certainly whether or not year round breeding populations of Mya arenaria exist in Georgia estuarine waters. Acknowledgments We wish to thank Professor V J, Henry, former Director of the University of Georgia Marine Institute, for his encouragement and support of our research and for arranging the senior author's 197 1-1 972 visit to Sapelo Island. The late Professor Ralph I. Smith, University of California, made many helpful and constructive comments on an early draft of the manuscript. We are especially indebted to Dr. Mary E. Petersen of the Zoological Museum, University of Copenhagen (ZMUC), and Mr. Jerry McLelland, Ms. Dawne Hard, and Dr. Chet Rakocinski of the Gulf Coast Research Laboratory for their many helpful technical and editorial comments on the manuscript. Comments of two anonymous reviewers are gratefully acknowledged. Dr. Thomas R. Waller, Smithsonian Institution, kindly provided some references to recent literature. The late Ms. JanE. Heard was instrumental in the collection of specimens and the compilation of data from the Interstale Paper Company study. We are grateful to Dr. Waller Sikora, Louisiana State University, for his enthusiastic help and support in the collection of specimens and for helping us obtain literature on Georgia records for soft shell clams. Dr. Michael Dalhberg, Mr. Paul Gleun, and Mr. Charles Durant assisted us in the collection, sorting, or documentation of specimens, as well as other aspects of our studies. Geert Brovad and Stine Eller of ZMUC helped with the illustrations. This research was supported in part by a grant from the Georgia Water Quality Control Board, No. UGA-D 2422-122 and by NSF grants supporting the WV Kit Jones, Nos.7 1 0,GB 7060 and GA4497. Literature Cited Abbott, R.T. 1968. Seashells of North America. Golden Pr,NY, 280 p. illus. in color. . 1974. American Seashells, the Marine Mollusca of the Atlantic and Pacific Coasts of North America (2nd ed.). Van Nostrand Reinhold Co., NY, 663 p. 24 pis. . 1986. Seashells of North America. Golden Pi:,NY, 280p. illus. in color, revised edition. Abbott, R.T. andS.P, Dance. 1986. Compendium of Seashells. A Color Guide to More than4200of the World's MaiineShells. Third printing (revised), Madison PubI Assoc, 41 1 p. Bwnard, F.R. 1979. Identification of the living Mya. Venus 38(3):185-2(H. Clench, W.J. 1961. A record size for Mya arenaria. Nautilus 74(3):122. Coomans, H.E. 1962.Thc marinemoUuskfaunaof the Virginian area asabasufordefiningzoobgical provinces. Bcaufortia9:83-104. Dahlbcrg, M.D. 1971. Section I: ^ysical characteristics of the North and South Newport Rivers and adjacent waters. In: M.D. Dahlbcrg (ed.) , An ecological survey of the North and South Newport Rivers and adjacent waters with respect to possible effects of treated kraft mill effluent- Final report to Georgia Water Quality Control Board, UGA No. D2422- 122, April 1971, p 1-35. University of Georgia Marine Institute , Sapelo Island, G A, 280 p. (unpubli shed final report). Dance, S.P. (ed.). 1974. The collector’s encyclopedia of shells. McGraw-Hall Book Co., NY, 288 p. Emerson. W.K.,M,K- Jacobsen, H.S.Fcinberg, and W.E. Old, Jr. 1976. The American Museum of Natural History guide to shells - land, freshwater, and marine, from Nova Scotia to Florida. Alfred A. Knopf, NY, 482 p. Foster, R.W. 1946. The genus Mya in the Western Atlantic. Johnsonia2(20):29-35. Frey, R.W.,M.R- Voorhies,and J.D. Howard 1975. Fossil andrecent skeletalremakis inGoorgiaestuarics. Scnckenbmarit7 :257-296. Gosncr,K.L- 1971. Guide to identification of marineand estuarine invertebrates. Cape Hattcras to the Bay of Fundy, Wiley- Tnterscience, New York, NY, 693 p. Hanks, R.W. 1963. The soft shell clam. US Fish and Wildl Circ 162:1-16. Heard, R.W. 1975. Feeding habits of white catfish from a Georgia estuary. Fla Sci 1975(1 ):20-28. Heard, R.W. and E. J. Heard. 1971. Section HI: Description of the invertd3rale fauna and a discussion of the food habits of two species offish from the study area. Parts 1-3: Invertebrate fauna of theNoiih and South Newport Rivers and adjacent waters. In: M.D, DahlbCTg (ed.), An ecological survey of the North and South Newport Rivers and adjacent waters with respect to possible effects of treated kraft mill effluent Final report to Georgia Water Quality Control Board, UGA No. D2422-122, April 197 1 , p 1 22-246. University of Georgia Marine Institute, Sapelo Island, G A. 280 p, (unpublished final report). HessIand,J. 1946. On the quaternary Mytf period in Europe. Arkiv ZooI37A(8):l-5L Howard, D.J. and R.W. Frey. 1975a. Estuaries of the Georgia coast, U.S.A.: Sedimentology and biology. I. Introduction. Senckenb marit? : 1 -31 . Howard, D.J. and R.W, Frey. 1975b, Estuaries of the Georgia coasl,US A: Sedimentology and biology . n. Regional animal- sediment characteristics of Georgia estuaries, USA: Sedimentology and biology. Senckenb marit7:33-104. 95 Rasmussen and Heard Howard, J.D., R.W. Frey, and H.E. Reineck. 1973. Holocene sediments of iheGeorgiacoastal area.In: R.W . Frey (ed.),The Neogene of the Georgia coast. Dept of Geology, University of Georgia for 8th annual Held trip of the Georgia Geological Society, Athens, GA, p 1-58. Howard, D J., T.V. Mayou, and R.W. Heard. 1977. Biogenic sedimentary structures formed by rays. J Sediment Petrol 47(l):339-346. Kennedy, V.S.andJj\.Mihursky. 1971.Upperleinperaturetolerances of some estuarine bivalves. ChesapeakeSci 12(4): 193-204. LaRocque, A. 1953. Catalogueof therecentMolluscaofCanada. Nat Mus Can Bull 129:1-406. Laurscn,D. 1966. The gcnusAfyain the Arctic Region. Malacologia 3(3):399-418. Matthiessen, G.C. 1960. Observations on the ecology of the soft clam, A/yphw elegansa,ndthebu\lhog,Ranacatebeiana. Proc Helminthol Soc Wash 52(2):180-183. Nikitina, EJ^. 1 Helminths of Decapoda in the Krasnovodsk Bay]. In; BiologisheskieresursyKaspiiskogoMorya.M.S. Gilyarova and G.B. Zevina, Editors. Moscow, USSR: IzdateTstvo Moskovskogo Universiteta 173-185 [in Russian]. Ouspenakaia, A.V. I960. Parasitofaune des crustac6s benthiguesde la mer deBarentz (Expos6 Pr61iminare). Ann Parasitol Hum Comp 35:221-242, Ouspenakaia, A.V, 1963. Parasite fauna of marine benthic Crustacea of the Barents Sea (in Russian). Publications of Academy Sciences of the USSR, Moscow, Leningrad. 128 p. Overstreet, R.M. and H.M. Peny. 1972, A new microphallid trematode from the blue crab in the northern Gulf of Mexico. Trans Am Microsc Soc 91:436-440. Pearsc,A.S. 1945. Bcoiogy of Upogebiaaffinis (S&y). Ecology 26:303-305. Rankin, J.S. 1939. Studies on the trematode family Microphallidae Travassos, 1920. 1. The genus Levinseniella Stiles and Hassall, 190 1 , and description of a new genus, Cornucopula. Trans Am Microsc Soc 58:431-447. Rebecq, J. 1964. Recherches sysUmatiques, biolcgiques et icologiques sur les formea larvaires dequelques Trimatodes de Camargue. Th^c Sciences, Aix-Marseille. 223 p. Rcimcr, L. 1963. Zuc verhreitung dcr adult! und larvenstadien dcr familic Microphallidae Viana, 1924, (Trematoda, Digcnea) in dcr mittlcrcn Ostsce. Z Parasitenk 23:253-273. Schuldt, M. andL.I. Lunaschi. 1985(1987). Apieciacionesaceica del la “castracidn parasitaria”. An Soc Cientifica Argent 215(4«):29-37. Shields, J.D. 1992. Par asites and symbionts of the crab Portunus pelagicus from Moreton B ay, eastern Australia. J Crustacean Biol 12(1 ):94- 100. Stunkard, H.W. 1957, The morphology and life-history of the digcnctic trematode, Microphallus similis (Jagcrskiold, 1900) Baer, 1943. Biol Bull (Woods Hole, MA) 1 12:254-266. Szidat, L. 1964. Hclminthologische Untcrsuchengen an dem Argentinischen Grossmoven Larus marinas dominicanus Lichtenstein und Lauras ridibkundus maculipennis Lichtenstein nebst nenen bcobachtungen ueber die Art- Bildung bei Parasiten. Z Parasitenk 24:351-414, Villot, M.A. 1875. Sur les migrations ct les metamorphoses des Trematodes parasites marins. CR Acad Sci (Paris) 8 1 :475- 477. Yamaguti, S. \91\. Synopsis of degenetic trematodes of vertebrates. Keigaku, Tokyo, Japan. 1800 p. 103 Gulf Research Reports Volume 9 | Issue 2 January 1995 Pseudione overstreeti, New Species (isopoda: Epicaridea: Bopyridae)^ A Parasite of Callichirus islagrande (Decapoda: Anomura: Callianassidae) from the Gulf of Mexico Daniel L. Adkison Texas A&M University Richard W Heard Gulf Coast Research Laboratory, richard.heard^usm.edu DOI: 10.18785/grr.0902.04 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Adkison, D. L. and R. W. Heard. 1995. Pseudione overstreeti, New Species (isopoda: Epicaridea: Bopyridae), A Parasite of Callichirus islagrande (Decapoda: Anomura: Callianassidae) from the Gulf of Mexico. Gulf Research Reports 9 (2): 105-1 10. Retrieved from http://aquila.usm.edu/gcr/vol9/iss2/4 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research ReportSy Vol. 9, No. 2, 105- 1 10, 1995 Manuscript received September 12, 1994; accepted October 17, 1994 PSEUDlONEOVERSTREETI,m\VSPEClES(\SOFOiyA:EFlCARIDEA:BOVYRayAE\ A PARASITE OF CALUCHIRUSISLAGRANDE (DECAPODA: ANOMURA: CALLIANASSIDAE) FROM THE GULF OF MEXICO Daniel L. Adkison^ and Richard W. Heard^ ^ Geochemical ondEnvironmentalResearchGroup, 833 GrahamRoad, TexQsA&M University, College Station. Texas 77845, and 1699 Wesleyan Bowman Road, Macon, Georgia 3121 0, USA ^Invertebrate Zoology Section. Gulf Coast Research Laboratory, P.O. Box 7000, Ocean Springs, Mississippi 39566-7000, USA ABSTRACT Pseudione overstreeti, new species, is a common bopyrid that infests the branchial chamber of the beach ghost shrimp, Callichirus islagrande, occurring along beaches of the Gulf of Mexico jfrom Cape San Bias, Florida to Paraiso, Tabasco, Mexico. Like other members of the genus Pseudiorie that infest callianassid shrimps, the female of P. overstreeti is characterized by biramous terminal appendages which result from the combination of uniramous uropods with the closely associated Lateral plates of pleomrare 6. From the other members of the genus Pseudione occurring on callianassid hosts, P. overstreeti is distinguished by the distinctive development of the coxal and lateral plates on the female and the presence of elongate, posterolateral processes (= urop^s by previous usage) on pleomcrc 6 of the male. Pseudione overstreeti is the second bopyrid from a callianassid host in the northeast Atlantic. The other species, lone thompsoni Richardson, 1904, described from New England waters, infests the branchial chamber of Gilvossius setimanus (DeKay, 1844). Introduction Over the past 15 years, we have collected specimens of the beach ghost shrimp, Callichirus islagrande (Schmitt, 1935), infested with an undescribed branchial bopyrid parasite. Parasitized ghost shrimp were collected using a suction devise or modified “yabbie pump” similar to that described by Manning (1975). Infested C. islagrande occurred in both intertidal and shallow sublidal habitats along sand beaches of the Gulf of Mexico. The description of this new species of bopyrid is the subject of this report. The holotype has been deposited in the National Museum of Natural History (USNM), Washington, D.C. Paratypes are in the collections of the National Museum of Natural History, the Gulf Coast Research Laboratory Museum (GCRL), and the Museum National d'Histoire Naturelle (MNHN-Ep), Paris. Pseudione overstreeti^ new species Figures 1 and 2 Pseudioniinae sp. A.: Rakocinski etaL 1993:102 Material Examined [all infesting Caluchirvs islagrande (ScHMnr, 1935)] HOLOTYPE, 9 (USNM 253087); west end of Horn Island, Mississippi; 9 Oct 1981 ; 1 m water depth; coll. R.W. Heard and DE. Adkison. PARATYPES; Mississippi: Id' (USNM 253088), samecoUecUonas holotype; 2 9 9 (gravid), 2 dd NMHN-Ep. 876 (host present); west end of Horn Island; 05 Jul 1992; swash zone; coll. D.L. Adkison and R.W. Heard. 3 99 (gravid), 29$ on same host, 3dd (USNM 253089); west end of Horn Island; 01 Jun 1993; swash zone to 0.5m; colL D.L. Adkison. 1 9 (gravid), 1 d^ USNM 253090; Ship Island; no date; next to swash; coll. R.W. Heard. Florida; 19 (gravid). Id- (GCRL 1337); Panama City Beach (Bid-A-Wee Beach), Florida; 24 Oct 1990; 0.5m; salinity 33 °/oo; coll. J.Foster. Alabania:29 9 (gravid),2(fd*(USNM253091);GulfShores;Ocil980;0.5 to 1.0 m; coll. R.W. Heard. 29 9 (gravid), 2dd [double infestation]; west end of Dauphin Island; 08 Jul 92; swash zone; coll. D.L. Adkison. Louisiana: 19 (gravid). Id" (USNM 253092); Elmer’.s Island, Jefferson Parish; 21 Jun 1982; coll. R,W. Heard. Other Material Florida: 39 9 (gravid), 3d'd* (1 double infestation); specimens deposited in GCRL Invertebrate Zoology Class Collection [apparently lost]; Cape San Bias, Florida; 28 June 1983, coll. R. W. Heard. 29 (1 gravid), 2d- (USNM 253093); Perdido Key; 16 Jan 1990; swash zone and intertidal coll. R.W. Heard, C. Rakocinski and J.A. McLelland. Alabama: 19 (gravid). Id- (USNM 253094); west end of Dauphin Island; 30 Jun 93; swash zone; coll. 105 Adkison and Heard Figure 1. Pseudione overstreetif new species. Female; A, dorsal view; ventral view, male shown attached to abdomen; C, antennae; D, maxilliped; E» posterior ventral lamina; F, oostegite 1, internal view; pereopod 3; H, pereopod 6; I, pereopod 7; J, pleopod 4; K» pieopod 5; L, left uropod and lateral plate; M> right uropod and lateral plate. Scale 1 = 0.1 mm (C); scale 2 = 5.0 mm (A and B), 1.0 mm (D-F, J-M); scale 3 = 0.5 mm (G-1). 106 New Bopyrid from Gulf Callianassid Figure 2. Pseudione overstreeti, new species. Male: A, dorsal view; antennae; C, pereopod 1 ; D, pereopod 3; pereopod 4; F, pereopod 7. Scale 1 = 1.0 mm (A); scale 2 = 0.2 mm (B); scale 3 = 0.4 mm (C-P). D.L. Adkison. Mississippi: west end of Horn Island; 5 Dec 1980; 0.5 to 1 m; coll. R.W. Heard. 299 (gravid), 2cfcr(USNM 253095); west end of Horn Island; 9 Oct 1981; 0.2 to 1.5 m; coU. R, W. Heard and DX. Adkison. West end of Horn Island; 05 July 1992; coll. D.L. Adkison and R.W. Heard. Louisiana: 19 (gravid), 1 cf (USNM 253096); bay side of Isles Demieres; coll. D.L. Felder; 24 Feb 1991. Texas: 59 (gravid), 5d* (USNM 253097); Mustang Island, south of Port Aransas; 02 Aug 1990; coll. R.D. Felder and J.L. Stanton, Mexico, Tabasco: 29 (gravid), 2cf (one damaged, without pleon) (USNM 253098); Paraiso; 28 Mar 1991; coll. D.L. Felder and J.L. Stanton. Description Female. Total length 10.0 to 19. 1 mm; head width 3.0 to 6.5 mm; pereon greatest width (pereomere 3) 9.3 to 14.4 mm; pleon length excluding lateral plates 2.0 to 6.1 mm. Distortion angle 15"^. Head with dorsal surface nearly flat; frontal lamina narrow, laterally expanded, with margin often crenulate. Eyes absent. Antennule with 3 articles; covered with scales. Anieraia with apparently 4 articles, articulation indistinct; more than twice length of antennule; covered with scales, more apparent than on antenna. Maxiiliped palp often articulated indistinctly, with setae on distal and medial margins; maxiiliped with numerous fine setae on ventral surface of distal segment. Barbula with 1 pair of unarmed lanceolate, lateral projections (“spur” of Adkison and Heard 1978 or “epipods” of Bonnier 1900), with numerous tubercles between lateral projections; tubercles shorter medially, Pereon broadest at pereomere 3. Dorsolateral bosses on pereomeres 1 -4; lateral margin with tubercles exhibiting variable development. Coxal plates free on pereomeres 1- 4, fused with dorsolateral boss area on pereomeres 5-7; lateral and ventral surfaces tuberculate; tubercles most abundant on proximal ventral surface. Tergal area increasing in size to pereomere 4, then decreasing greatly posteriorly; tergal area on pereomeres 1-4 tuberculate posterolaterally; tubercles often present on pereomere 5. Brood pouch closed, Oostegite 1 with curved, medially directed posterolateral point; internal ridge armed with numerous long tubercles, becoming longer laterally; tuberclesand internal ridge covered withscales. Oostegites 2-5 with tubercles on ventral surface in areas not overlapped by other oostegites; tubercles increasing in size proximally , often developed into ridge posterior to respective pereopod; size and area of tubercular coverage increasing on posterior oostegites; oostegite 5 with tubercles over most of ventral surface. Pereopods with basal carina, both increasing in size posteriorly. Pleon short, width decreasing posteriorly. Uniramous lateral plates on pleomeres 1-6, lengths subequal, with tuberculate margins, dorsal surface without or with few tubercles, ventral surface withnumcrous tubercles, tubercles most abundant on anteroproximal region and often 107 Adkison and Heard developed into ridge. Pleopods 5 biramous pairs, with rami similar in length, width decreasing posteriorly; rami with tubercles on both dorsal and ventral surfaces; with lateral margins having row of tubercles altematingly directed dorsalJy and ventrally, with size and number of tubercles decreasing distally; tubercles most apparent on posterior pairs. Pleopodslongcrllianassociatedlaterdlplates. Uiopods uniramous, similar in appearance to associated sixth pair of lateral plates. Uropods and sixth pair of lateral plates superficially resembling biramous uropods (Figure 1 L,M). Variation. Frontal lamina development variable, related to size of specimen, larger specimens usually more developed; tubercular development most variable on on barbula, internal ridge of oostegiie 1, ventral area of oostegites 2-5, jmd to lesser degree on pleopods. Male. Length without posterolateral elongation of pleomere 6 4.7 to 5.9 mm; width across pereomere 4 or 5 1.7 to 2.3 mm; pleon length at midline, excluding posterolateral elongations, 1.6 to 2.0 mm. Headmuchnarrower than pereomere 1, Eyes indistinct, represented by pair of minute pigment spots, often superficially indistinct. Aniennule with 3 segments. Antenna with 5 or 6 segments, more than twice length of antennule. Maxilliped not seen. Pereun compact without dorsal pigmented areas and lacking midventral tubercles; posterior pereomeres laterally distinct, separated from each other for greater part of width. Pereopods decreasing in length posteriorly, most apparent in dactylus and propodus. Pleon with 6 pleomeres, with pleomeres separated for most of width, becoming produced laterally on posterior pereomeres; pleomere 1 relatively straight, laterally blunt; posterior pleomeres more elongate and directed more posteriorly. Pleopods vestigial or absent, represented by low mounds mesal to lateral processes of pleomeres when present, larger on anterior pleomeres. Pleomere 6 with posterolateral margins elongate and asymmetrically developed (superficially resembling uropods); uropods absent; anal cone with tubercle on posterodorsal surface. Variation. Shape and relative elongation of pleomeres variable; posterior processes on pleomere 6 more robust and shorter than illustrated (Figure 2 A) in some specimens (i.e., a male from Tabasco, Mexico), but lateral processes on pleomere 5 of most ^)ecimens tapered elongate proj ections like those illustrated in Figure 2A. Posterior pleomeres missing in several specimens, probably from host derived damage. Pleopoddevelopmentandaimatureofantennaemore pronounced in immature specimens than in adults. Etymology. The species is named in honor of Robin M. Overstreet in recognitiem of his many contributions to the field of marine parasitology. Distribution. Pseudione overstreeti, like its callianassid host, appears to be endemic to the Gulf of Mexico. It is presently known from Cape San Blas,Florida to Tabasco, Mexico. Habitat. In branchial chamber of the beach ghost shrimp, Callichirus islagrande. Infected hosts have been collected in the intertidal zone to a depth of approximately two meters. Remarks. The combination of strongly tuberculate posterior coxal plates and a pair of elongate terminal abdominal appendages formed by the combination of the uniramous uropods and lateral plates of last abdominal somite (sixth pleomere) distinguish the female of P. overstreeti from that of other nominal members of the genus Pseudione. The male, which lacks uropods and recognizable pleopods, differs from the other described species of the genus by the uniquely elongate, posterolateral margins of its sixth abdominal somite (Fig 2A). Worldwide, numerous bopyrids are known to infest members of the Callianassidae; however, in the northwestern Atlantic only one other species, /o/ie thompsoni^chardson^ 1904 , is known. This species was described from Gilvossius setimanus (DcKay, 1844) (=C. atlantica Rathbun, 1926) collected in New England waters. Pseudione overstreeti and /. thompsoni belong to different subfamilies and are immediately distinguished by the developmentof the lateral plates on the pleon of the female. In /. thompsoniy the lateral plates are greatly branched and appear branchial in nature, while on Pseudione overstreetiy the lateral plates are simple tuberculate processes. Discussion Within the Bopyridae, the number and type of appendages or projections on the sixth pleomere of the female have three interpretations: (1) the uropods are biramous (lateral plates absent); (2) the uropods are uniramous with lateral plates present; or (3) the lateral plates are biramous (uropods absent). At least two of these morphological conditions appear to have evolved in female bopyrids. In the original description of Pseudione lon^icauda Shiino, 1937, a callianassid parasite from Japanese waters, Shiino ( 1 937 : 480) described the female as having uropods that are ^‘uniramous on the left..[and] biramouson the right [,] branching at a short distance from the base.” His illustration of the right uropod (p.48 1 , Figure 2B) indicated a triramous structure composed of a biramous uropod and a lateral plate. The fifth pair of lateral plates on female of P. overstreeti appears to be similar to the unbranched right 108 New Bopyrid from Gulf Callianassid uropodofP. as described by Shiino (1937: 480, Figure 1 A), Later, Shiino ( 1958) examined the uropods of twoaddidonaladultfemalesofF. longicauda and considered the uropods on these specimens to be uniramous. In the same study, however, he reported a juvenile female from the same collection as having a large exopod [lateral plate?] and a rudimentary endopod. In P. overstreeti, the dorsal rami are similar in appearance to lateral plate 5, and the ventral rami are similar in appearance to the rami of pleopod 5. The lateral plates on pleomeie 1-5 and the associated pleopodal rami are different in appearance. The pleopodal rami are more elongate than their respective lateral plates. The differences in structure of the pleopods and lalenil plates of pleomeres 1-5 are similar to the differences between the dorsal and ventral rami of pleomere 6. Based on these observations, we consider the appendages on the sixth pleomere to represent a pair of lateral plates and apair of more ventrally located uniramous uropods. The sixth female pleomere of P. overstreeti has two pairs of elongate projections, which we consider to be derived from the combination of a pair of uniramous uropods and a pair of lateral plates. In male bopyrids, "‘uropods** have two forms. The first is derived from the posterolateral elongations of pleomere 6, and the longer the projections, the more likely they will be considered uropods (see Bourdon, 1968 and Markham, 1982). In the second form, the uropods are described as appendages with distinct proximal constrictions or articulations. In the male of the genera Entophilus Richardson, 1903, Gigantione Kossman, 1881, lonella Bonnier, 1900, Parapleurocrypiella Bourdon, 1972, and Progehiophilus Codreanu and Codreanu, 1963 (not P. sinicus Markham, 1982), the terminal appendages are proximally articulated or constricted. We consider these terminal appendages to be true uropods. Analogous structures arising fix)m the posterolateral margins of the sixth abdominal somite lack any vestiges of a proximal constriction as seen in the male of P. overstreeti. These are terminal, lateral processes and not “true** uropods. The previous inexact usage of the term “uropod** for the appendages or processes on the posterior margin of the last pleomere has allowed two different, non-homologous structures to be referred to as the same. This situation causes problems in systematic studies, because within the Bopyridae, the presence of true uropods would be considered a plesiomorphic character and the presence of highly modified lateral processes would be considered an apomorphic character. For bopyrids, we strongly urge that the term “uropods” be reserved for those structures that are distinctly set off from the pleomere by an articulation or the vestige of an articulation. Ecological notes. As in most other hosts having bopyrid inl'estaiiore5,reproductiveactivi|y inC. islagrandeissupptessGd by the presence of P. overstreeti. We examined ov^ 100 specimens of C. islagrande parasitized with mature pairs of P. overstreeti. and all the hosts appeared to be females. These parasitized specimens had greatly reduced ovaries (Figure 3), and no ovigerous ^ecimens were observed. Even when including hosts infested with juvenile or immature female P. overstreeti. only a single recognizable subadult male host was found, and it wasparasitizedbyajuvenilefemale. Inthismale host, the first major chela was reduced and it appeared to be in transition toafemalefoim. From our limited observations, we are unable to determine whether infestations occurred most commonly on primary females or if many of the hosts arc femalemoiphotypesdcrivedfroni themetamori^sisof juvenile primary males infested with P. overstreeti. Wehavedjserveddoubleinfestationsonsevenaloccasioiis, withafemale-malepairofP. ov^rjtr^e/ioccuiring ineach host branchial chamber. In some instances, both females on the same host were gravid, but in all cases the females were of similar size and development. Other symbionts, such as copepods {Clasidium sp.) and pimiotherid crabs (Pinnixa behreae Manning and Felder, 1989 in Alabama, Mississippi, and Louisiana waters) or P. chacei Wass, 1955 (in Mississippi, Alabama, and Florida waters), oftenco-occunedwilhhosts infested withP.ov^rstre^ We also examined several hundred specimens of Callichirus major (Say, 18 18) from populations co-ocairring with those of C. islagrande infested with P. overstreeti. Although copepods and pinnotherid symbionts were present, we found no bopyrids on C. major. Acknowledgments We wish to thank Robin M. Overstreet for his encouragement and help in our studies on bopyrid isopods over the past several years. We are grateful to personnel of Gulf Islands National Seashore, especially Ted Simons, Karl Zimmerman, and Gary Hopkins, forlogistic and field support. Jerry McLelland, ChetRakocinski, Dawne Hard, and Walter Sikora helped with the collection of specimens. We wish to thank the students of the 1992 and 1993 summer invertebrate classes at Gulf Coast Research Laboratory for their help in the collection of other specimens. Darryl Felder graciously made specimens from Louisiana, Texas, and Mexico available to us for study. The illustrations were inked by Connie McCaughn, and the early drafts of the manuscript benefitted from the constructive comments of Darryl Felder, Sara LeCroy, and Jerry McLelland. This research was supported in part through a contract (CA-5 320-9-8002) with the National Park Service. 109 Adkison and Heard Figure 3. A, photograph of unparasittzed male (left) and female (right) of Callichirus is1agrande\ note orange ovavies seen through exoskeleton of the first two abdominal somites of the female. B, Pseudione overstreeti, new species, in right gill chamber of *^emale*’ C. islagrande* Literature Cited Bourdon, R. 1968. Les bopyridae des mcrs europtencs. Mem Mus Nat Hist Nat Scr A Zool 50:77-424. Manning, R.A. 1975. Two methods for collecting decapods in shallow water. Crustaceana 29(3):317-319. Markham, J.C. 1982. Bopyrid isopods parasitic on decapod crustaceans in Hong Kong and southern China. Proceedings of the first international marine biological workshop: The marine Bora and Fauna of Hong Kong and southern China, Hong Kong. B.S. Morton and C.K. Tseng (eds.). Hong Kong, Hong Kong Univ Pr 1:326-391. Rakcocinski, C.F., R.W. Heard, S.E. LeCroy, J.A. McLelland, and T. Simons. 1993. Seaward change and zonation of the sandy -shore macrofauna at Perdido Key, Florida, USA Estuarine Coastal Shelf Sci 36:81- 104. Shiino, S.M. 1958. Note on the bopyrid fauna of Japan. Report of Faculty of Fisheries, Prcfectural Univ Mie, 3:29-74. . 1937. Bopyrids from Tanabe Bay, IV. Mem College of Sci Kyoto Univ Scr B, 12:479-493. no Gulf Research Reports Volume 9 | Issue 2 January 1995 Trophic Structure of Macrobenthic Communities in Northern Gulf of Mexico Estuaries Gary R. Gaston University of Mississippi Steven S. Brown University of Mississippi Ghet R Rakocinski Gulf Coast Research Laboratory Richard W Heard Gulf Coast Research Laboratory , richard.heard(^usm.edu J. Kevin Summers US. Environmental Protection Agency DOI: 10.18785/grr.0902.05 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Gaston, G. R., S. S. Brown, C. R Rakocinski, R. W. Heard and J. Summers. 1995. Trophic Structure of Macrobenthic Communities in Northern Gulf of Mexico Estuaries. Gulf Research Reports 9(2); 111-116. Retrieved from http:// aquila.usm.edu/gcr /vol9/iss2/5 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gu^Rese 260 km^), small estuarine systems (> 2.6 km^ but < 260 km^), and large tidal rivers (> 260 km^ with aspect ratio >20). Sampling and Sample Analyses Loran-C was used to locale sampling stations where water quality parameters were measured and quantitative benthic macroinvertebrate samples were collected (see methods in Heitmuller and Valente 1991; Summers et al. 1992). Three replicate macrobenthic samples were collected with a modified Van Veen grab (413 cm^). Samples were washed on a 500-pm screen, transferred to bottles containing 10% buffered formalin and Rose Bengal as a vital stain, and shipped for laboratory analysis. Ill Gaston et al. Benthic samples were rewashed in the laboratory on a 500-pm screen, sorted to taxonomic groups for later identification and enumeration, and placed in labeled vials containing 70% ethanol. Ten percent of all sorted samples were resorted to ensure consistency and quality of work. When resorting revealed more than 10% error in removal of organisms, the previous ten samples completed by that sorter were reanalyzed. Organisms were identified to the lowest practical taxon and enumerated, and voucher specimens were compiled. Quality checks of identifications and counts were conducted by senior project taxonomists, and greater than 10% error resulted in reanalyses of samples. A complete description of quality assurance procedures used in this program is available in Heitmuller and Valente (1991) and Summers et al. ( 1992). Macrobenthic Trophic Group Assignments Each of the macrobenthic organisms identified during the study period was assigned to a trophic group ba.sed on feeding behavior and food type. Trophic groups used in this study were surface-deposit feeders (SDF), subsurface- deposit feeders (SSDF), suspension and filter feeders (FF), carnivores (CARN), omnivores (OMNI), and others (XXX) (sensw Gaston and Nasci 1988). Trophic group assignments were based on morphological and behavioral characteristics of estuarine macrobenthos supported by peer-reviewed scientific literature, unpublished observations, and personal expertise of the authors. Count data for species that fed by more than one method were evenly divided among the feeding groups assigned to that species (e.g., spioiiid polychaetes feed both on suspension matter and surface detritus; hence FF/SDF). Data Analysis Macrobenthic abundance data from 201 randomly selected base stations were used to estimate relative proportions of each trophic group found in estuaries of the northern Gulf of Mexico (i.e., Louisianian Province). This province-wide analysis was completed using data from randomly selected base stations for 1 991 and 1 992 combined, as well as for each sampling year independently. In addition to year-to-year comparisons, community structure was compared among four regions of the Louisianian Province. Regional comparisons were based on data from 86 stations (16 in Texas, 13 in Louisiana, 44 in Mississippi-Alabama, 13 in Florida) that represented five estuaries in each region, selected a priori. All four regions were sampled each year. We selected only stations that occurred in embayments or lagoons for regional comparisons, which allowed comparisons of similar habitats. Twenty-eight taxa were considered numerical dominants in this study (i.e., mean density > 22 individual s m'^). Densities were mean numbers of individuals (m'^) among all stations sampled. Differences in macrobenthic trophic structure were evaluated using a log-likelihood ratio or G-tesl (alpha =0.05) employing intrinsic hypotheses (Zar 1984). Null hypotheses tested whether trophic ^oup frequency distribution (trophic structure) was independent of sampling year and region. Distributions within six feeding groups were compared between two years and among four regions (i.e., 2x6 and 4x6 contingency tables). These analyses were completed using the relative abundance of each trophic group weighted for (multiplied by) the number of stations represented. The calculated test statistic was compared to the chi-square distribution, using (r-l) (c-1) degrees of freedom (d.f. = 5 for between years, and 15 for among regions). Finally, in addition to comparisons of trophic structure (G -tests), comparisons of mean total macrobenthic density (m'^) among regions were made using Wilcoxon paired T-tesls (alpha = 0.05) based on the ten most abundant taxa in each region. Results Approximately 70,890 macrobenthic organisms (840 taxa; mean density, 2846.4 organisms m*^) from 201 stations (603 samples) were collected. Thesestations werenumerically dominated by Medioniastus californiensis (subsurface- deposit feeding polychacte; mean density, 386 m‘^), Corophium cf, lacustre (surface-deposit feeding amphipod; mean density, 178 m'^), Mulinia lateralis (filter-feeding bivalve; mean density, 129 m ^), juvenile and unidentifiable tubificid oligochaetes (subsurfacc-deposil feeders; mean density, 1 lOm'^), Probythinella louisianae (surface-deposit feeding gastropod; mean density, 109 Streblospio benedicti (surface-deposit/filter-feeding polychaete; mean density, 85 m'^), and Texadina sphinctostoma (surface- deposit feeding gastropod; mean density, 79 m ^) (Table 1). Nearly equal proportions (25 - 30%) of the three categories of detritivores (FF, SDF, and SSDF) accounted for approximately 85% of llie macrobenthic fauna in northern Gulf of Mexico estuaries (Table 2). Carnivores (CARN), especially nemerteans, represented approximately 12% of total macrobenthic abundance, while omnivores (OMNI) and others (XXX) each accounted for less than 4% of total macrobenthic abundance. Results from G-rests indicated that trophic distributions were not different between 1991 and 1992 (G=4.1,critical values 1 l,Q70;donoirejectHj^,despitcapparcnt shifts in the relative abundance of SSDF and FF (Table 2). Significant differences in macrobenthic trophic structure were not found among large estuaries from the four geopolitical regions (G = 9.4, critical value = 24.996; do not reject Hq), despite relatively greater numbers of CARN in Louisiana and Florida, and fewer SDF in Louisiana (Table 3). Greater proportional representation by 112 Macrobenthic Trophic Structure of Estuaries TABLE 1 Numerically dominant macrobenthic taxa collected in Gulf of Mexico estuaries (1991-1992). Data for 201 randomly selected stations (603 samples). Taxa Trophic Group Mean Density (m'^ Mediomastus cal^orniensis SSDP , 386 Corophium cf. lacustre SDF 178 Mulirua lateralis FF 129 unidentiHed Tubiiicidae SSDF 110 Prohyikinella tauisianae SDF 109 Siretdo^io benedicti SDF/FF 85 Texadina sphinctostoma SDF 79 Paraprionospio piimata SDF/FF 58 Spiochaetopterus costarum FF 54 Caecum johnsom OMNI 47 Myriochele oculata SSDF 41 Hohsonia florida SDF 40 unidentified Nemertea CARN 36 Crassinella lunulata FF 35 Nemertea sp. B CARN 35 Rangia cuneata FF 35 Nemertea sp. A CARN 34 Tubificoides heterochaetus SSDF 33 Parandalia sp, A CARN 32 Ampelisca abdiia FF 27 Notomastus laiericeus SSDF 26 Magelona sp, H SDF 26 Acieocina canalicutata CARN 24 Balanus sp. FF 24 Prionospio pygmaea SDF/FF 24 unidentified Maldanidae SSDF 23 Prionospio perkinsi SDF/FF 23 Phoronis muelleri FF 23 Petricola pholadiformis FF 22 TABLE Macrobenthic community trophic structure by year for northern randomly selected stations (603 samples). 2 Gulf of Mexico estuaries. Data collected from 201 Trophic Group Mean number of organisms m'^ (proportions of each group) 1991 & 1992 1991 1992 SDF 833.2 (29.3) 724.8 (29.7) 943.3 (28.9) SSDF 782.5 (27.5) 532.5 (21.9) 1035.0 (31.7) FF 712.7 (25.0) 737.7 (303) 687.9 (21.1) CARN 349.9 (12.3) 278,3 (11.4) 422.8 (13.0) OMNI 63.2 (2.2) 77.4 (3.2) 48.8 (13) OTHER 104.9 (3.7) 86.2 (3.5) 123.8 (3.8) TOTALS 2846.4 (100) 2436.5 (100) 3261.6 (100) 113 Gaston et al. CARN in Louisiana estuaries was primarily due to high abundance of Acteocina canaliculata (Gastropoda), nemerteans, and Gtycinde solitaria (Polychaeta). Stations in large estuaries of Florida also contained a higher proportion of CARN, including Acteocina canaliculata, nemerteans, and the carnivorous polychaetes Lumbrineris sp., Goniadides carolinae, and Polygordius sp. While macrobenthic trophic structure was found to be relatively similar among large estuaries from the four regions, results from Wilcoxon paired T-tests indicated that mean total macrobenthic density differed among regions (P < 0.003). Macrobenthos more densely populated estuaries of Mississippi- Alabama (mean density, 3160.5 m’^) than estuaries of Texas (mean density, 1990.5 m'^), Louisiana (mean density, 1994,8 m'^), or Honda (mean density, 2441 .2 m'^). Discussion Benthic macroinvertebrate communities are important functional components of estuarine ecosystems. Macrobenthic organisms alter physical and chemical conditions at the sediment-water interface, promote the decomposition of organic matter, recycle nutrients for photosynthesis, and transfer energy to other food-web components (e.g., Rhoads 1 974; Boesch et al. 1976; Diaz and Schaffner 1 990; Day et al. 1 989). Our use of functional trophic groups to characterize the role of macrobenthos in estuaries incorporates estimates of macrobenthic community structure, and assesses or infers community function. This approach is essential to understanding estuarine ecosystems, because it provides information about food-resource availability and food-web interactions, and may be useful for assessing differences in ecosystem structure and function over space and time. We hypothesize that changes in proportions of trophic groups among estuaries are reflective of food allocations. For instance, estuarine habitats with an abundance of suspended food might be expected to be dominated by suspension feeders, but only when the food is limiting and/or it is ingested before reaching the bottom (Gaston and Nasci 1988). Once at the sediment surface it may be consumed by SDF, or if it is in abundance and sedimentation rates exceed consumption rates, it may be buried and consumed by SSDF. Certainly the distribution and structure of benthic macroinvcrtcbratc communities in estuaries is governed by many interacting environmental parameters and anthropogenic factors. Species richness and abundance have been shown to vary along a number of environmental gradients including salinity (e.g., Sanders et al. 1965; Boesch 1971; Boesch 1977; Flint and Kalke 1985; Gaston and Nasci 1988), substrate or sediment type (e.g., Boesch 1973; Flint and Kalke 1985; Llanso 1985; Diaz and Schaffner 1990), and dissolved oxygen concentration (Boesch and Rosenberg 1981; Gaston 1985; Rabalals and Harper 1992). Many contaminants partition to sediments, creating a major sink and potential source for organism exposure that affect benthic distributions. For example, Gaston and Young (1992) found that sediment contaminants altered the macrobenthic trophic structure of estuaries in Louisiana. TABLES Macrobenthic community trophic structure by region for northern Gulf of Mexico estuaries (1991-1992). Data collected from 86 stations (258 samples) in selected large estuaries from four geopolitical regions. Mean number of organisms (proportions of each group) Trophic Group TX(16) LA (13) MS-AL(44) FL (13) SDF 408.1 (20.5) 258.9 (13.0) 1103.9 (34.9) 597.9 (24.5) SSDF 584.1 (29.4) 402.3 (20.2) 682.5 (21.6) 446.4 (18.3) FF 646.7 (32.5) 723.3 (36.2) 643.5 (20.3) 430.2 (17.6) CARN 229.5 (11.5) 578.6 (29,0) 457.2 (14.5) 603.5 (24.7) OMNI 56.0 (2.8) 8.1 (0.4) 163.3 (5.2) 31.7 (1.3) OTHER 66.1 (3.3) 23.6 (L2) 110.1 (3.5) 331.5 (13.6) TOTALS 1990.5 (100) 1994.8 (100) 3160.5 (100) 2441.2 (100) 114 Macrobenthic Trophic Structure of Estuaries The numerical dominance by detritivores (85% of macrobenthic fauna) in this study is indicative of the major role of detritus in northern Gulf of Mexico estuaries. Quantities of detritus are provided to estuaries from several sources, most notably vascular plant and planktonic production (reviewed by Day et al. 1989). The fate and trophic significance of organic detritus to estuaries has been discussed indetail el sewhere(e.g., Darnell 1967; Heard 1982; Day et al. 1 989; D’Avanzo and Valiela 1990; Schwinghamer et al. 1991; Kristensen et al. 1992) and will not be reviewed here, except to emphasize the salient points of this study. Understanding densities of macrobenthic organisms supported by the detrital food chain in the study area should facilitate future development of estuarine food webs and energy-flow models, and provide a more accurate assessment of the functional roles of macrobentlios in processing detritus. The detritivores that numerically dominated estuaries of the northern Gulf of Mexico included few deep-burrowing forms that typify some large estuaries of the United States east coast (Diaz and Schaffher 1990). The SSDF were dominated by Mediomastus calif orniensiSy a species of polychaete that inhabits shallow tubes. M. californiensis was abundant throughout llie study area. There also were dense populations of FF species that inhabited the sedmient- water interface, such as bivalves (especially Mulinia lateralis). The SDF included a greater diversity of species than the SSDF or FF. Gastropods Probythinella louisianae and Texadina sphinctostoma and several species of tube- dwelling spionid polychaetes densely populated many estuaries of Louisiana and Texas. There have been few studies of the macrobenthic trophic structure of Gulf of Mexico estuaries. The numerical dominance by detritivores in this study generally is similar to results from Calcasieu Estuary, Louisiana (>90% detritivores; Gaston and Nasci 1988; Gaston et al. 1988), Corpus Christi Bay, Texas (generally >90%; Flint and Kalke 1985, 1986a, 1986b), and low-salinity nearshore waters off Cameron, Louisiana (an offshore extension of the Calcasieu Estuary; Gaston 1985; Gaston et al. 1985; Gaston and Edds 1994). We found higher proportions of CARN in llie present characterization of all northern Gulf of Mexico estuaries than were reported for either Calcasieu Estuary or Corpus Christi Bay, perhaps reflective of the fine sediments in the latter two esmaries. Generally, greater proportions of CARN occur in sandy habitats. The ratio of camivorons macrobenthos (i.e., infaunal predators) may be as high as 0.25 in sand or as low asO. 12 in mud (Ambrose 1984), butmay vary widely depending on the predatory species that dominate each habitat. Furthermore, standing crops of C ARNmay vary as a function of production rates of primary consumers. Thus, even though the ratios of trophic groups may be similar among regions, species that play those roles, and their functional behavior may vary. For instance, several species of nemerteans (CARN) and the polychaete Sigambra tentaculata (CARN) dominated most fine-sediment habitats in Louisiana, goniadid polychaetes such as Glycinde solitaria (CARN) d^inaied sandy mud throughout the study area, and a variety of predatory macrobenthos, especially the annelid Polygordius spp. (CARN), dominated sandy habitats in Florida and Texas. Each of those species plays a particular role as a CARN in the macrobenthic community, almost certainly selects and ingests specific foods, and attains its food in a unique manner. The value of using trophic groups to study macrobenthos is that trophic analyses allow characterization of a habitat by inclusion of ail taxa, and results in establishment of a broad-scale model of macrobenthic resource allocation. However, the inferences that can he drawn from such a study are only as strong as the information on those species that compose each trophic group. Particular functions, population variations, and feeding of species in each region must now be analyzed before details on energy transfer at smaller scales can be interpreted. Such studies will allow researchers to establish the source and fate of energy resources of a given estuary to help interpret and test our functional model. Data of this study demonstrated the general distributions and densities of each trophic group, assessed the unique trophic characteristics of estuarine regions, and gave insight into the numerically dominant species involved. One of tlie major advantages of the probability-based sampling design used for this study was the application of the data to broad-scale characterizations of estuaries in ilie Gulf of Mexico. These characterizations can be used to assess the condition of estuarine resources in the study area (Summers et al. 1992) and provide testable hypotheses concerning many aspects of estuarine function. This study provided a baseline for future examination of specific relationships between macrobenthic trophic structure and environmental or contaminant variables of Gulf of Mexico estuaries (see Engle et al. 1994; Brown et al. Ms.). Acknowi.edgments The authors gratefully acknowledge the help of personnel at the University of Mississippi, especially A. McAllister, R. Woods, T. Randall, and C, Lehner. We also thank S. LeCroy, D. Hard, and J. McLelland at ilie Gulf Coast Research Laboratory (GCRL), and personnel at the Gulf Breeze EPA Laboratory, especially!. Macauley and V. Engle. This project was funded under a Cooperative Agreement between EPA and GCRL (CR8 18218-01) and a subcontract from GCRL to the University of Mississippi. 115 Gaston et al. Literature Cited Ambrose, W.G., Jr. 1984. Role ofpredatory infauna in structuring marine soft-bottom communities. Mar Ecol - Progress Ser 17:109-115, Brown, S.S.,G,R.Gaston,C.F.Rakocinski,R.W, Heard, and J.K. Summers. Trophic structure and contaminants in northern Gulf of Mexico. Manuscript in review. Darnell, R.M. 1961. Trophic spectrum of an estuarine community, based on studies of Lake Pontchatrain, Louisiana. Ecology 42:553-568, , 1967. Organic detritus in relation to the estuarine ecosystem. In: Estuaries. AAAS Publication No. 83:376-382. D’Avanzo, C. and I. Valiela. 1990. Use of detrital foods and assimilation of nitrogen by coastal detritivores. Estuaries 13:20-24. Day, J.W., Jr., C.A.S. Hall, W.M. Kemp, and A. Yanez-Arancibia. 1989. Estuarine ecology. John Wiley and Sons,NY. 558 p. Diaz, R.J. and L.C. Schaffner. 1990. The functional role of estuarine benthos. In: M. Haire and E.C. Krome (eds.), Perspectives on the Chesapeake Bay, 1990. Advances in estuarine sciences. Chesapeake Research Consortium, Gloucester Point, VA, p 25-26, Engle, V.,J.K.Summers,andG.R. Gaston. 1994, Abenthic index for the Gulf of Mexico. Estuaries. In press. Flint, R.W. and R.D.Kalke. 1985. Benthos structure and function in a south Texas estuary. Contrib Mar Sci 28:33-53. . 1986a. Niche characterization of dominant benthic species. Estuarine Coastal Shelf Sci 22:657-674. . 1986b. Biological enhancement of estuarine benthic community structure. Mar Ecol - Progress Ser 31:23-33. Gaston,G.R. 1985. BTects of hypoxia on macrobenthos of the inner shelt off Cameron, Louisiana. Estuar Coast Shelf Sci 20:603-613. Gaston, G.R. and K. A. Edds. 1994, Long-term study of benthic communities on the continental shelf off Cameron , Louisiana; a review of brine effects and hypoxia. Gulf Res Rep 9:57-64. Gaston, G.R., D.L. Lee, and J.C. Nasci. 1988. Estuarine macrobenthos in Calcasieu Lake, Louisiana: community and trophic structure. Estuaries 1 1: 192-200. Gaston, G.R. and J.C. Nasci. 1988. Trophic structure of macrobenthic communities in the Calcasieu Estuary, Louisiana. Estuaries 1 1 :20 1 -2 1 1 . Gaslon,G.R.,P.A. Rutledge, andM.L.Walther. 1985. Theeffects of hypoxia and brine on recolonization by macrobenthos off Cameron, Louisiana (USA). Contrib Mar Sci 28:79-93. Gaston, G.R., J.A. McLelland, and R.W. Heard. 1992. Feeding biology, distribution, and ecology of two species of Gulf of Mexicopolychaetes: f^araonisfidgens and P .pygoenigmatica (Paiaonidae, Annelida). Gulf Res Rep 8:395-399. Gaston, G.R. and J.C. Young. 1992. Effects of contaminants on macrobenthic communities in the Upper Calcasieu Estuary, Louisiana. Bull Environ Contam Toxicol 49:922-928. Heard, R.W. 1982. Observations on the food and food habits of clapperrails {RalluslongirostrisBoddaert) from tidal marshes along the East and Gulf coasts of the United States. Gulf Res Rep 7:125-135, HeitmullerT.andR. Valentc. 1991. Environmental monitoring and assessment program: near coastal Louisianian Province monitoring quality assurance project plan. US Environmental Protection Agency, Gulf Breeze, FL. Krislensen,E.,F.O. Andersen, andT.H.Blackbum. 1992, Effects of benthic macrofauna and temperature on degradation of macroalgol detritus: the fate of organic detritus. Limnol Occanog 37 : 1 404- 1 4 1 9 . Schwinghamer, P., P. E. Kepkay , and A. Foda. 1991. Oxygen flux and community biomass structure associated with benthic photosynthesis and detritus decomposition. J Exp Mar B iol Ecol 147:9-35. Summers. J.K., J.M, Macaulcy, P.T. Heitmuller, V.D, Engle, A.M. Adams, and G.T. Brooks. 1992. Annual statistical summary: EMAP-Estuaries Louisianian Province -1991. US Environmental Protection Agency, Gulf Breeze, FL. EPA/ 6(X)/R-93/001. Zar, J.H. 1984. Biostatistical analysis. Prentice Hall, Inc., Englewood Cliffs, NJ. 718 p. Gulf Research Reports Volume 9 | Issue 2 January 1995 The Distribution and Abundance of the Bay Anchovy, Anc/ioa mitchilli, in a Southeast Texas Marsh Lake System Scott A. Griffith Texas Natural Resource Conservation Commission David L. Bechler Lamar University DOI: 10.18785/grr.0902.06 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Griffith, S. A. and D. L. Bechler. 1995. Ihe Distribution and Abundance of the Bay Anchovy, Anchoa mitchilli, in a Southeast Texas Marsh Lake System. GulfResearch Reports 9 (2): 117-122. Retrieved from http://aquila.usm.edu/gcr /vol9/iss2/6 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. GuIfResearchReports, Vol. 9. No. 2, 1 17-122, 1995 Manuscript received July 22, 1994; accepted August 22, 1994 THE DISTRIBUTION AND ABUNDANCE OF THE BAY ANCHOVY, ANCHOA MITCHILLI, IN A SOUTHEAST TEXAS MARSH LAKE SYSTEM Scott A. GrifTith^ and David L. Bechler^ ^exas Natural Resource Conservation Commission, 4420 Ward Drive, Beaumont, Texas 77705, USA K^enterfor Coastal andMarine Studies, Lamar University, P.O. Box 10037, Beaumont, Texas 77710^0037, USA ABSTRACT A one-year distribution and abundance study on the bay anchovy, Anchoa mitchilli, was conducted in a southeastTexas marsh-lake system from March 1990 through February 1991. Day and night collections were conducted in backwaters, lake shores, and lake centers by seining and trawling. Bay anchovies were the second most abundant fish species collected, and exhibited seasonal, diet and habitat variations in abundance and distribution. Across the study area, seasonal abundance peaks occurred in May and August followingmigration into the marsh and seasonal recruitment. However, within each habitat type, peaks of abundance varied in time of occurrence. W Ithin habitats, sign ificant differences in the mean number of anchovies occurred such that backwaters in the daytime had the greatest number followed by backwaters at night, lake shores in the daytime, and lake shores atnight. Lake center collections showcxl no significant did pattern. The presence of vegetation was associated with reduced anchovy numbers; however, when present, anchovies were significantly more abundant in the daytime than atnight. Introduction Anchoa mitchilli (Valenciennes) is the most abundant species of fidi in the estuarine waters of the northern Gulf of Mexico (Robinette 1983) and comprises the greatest biomass in estuaries along the Atlantic and Gulf coast slates (CHiristmas and Waller 1973; Ferret 1971; Gunter 1963). However, most of what is known about the distribution and abundance of Anchoa mitchilli is from off shore, near shore and estuarine studies, with little attention to marshland habitats. Monaco et al. (1989), Robinette (1983), and Morton (1989) have summarized information on the distribution and abundance of A. mitchilli within large estuaries. Abundance is seasonal, and in the Gulf of Mexico varies from Spring through early winter (Robinette 1983; Ross et al. 1987; Modde and Ross 1983). In East Galveston Bay, peak abundance occurs from April to June (Arnold et al. 1 960) with Galveston Bay showing an abundance of adults and juveniles from May toNovember (Monaco et al. 1 989). In Sabine Lake, adult and juvenile A. mitchilli are found from March through October, with juveniles present into November (Monaco etal. 1989). The abundance and distribution patterns of A. mitchilli result in part from fall and spring migrations to and from deeper waters in bays and on the continental shelf (Christmas and Waller 1973; Hildebrand 1963; Swingle and Bland 1974; VougUtois 1987). Migration of anchovies in and out of the marsh system west of Sabine Lake is well documented (Hartman etal. 1987; Stelly 1980). Their great abundance and small size make anchovies a key element in estuarine food webs (Hildebrand 1963; Christmas and Waller 1973; Darnell 1961; Robinette 1983). Bay anchovies are selective planktivores which link the zooplankton community with larger predatory species (Johnson el al. 1990). From spring through fall, the bay anchovy provides more than half the energy intake of predatory fish in Chesapeake Bay (Baird and Ulanowicz 1989, as cited by Houde and Zastrow 1991). Because of their great abundance and key position in food webs, additional information on the distribution and abundance of A. mitchilli is needed to better understand their significance in estuarine systems. This is especially true for the associated marshes and lakes where little information exists on their distribution and abundance. This study presents information on the distribution and abundance of A. mitchilli in the marsh-lake system lying west of Sabine Lake in Southeast Texas. Specifically, this study examines the temporal and spatial distribution and abundance of the bay anchovy by smdying three habitat types common in marshes. Methods Study Area The study area was located in southern Jefferson County, Texas, west of the south end of Sabine Lake and included Kehh Lake, Sea Rim State Park, and the McFaddin 117 Griffith and Bechler National Wildlife Refuge (Figure 1). The brackish marsh-lake system consists of nine lakes and backwaters connected by meandering streams and man-made cuts. Three habitat types that could be adequately sampled were identified. The habitat tyjies were backwaters, lake shores and lake centers. Backwater habitats were connected to tidal aeeks or lakes by restricted openings or were sheltered from the main body of a lake by a small peninsula of land or an island which lay close to shore. A key point was that backwaters were protected in some way from the wave action which occurred on tlie more open lakes. Lake shores lay along the edges of lakes, and lake centers were at least 100 m or more from shore. Backwater stations were the shallowest ( 5^8.73cm, S.D.=1 5.79), followed by lake shore stations (5?=58.1 cm, S.D.=16.1), and lake center stations (>^124.9cra,S.D.=26.5). Stations exhibited wide variations in substrate composition. Backwater stations had Uie greatest amount of variation in substrate composition, which included mud, silt, and detritus in various combinations. Wave action along lake shore stations prevented silt deposition, resulting in a band of firmly compacted clay 1 to 5 m wide extending out from the shore. Beyond this band, the sediment consisted of a soft silt 6 to 30 cm deep. Starting in May and extending to October, the aquatic plant Ruppia maritima covered 50% or more of stations 4 and 6, and occurred sparsely in stations 3, 5 and 10. By June, R. maritima occupied the entire water column of stations 4 and 6 and covered nearly 100% of both stations as well as the surrounding area. The primary difference between stations was that station 6 was very densely covered while station 4 was less densely covered. Otherwise, the coverage Figure 1. Study area along the Louisiana-Texas Border, Jefferson County, Texas. Incoming tides enter and leave at the east end of Keith Lake and Salt Bayou. Numbers 1-21 represent stations discussed in the text. SRSP stands for Sea Rim State Park which lies between the two sets of vertical and horizontal straight lines representing the park boundary. 118 Anchovy Disttubution and Abundance was nearly uniform within the station. The R. maritima was replaced with filamentous algal mats in October and November. All vegetation died back by December. Protocol From March 1990throughFebruary 199 1,242 collections were made in the study area. Twenty-one stations were estabhshed based on the three habitat types: • back waters (stations 1-7) • lake shores (stations 8-14), and • lake centers (stations 15-21). Stations were numbered east to west following the incoming tides. Lake shores and backwaters were marked with stakes 15 m from the bank. Lake centers were not staked. Stations were sampled monthly with night collections made every other month. Lake shores and backwaters were sampled by pulling a seine from the station markers to the bank. The seine was 6. 1 m long, possessed 6,35 mm knitted mesh, and a 4.6 m opening maintained by lying a rope to the seine poles. Lake center stations were sampled with a 3,66 m trynet (25 mm stretch mesh) fitted with a 6.35 mm bar mesh cod-end liner. The trynet was pulled by boat for three minutes for a distance of approximately 430 m. This distance was originally estimated by timing how long it took to pull the net over 125 m marked off by stakes set out in a marsh lake. All anchovies captured were hardened in 10% fonnalin for 24 hours, washed in water 24 hours, and preserved in 55% isopropyl alcohol. Specimens were returned to the laboratory and enumerated. Type and percent submerged vegetation within stations was visually estimated. Problems with scheduling, equipment failure, and weather caused the postponement or elimination of some collections listed in Griffith (1993). Results During the 12-month collecting period, 49 fish and 14 invertebrate species were collected. Fish represented 67% of all specimens collected and invertebrates 33%. The four dominant taxa were Brevoortia patronus (24,321), A. mitchilU (13,266), Menidia beryllina (5,697), and Micropogon undulatus (5,183). A full breakdown of all species and their yearly totals can be found in Griffith (1993). Bay anchovies comprised 23.3% of the total fish catch with a per catch average of 54.8 (N=242, S.D.=124.8). The temporal distribution and abundance of bay anchovies exhibited two peaks which were seen in all three habitats (Figure 2). Generally abundance increased from March through May, decreased in June, increased in July, and peaked a second time in August. After August, abundance steadily decreased until February, hi lake shore and lake center stations, the first peak abundances of anchovies occurred in April, one month earlier than the in backwaters. The second peaks of abundance occurred in November in lake shores, July in lake centers, and August in backwaters. While anchovies were present in low numbers in lake shore and lake center stations in June, they were nearly absent in backwater stations. The anchovies that were present were mostly juveniles with only a few adults present. Within each habitat type there were no significant differences in the use of stations by bay anchovies (Oneway ANOV A; Backwaters: N=8 1, df=80, F=1 .410, P=0.221; Lake shores: N=83, df=82, F=1.490, P=0.193; Lake Centers: N=78, df=77, F=1.130, P=0355). Differences in the did distribution of anchovies occurred in backwaters and lake shores. In all cases, nighttime collections had lower means than daytime collections, while backwater stations always had the highest means (Table 1). A oneway ANOV A using as treatments day and night collections from backwaters and lake shores (N=164; df=3,160; SD=144,4; F=2.990; P=0.033) foUowed by a Tukey test showed significant differences between day and night collections in botli habitats. The Tukey test revealed that each treatment value calculated (backwaters day- backwaters night = 59.50, backwaters night-lake shores day = 21.10, lake shores day-lake shores night = 4.69) exceeded the critical value (3.68), indicating significant differences in densities within each habitat for day and night collections. The relative abundance of anchovies/habitat/ photoperiod was: backwater stations, daytime (5c=129.6) > backwater stations, night (x=70-l) > shoreline stations, daytime (5?=49.0) > shoreline stations, night (5<=44.3). Lake center collections were not significantly different between day and night collections (N=78,day x=21 .68, night ><=12.00, df=51,t=L570,P=0.12Q). Tlie presence of dense stands of R. maritima and filamentous algae from May-October in backwater stations 4 and 6 allowed two analyses to be made. The first analysis permitted the comparison of vegetated against unvegetated areas. This was done by comparing stations 4 and 6 to stations 1, 3 and 5 for the time period when vegetation was present. Stations 1, 3, and 5 were used as controls because their physicochemical structure was most like stations 4 and 6 (Griffith 1993). The analysis showed that heavily vegetated backwaters possessed significantly fewer anchovies (x=54.0) per collection than unvegetated backwaters(x=161.0)(N=59,DF=53.i=-2.210,P=0.032). 119 Mean Number Mean Number Grifftih and Bechler MAMJJASONDJF MAMJJASONDJF Month Month Figure 2. Mean number of anchovies collected per month in each habitat type and all habitat types combined. Solid bars represent the mean number of anchovies per month. Open bars represent the standard deviations. TABLE 1 Yearly mean catch of A. mitchUU by habitat and time period (Day=L and Night=D), March 15190-Febniary 1991. Anchovy DisTRmunoN and Abundance The second analysis compared vegetated areas at night against vegetated areas in the daytime. Because of skewedness, a Mann Whitney U-test was used to test the rank order of the data (Sokal and Rohlf 1981). The results showed that daytime collections of (N=6, x=99.0) were significantly higher than nighttime collections (N=6, >^.7,P=0.0127). Discussion Reproduction^ habitat structure, diel period, season, and vegetation were all associated with anchovy abundance and distribution. Seasonal distributions and abundances of A, mitchilli in the study area were controlled in part by reproductive periods and seasonal migratioas to and from the marsh. Peak abundances of adults and juveniles in the study area occurred during April-May and July-August, with periods of low abundance occurring in June-July and December-Febmary, depending on the particular habitat. The periods of high and low abundance observed in the marsh lake system are similar to those observed by Herke (1971) and most likely resulted from reproductive periods which occurred two to three months prior to the peak abundances- Manaco ct al. (1989) reported spawning, eggs, and 1 arvae were comm on March through November in nearby Sabine Lake. Larval growth is rapid (Cowan and Houde 1990), and larval and juvenile stages may be completed in 2.5 months with some young-of-the-year maturing by late summer, althou^ most over winter before maturing the following year (Houde and Zastrow 1991). Sielly (1980) found a large net movement of bay anchovies out of the study area in November and December, while a smaller net movement out was detected in May and June accounting for some of the reduced numbers found in January-February and Jimc-July, depending on the habitat type. Along the Gulf and Atlantic coasts, the bay anchovy migrates during winter to deeper waters and out to the inner continental shelf, returning to the estuaries in spring (Christmas and Waller 1973; Hildebrand 1963; Vouglitois 1987; Swingle and Bland 1974). While all the evidence indicates that the bay anchovy is migrating in and out of the study area, at least a small percentage of anchovies remain in the marsh year round. Habitat and diel periodicity were also associated with anchovy distribution and abundance. Anchovies were more abundant in backwaters than lake shores and were more abundant in the daytime than at night in both habitats. Day and night time concentrations of A. mitchilli within lake center stations were not significantly different from each other. This would suggest that any diurnal migratioas^ from backwater and lake shore stations were not solely to lake center stations, but to other areas within the marsh not sampled in this study. Heavily vegetated backwaters possessed signifrcantly fewer anchovies per collection than did unvegetated backwaters, indicating vegetation was a limiting factor. Herke (1971) found a sunilar pattern in his work on semi- irapounded vegetated areas. Cornelius (1984) found A. mitchilli characteristic of unvegetated mud substrate, while others have captured A, mitchilli over, but not in, Thalassia seagrass beds (Scott Holt per. comm.). Castro and Cowen (1991) found no difference in the density of day and night collections of larval A. mitchilli in vegetated areas, suggesting that the presence of vegetation primarily affects juveniles and adults. Anchoa mitchilli is an opportunistic, selective zooplanktivore (Johnson el al. 1990) that may be less successful at foraging in dense vegetation. This hypotliesis is supported by the fact that anchovies collected in vegetated areas have lower body weights than those collected fromunvegetated areas (Herke 1971). However, A, mitchilli was significantly more abundant in vegetated areas in the daytime, suggesting that it may use dense stands of unbroken vegetation as a refuge from predators (Griffith 1993) and then move out to forage al night (Johnson et al. 1990). Literature Cited Arnold, E.L., Jr., R.S. Wheeler, and K.N. Baxter. 1960. Observations on fishes and other biota of East Lagoon, Galvestonlsland. US Fish and Wildl Serv Spec Sci Rep Fish No 34. 4:1-30. Castro, L.R. and R.K. Cowen. 1991. Environmental factors affecting the early life history of bay anchovy, Anchoa mitchilliy in Great South Bay,New York. MarEcol Prog Ser 76:235-247. Christmas, J.Y. and R.S. Waller. 1973. Estuarine vertebrates, Mississippi. In; Cooperative Gulf of Mexico Estuarine Inventory and Study, Mississippi, p 320-406. Gulf Coast Res Lab, Ocean Springs, MS. Cornelius, S. 1984. An ecological survey of Alazan Bay, Texas. Vol. 1. Caesar Kleberg Wildl Res Inst Tech Bull No 5. Kingsville, TX. 1 63 p. Cowan, L.R. and E.D. Houde. 1990. Growth and survival of bay anchovy, Anchoa mitchilli, larvae in mesocosm enclosures. MarEcol Prog Ser 68:47-57. Darnell, RM. 1961.Tioi^icspectrun)ofanestuaiineoommunily, based on studies ofLakcIbntdhaitrain, Louisiana. Ecdogy 42:553-568. Griflitb, S. A. 1993. Habitatu$age,distribution, and abundance di Anchoa mitchilli in a southeast Texas marsh lake system [unpublished masters thesis] Biology Dept, Lamar Univ, Beaumont, TX. 72 p. 121 Griffith and Bechler Gunter, G. 1963. Biological investigations of the St. Lucie Estuary (Florida) in connection with Lake Okeechobee discharges through the St. Lucie Canal. Gulf Res Rep 1 : 1 89- 307. Hartman, R.D., C.F. Bryan, and J.W. Korth. 1987. Community stnicture and dynamics of fishes and crustaceans in a southeast Texas estuary. Subra i tied to U .S. Fish and WUdl Serv Reg Off, Albuquerque, NM . Available firoan LA Coop Fish and W ildl Res Unit, LA Slate Univ, Baton Rouge, LA. 1 16 p. Herkc,W.H. 1971. Useofnatural.andsemi impounded,Louisiana tidal marshes as nurseries for fishes and crustaceans [Ph.D. thesis]. LA State Univ 242 p. Hildebrand, S.F. 1963. Family Engraulidae. In: Y.H. Olsen (ed.), Fishes of Ihe western North Atlantic. Scars Fdn Mar Res. Bingham Oceanogr Lab, Yale Univ 630 p. Houde, E.D. and C.E. Zastrow, 1991. Bay Anchovy. In: Funderburk, S.L., J.A. Mihursky, S.J. Jordan, and D. Riley (eds.), Habitat Requirements for Chesapeake Bay Living Resources, 2nd Edition, p 8.1-8.14. Living Resources Subcommittee, Chesapeake Bay Program. Annapolis, MD. Johnson,W.S.,D.M. Allen, andM.V.Ogbum. 1990. Short-term predation responses of adult bay anchovies , Anchoa mitchilli^ to estuarine zooplankton availability. Mar Ecol Prog Ser 64:55-68. Modde, T. and S.T. Ross. 1983. Trophic relationships of fishes occurring within a surf zone habitat in the northern Gulf of Mexico. Northeast Gulf Sci 6: 109-120. Monaco, M.E., T.E. Czalpa, D.M. Nelson, and M.E. Pattillo. 1989. Distribution and abundance of fishes and invertebrates in Texas estuaries. US Dept Comm . NOAA, Rockville, MD. 107 p. Morton, T. 1989. Species profile: Life histories and environmental requirements of coastal fishes and invertebrates (Mid- Atlantic) - bay anchovy. US Fi.sh and Wildl Serv Biol Rept 82(11.97).! 3 p. Peiret, W.S. 1971. Cooperative Gulf of Mexico inventory and study, Louisiana-Phase IV, Biology. LA Wildl Fish Comm 31-69 p. Robinette, H.R. 1983. Species Profiles: life histories and environmental requirements of coastal fishes and invertebrates (Gulf of Mexico)-bay anchovy and stripped anchovy. US Fish and Wildl Serv, DivBiol Serv, FWS/OBS -82/1 1.14. US Army Corps Engin, TR EL-82-4. 15 p. Ross,S.T.,R.H.McMichcaJ,andD.L.Ruple. 1987. Seasonaland diel variation in the standing crop of fishes and macroinvertebrates from a Gulf of Mexico surf zone. Estuarine Coastal Shelf Sci 25:391^12. Sokal, R.R. and P. J. Rohlf. 1981 . Biometry. W.H. Freeman and Co, NY. 859 p. Stelly , T.D. 1 980, Currents and biota at the Salt Bayou weir and the Keith Lake water exchange pass of Sea Rim State Park [unpublished masters thesis] . Lamar U niv, Beaumont, TX. 126 p. Swingle, H.A. and D.G. Bland. 1974. Asludyofthc fishes of the coaslalwatercourses of Alabama. AiaMarResBuli 10:22-102. Vouglitois.J,J.,K.W.Ablc,R.J.Kurtz,andK.A.Tighe. 1987. Life history and population dynamics of the bay anchovy in New Jersey. Trans Am Fish Soc 116:141-153. 122 Gulf Research Reports Volume 9 | Issue 2 January 1995 A Study of Factors Influencing the Hatch Rate ofPenaeus vannamei Eggs. 1. Effects of Size^ Shape and Volume of the Spawning Tank John T. Ogle Gulf Coast Research Laboratory DOI: 10.18785/grr.0902.07 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Ogle; J. T. 1995. A Study of Factors Influencing the Hatch Rate of Penaeus vannamei Eggs. I. Effects of Size; Shape and Volume of the Spawning Tank. Gulf Research Reports 9 (2); 123-126. Retrieved from http:// aquila.usm.edu/gcr /vol9/iss2/7 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol 9, No. 2, 123-126, 1995 Manuscript received January 4. 1993; accepted October 4, 1993 A STUDY OF FACTORS INFLUENCING THE HATCH RATE OF PENAEUS VANNAMEI EGGS. I. EFFECTS OF SIZE, SHAPE AND VOLUME OF THE SPAWNING TANK John T. Ogle Fisheries Section, Gulf Coast Research Laborato ry, P.O.Box 7000, Ocean Springs, M tssissipp i 39566-7000, USA ABSTRACT The hatch rate of Penaeus vannamei eggs spawned by individual females in square and round tanks and in different volumes of seawater was determined. The mean hatch rates ranged from 17.3% to 64 .9% and were not significantly different for volumes of 50, 100 and 200 L nor for square or round tanks of equal water volumes. Hatch rate was significantly affected by the size of the spawning lank. Introduction Aquaculture accounts for over 25% of the world’s shrimp production (Rosenberry, 1991). The farming of shrimp requires acquisition of seed stock which is reared to marketable size. Seedsiock may be harvested from the wild or produced from broodstock. Broodslock may be sourced from the wild or acquired from maturation facilities. In either case, mated oviparous shrimp are spawned under captive conditions in order to collect the larvae. A variety of systems have been used to spawn marine shrimp. Eggs or nauplii may be collected directly from the tank in which maturation and matings take place (Laubier-Bomchon and Laubier 1979; Brown et al. 1980; Lawrence et al. 1980; Simon 1982; Chenetal. 1991;Ogle 1992). However.many facilities remove the mated females to a separate tank for spawning. Wyban and Sweeney (1991) and Bray and Lawrence (1992) report the stocking of a single mated female into a tank while Lawrence et al. (1980), Kittaka (1981), Aquacop (1983), Yang (1975), Tabb el al. (1975) and Treece (1985) cite that several mated females may be placed in a common tank for spawning. In most cases, spawning and hatching are accomplished in one tank and the nauplii are collected and transferred to another tank for larval rearing. However, Salser (1978) and Bray and Lawrence (1992) recommend that after the shrimp spawn, eggs be removed to a separate tank for hatching. Tanks utilized for spawning and hatching have been as large as 145,800 L (Kinaka, 1981) and as small as 10 L (Mock and Murphy 197 1). Bray and Lawrence ( 1992) suggest 75 L as the minimum tank size with 100 to 150 L circular tanks supplied with lids as the preferred choice for spawning and hatching. Browdy (1992) suggests using atank sizeof 1 50- 500Land Browdy and Samocha( 1985a and 1985b)report that simple flat-bottom tubs are sufficient for the spawning and hatching of eggs. Aquacop (1983) utilizes conical bottom tanks. A comparison of the two tank types, conical and flat-bottomed, with P. setiferus could demonstrate no significant differences in hatch rates (Browdy, in preparation), Lotz and Ogle (1994) report an increasing hatch rate of P. vannamei with an increasing volume of the spawning tanks. However, the spawning tanks varied in size and shape. As these are the only comparative studies on the effect that tank shape and volume have on hatch rates, the present study was undertaken with/*, vannamei. Material and Methods Three different tank types were used for spawning mated P. vannamei females. Rectangular polyethylene tubs, 0.5 1 m X 0.53 m xO.32 m, witha bottom area of 0.27 m^ were utilized as one of the tank types. The other two tank types were both round fiberglass tanks and are referred to as small and large. The small tanks had a diameter of 0.61 m and a depth of 0.45 m with a bottom area of 0.29 m^ while the large tanks had adiametcr of 1 .12 m and adepthof 0.60 m with a bottom area of 0,98 m^ (1 m^). The spawning tanks were filled with a measured volume of seawater. Natural bay water pumped from Davis Bayou in the Mississippi Sound was allowed to stand for several weeks to allow suspended solids to .settle. Artificial seasalt (Marine Environment, San Francisco, CA) was added to increase the ambient salinity of 25 ppi to a salinity of 30 ppt. The water was filtered through a particulate five- micronRS pleated polyester fabric mediacartridge ( Amtek, Howrite, Inc., 3345 Halls Mill Rd., Mobile, AL 36606) and granular activated carbon (Amtek) before use. Sodium EDTA was added at tlie rate of 3 ppm. 123 Ogle Shrimp were matured and mated in large commercial sized maturation tanks (Ogle 1992). Mated females were sourced from the maturation tanks in the evening and placed individually into the spawning tanks. Moderate aeration was provided by a single airstone throughout spawning and hatching. The shrimp were checked for spawning after two to tlnee hours and spent females were returned to the maturation tanks. Tire number of eggs was estimated by subsampling. The water in the spawning tank was stirred and five-10 ml subsamples were collected. Subsamples were taken from the four compass directions and the center of the tank. The samples were transfened to a petri dish and the eggs counted. Data were averaged and the total number of eggs calculated. After 12 -15 hours, the number of nauplii was determined in the same fashion and thehatch rate calculated (% H = #nauplii/# eggs x 100). Only spawns that hatched were analyzed. Data were compared by ANOVA and significant (alpha = 0,05) differences noted. The large (Im^ tanks were used to study the effect of water volume on hatch rate with 50, 100 or 200 L of seawater placed in a tank for each shrimp. Twelve shrimp were individually spawned in citch of the tluee water volumes, for a total of 36 shrimp. Fifty L of seawater were used in aU subsequent studies. The effect of tank shape on hatch rate was determined by comparing spawns in the square tubs, 0.27 m^, and the small fiberglass round tanks. 0.29m2. A total of 14 individual spawns were recorded for the square tanks and 15 individual spawns were recorded for the small round tanks. An additional 14 animals spawning in the small round fiberglass tanks were compared to 14 animals which spawned in the large round fiberglass tanks to determine the effect of tank size on hatch rate. In all studies, eggs were left in the spawning tanks until hatching occurred. After the eggs hatched, the tanks were drained, cleaned and filled with new seawater. Results There were no significant differences for the effect of the water volume in the spawning tanks or the shape of the spawning tanks on hatch rates of P. vannamei eggs (Table 1). The average hatch rates for eggs spawned in 50, 100 and 200 L of water were 45.2, 55.2, and 42.4%, respectively. The average hatch rates for eggs spawned in the square and the small round tanks were 25.4 and 18.2%, respectively. There was a significant effect of tank size on the hatch rates. The hatch rates for eggs spawned into a tank of 0.29 m^ and 1 m2 were 17.3% and 64.9%, respectively. Overall, the minimum spawn size was 39,000 eggs and the maximum spawn size was 230,000 eggs . The minimum egg deasity was 780/L and the maximum was 4,600 eggs/L. This is equivalent to 10,000 to 900,000 eggs/m2. TABLE 1 The effect of tank volume, shape and size on the hatch rate of Penaeus vannamei eggs. Study Treatment Replicates N Mean % Hatch Rate Range % S.E. Significance Volume SOL 12 45.2 3.8 - 89.3 7.10 NS 100 L 12 55.2 15.2 - 100.0 7.21 NS 200 L 12 42.4 1.5 - 90.0 8.54 NS Shape Square 14 25.4 3.8 - 57.8 4,15 NS Round 15 18.2 2.4 - 51.3 5.26 NS Size 0.29 14 17.3 2.0 - 51.3 4.15 SIG 1.00 14 64.9 15.2 - 100.0 6.69 SIG Volume - 1 round fiberglass tank. Shape - square, 0.27 m^ polyethylene tanks with 50 L of water; round, 0.29 m^ fiberglass tanks with 50 L of water. Size - round tanks with 50 L of water. SIG = significant NS = non-significant 124 Factors Influencing Hatch Rate of P, vannamei 1. Discussion While there was a significant effect of the tank size on the hatch rate of P. vannamei eggs, the reason is unclear. The volume in both the large and small tanks was 50 L which created a greater water depth in the smaller tank. The difference in depth does not appear to have an effect on hatching as demonstrated in the experiment on water volumes in this study. This suggests that as long as the femaleisalloweda sufficientarea for unrestricted spawning, the depth of the water beneath the shrimp appears to have no effect on hatch rate. Instead, tank area may play an important role in hatch rate. The average hatch rate reported for P, vannamei of 30% to 47% (Wyban and Sweeney 1 991) is consistent with the rates reported here of 17.3% to 64.9%. It should be pointed out that the hatch rates reported here include three discrete events: spawning, fertilization and hatching. Spawning of P. vannamei occurs as the female slowly swims in circles near the surface of the water. It is possible that restricting the movement of the shrimp to a smaller area may interfere with fertilization of the eggs which would result in a lower hatch rate. It is also possible that the hatch rate may be directly influenced by the bottom area of the tank. As the mechanisms involved in egg fertilization are not known, it is unclear how restricting the swimming activity of the shrimp during spawning would influence fertilization and hatch rates. Heldt (1938) and Hudinaga (1942) have suggested that sperm released from the spennatophore are trapped by the ventral setae of the third and fourth pereopods which come into contact with the eggs as they arc released. We have been unable to detect sperm on the pleopods or pereopods of mated /*. vannamei by microscopic examination. Fertile spawns frequently resul t from matings for which the spennatophore is missing . Fertile spawns have also resulted from femsiles which do not swim but lie perfectly still during spawning. In such incidence, the hatch rate is extremely low (Ogle 1993b). The effect of egg density on hatching is also unknown. Primavera (1980) has recommended that the egg density in spawning tanks for F. monodon not exceed 2J500 to 3,000 eggs per liter. In another study, Primavera et ai (1977) found no effect on the hatching of P. monodon eggs at densi ties of 7000/1. However, they did not report the results in tenns of area (eggs/m^). F. monodon eggs are larger than F. vannamei eggs (Ogle, in preparation) so the densities used here of 780 - 4 ,600 eggs/L should have no effect on the results. This is also supported by the fact that the volume of water didnotsignifreandy affect the hatch rate. Further research could be directed to determined the effect of tank area on fertilization rates and hatch rates. Acknowledgments Appreciation is expressed to Casey Nicholson and Richard King for the daily operation of the maturation systems, Leslie Christmas for data reduction, Kathy Beaugez for aid in manuscript preparation and Dr. Terry McBee for statistical analysis. This project is funded by USDA, eSMR Grant Nos. 2-2537 and 2.2538. Literature Cited Aquacop. 1 983. Constitution of broodstock, maturation, spawning and hatching systems for penacid shrimps in the Centre Oceanologique du Pacifique. In: J.P. MeVey (ed.), CRC Handbook ofMariculturc, Vol. 1 , Crustacean Aquaculture, p 105-121. CRC Press, Boca Raton, FL. Bray, W.A. and A.L. Lawrence. 1992. Reproduction of Penaeus species in captivity. In: A.W. Fast and L.J. Lester (eds.). Marine Shrimp Culture: Principles and Practices, p 105- 121. Elsevier Sci Publ B.V. Amsterdam, The Netherlands. 962 p. Browdy, C. 1992. A review of the reproductive biology of Penaeus species: Perspectives on controlled shrimp maturation systems for high quality nauplii production. In: J. Wyban (ed.), 1992 Proc Spec Sess on Shrimp Farming, p 22-51. World Aquacult Soc, Baton Rouge, LA. 301 p. Browdy, C.L. and T.M. Samocha. 1985a. Maturation and spawning of ablated and nonublated Penaeus semisulcatus dc Haan (1844), J World Maricult Soc 16:236-249. Browdy, C.L. and T.M. Samocha. 1985b. The effect of eye.staUc ablation on spawning, molting and mating of Penaeus semisulcatus de Haan. Aquaculture 49(l):19-29. Brown Jr., A., J. MeVey, B.M. Scott, T.D. Williams, B.S. Middlcditch, and A.L. Lawrence. 1980. The maturation and spawning of Penaeus stylirostris under controlled laboratoiy condidoas. Proc World Maricult Soc 1 1:488-499. Chen, F.,B. Reid, and C.R. Arnold. 1991. Maturing, spawning and egg collecting of the white shrimp Penaeus vannamei Boone in a recirculating system. J World Aquacult Soc 22(3):167-172. Heldt, J.H. 1938. La reproduction chez les Crustaces Decapodes dc la familledes Peneides. Ann InstOceanogr 18(2):31-206. Hudinaga, M. 1942, Reproduction, development and rearing of Penaeus japonicus Bate. Jpn J Zix)! 10(2):305-393. Kittaka, J. 1981 . Large scale production of shrimp for releasing in Japan and in the United Slates and the results of the releasing programme at Panama City .Florida. KuwailB uU Mar Sci 137(2):149-163. 125 Ogle Laubier-Bonichon, A. and L. Laubier. 1979. Controlled reproduction of the shrimp Penaeus japonicus. In: T.V.R. Pillay and Wm. A. Dill (cds.)* Advances in Aquaculture, p 273-276. Papers presented at the FAO Tech Conf on Aquacult. Kyoto, Japan. 26 May-2 June. Fishing News Book Ltd. England. 653 pp. Lawrence, A.L., Y. Akamine, B.S. Middleditch, G.W. Chamberlain, and D.L. Hutchins. 1980. Maturation and reproduction of Penaeus setiferus in captivity. Proc World MaricultSoc 11;48 1-487. Lotz, J. and J.T. Ogle. 1994. Reproductive performance of the white legged shrimp Penaeus vannamei in recirculating seawater systems. J World Maricult Soc 25(3):477'482. Mock, C.R. and M.A. Murphy. 1971. Techniques for raising penaeid shrimp from egg to postlarvae. Proc World Maricult Soc 1.143-156. Ogle, J.T. 1992. Design and operation of the Gulf Coast Research Laboratory penaeid shrimp maturation facility I. Penaeus vannamei. Gulf Coast Res Lab Tech Rep 4, 41 p. . 1993.Tlie stateof our knowledgcconceming reproduction in open thelycum penaeid shrimp with emphasis on Penaeus vannamei. Invertebr Reprod Dev 22(l-3):267-274. Primavera, J.H. 1980. Broodstock of sugpo (Penaeus monodon) and other penaeid prawns. Aquacul Dept, SEAFDEC, Aquacul Ext Manual No. 7. 24 p. Primavera, J.H. , E. Borlongan and R.A, Posadas. 1977. Viability of P. monodon eggs after simulated transport condition. Quarterly Res Rep SEAFDEC 1(4): 11-13. Rosenberry , B . 1990. Shrimp farming in the western hemisphere. In: M.B. New. H. de Saram, and T. Singh (eds.), Technical and Economic Aspects of Shrimp Farming, p 223-251. Proc Aquatech 90 Ck)nf Kuala Lumpur, Malaysia, 1 1-14 June 1990. INFOFISH. 341 p. Salser, B. Larval penaeid shrimp culture techniques utilized by the Environmental Research Laboratory at Puerto Penasco, Sonora, Mexico. Unpublished manuscript. Simon , CM. 1982. Large-scale commercial application of penaeid shrimp maturation technology. J World Maricull Soc 13: 301- 312. Tabb, D.C., W.T. Yang, Y. Hirono, and J. Heinen. 1972. A manual for culture of pink shrimp, Penaeus duorarum from eggs to post-larvae suitable for stocking. Sea Grant Spec Bull 7, Univ Miami, 59 p. Trcecc, G.D. 1985. Larval rearing technology. In: G.W. Chamberlain, M.G. Haby, and R.J. Miget (eds), Texas Shrimp Farming Manual, p 11143-64, Texas Agri, Ext. Serv. pubL invited papers presented at the Texas Shrimp Farming Workshop. 19-20 Nov. 1985, Ctorpus Chxisti, TX. Wyban, J.A. and JJ^. Sweeney, 1991 . Intensive shrimp production technology; The Oceanic Institute shrimp manual. Oceanic Institute, Honolulu, HI, 158 pp. Yang, W.T. 1975. A manual for large-lank culture of penaeid shrimp to the postlarval stages. Sea Grant Tech Bull 31, Univ Miami, 93 p. 126 Gulf Research Reports Volume 9 | Issue 2 January 1995 A Study of Factors Influencing the Hatch Rate ofPenaeus vannamei Eggs. 11. Presence of a Spermatophore John T. Ogle Gulf Coast Research Laboratory DOI: 10.18785/grr.0902.08 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Oglc; J. T. 1995. A Study of Factors Influencing the Hatch Rate of Penaeus vannamei Eggs. II. Presence of a Spermatophore. Gulf Research Reports 9 (2): 127-130. Retrieved from http:// aquila.usm.edu/gcr /vol9/iss2/8 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 9, No. 2. 127-130, 1995 Manuscript received January 4, 1993; accepted September IS, 1994 A STUDY OF FACTORS INFLUENCING THE HATCH RATE OF PENAEUS VANNAMEI EGGS. II. PRESENCE OF A SPERMATOPHORE John T. Ogle Fisheries Section. GtslfCoast Research Laboratory, P.O. Box 7000, OceanSprings, Mississippi 39566-7000. USA ABSTRACT Eighty-thrcc mated Penaeus vannamei females were sourced from a commercial sized maturation tank. The hatch rate was recorded for those shrimp based on the presence of a full spermatophorc, a partial spermatophorc or the loss of the sperm atophore during sourcing and handling. The hatch rates were not significantly different among females for the three spermatophorc conditions. The mean hatch rates were 48.8% for full spermatophores, 43.1% for partial spermatophores and 55.6% for lost spermatophores. The location of the sperm at fertilization and the precise mechanisms of fertilization are still unknown. Introduction Reproduction of open thelycum penaeid (Litopenaeidae) shrimp has been discussedby Chamberlain (1985), Dali el al. (1990), Bray and Lawrence (1992), and Browdy (1992). Ovarian maturation in open thelycum penaeid shrimp occurs daring the iniermolt cycle of the adult female. Mating takes place soon after dusk, four to five hours prior to spawning. Mating is accomplished with the males*s transference of a compound spermatophoie to the female’s thelycum. Apparently, fertilization of theeggs occurs simultaneously with spawning. Early researchers working w ith /* . setiferus were rarely able to coUect females with attached spermatophores (Andrews 191 1; Burkenroad 1934; Hecgaard 1953). Early reports noted that the spermatophores of P, setiferus are easily dislodged (Weymouth et al. 1933; King 1948; Cook and Murphy 1966; Perez-Farfantc 1969, 1975). In fact, Weymouth ct al. (1933) reported that outof 18.487 females examined, spermatophores were found on only 20 of the animals. Cook(1967)obia!nedfertilizedeggsfromfemale P. setiferus bearing no spermatophores. While examining wild female P. setiferus in which no spermatophores were found attached, Bray et al. (1983) detected minute sperm masses 2 mm in diameter. These sperm masses caimot be seen unless the third pair of walking legs are folded back and the thelycum closely examined. Of 103 mated animals examined from the wild, they noted the condition of a “sperm mass only” to be most prevalent (54%), as opposed to partial spennatophores (19%) and full spermatophores (27%). They also noted the sperm mass only condition for P. setiferus held in tanks. There was no significant difference in the number of nauplU or the hatch rate for the three spermatophore conditions. Bueno (1990), working in tanks with another open thelycum Litopenaeid, P. schmitti, noted 79% of the females with full spermatophores and 21% of the mated females with sperm mass only. He found no significant effect when correlating the spermatophoie condition with fertilization and hatch rate. During thecaptiveieproductionof P. vannamei, Toaxme mated females are removed from the large maturation tanks and placed in small spawning tanks. Thefemalesare selected based on the presence of either a full or partial spermatophore. It is also common for the full spermatophores of P. vannamei to become dislodged and lost during handling. In an attempt to document the effect of the spermatophore condition on hatch rates for P. vannamei, the foUowing data are presented. Materials and Methods The shrimp, P. vannamei, were matured and mated in large commercial sized maturation tanks (Ogle 1992). Mated females were sourced for mating and removed from the maturation tanks in the evening. Mated females were placed, one per tank, into Im^ round fiberglass spawning tanks containing 100 L of seawater (Ogle 1995). Prior to sourcing, die spawning tanks were filled with filtered baywater which had been adjusted from 25 ppl to 30 ppl salinity by the addition of an aitifrcial seasalt (Marine Environment, San Francisco, CA). Moderate aeration was provided by a single airsione. The shrimp were checked for spawning after two to three hours and spent females were returned to the maturation tank. The number of eggs was estimated by subsampiing. The water in the spawning tanks was stirred and five 10 ml 127 Ogle subsamples collected from the four compass directions and from the lank center. The samples were transferred to a petri dish and the eggs counted. Data were averaged and the total number of eggs calculated. After 12- 1 5 hours, the number of nauplii was detennined in the same fashion and the hatch rate calculated. A total of 83 mated females was sourced from the maturation tanks. Condition of the spermatophore (full, partial or lost during sourcing) was noted. The effect of the three spermatophore conditions on the hatch rates of all spawns was compared by A VOVA where alpha < 0.05 was significant In some of the individual spawns, none of the eggs hatched. The spawns which produced no nauplii (no hatch) were eliminated from the data set and the data reanalyzed. Results The haichrate of P, vanmmei eggs was notsignificanily influenced by Che loss or partial presence of the spermatophore (Table I). The hatch rate for 49 shrimp retaining a full spermatophore was 3 1 .8 % (S .E. 4.68). The hatch rate for the 16 shrimp retaining only a partial spermatophore was 24.2% (S.E. 7.52). The hatch rate for the 18 shrimp which lost their spcrmatophoies was 18.2% (S£. 5*56). These differences were not significant given the large range in hatchiates (0-100%) and correspondingly large standard error. When the spawns which did not hatch were eliminated from the data set, there was sdll no significant effect of the spermatophore condition on hatch rate. The hatch rate for 32 shrimp with a full spermatophore was 48.8% (SJE. 5.03). The hatch rate for nine shrimp with a partial spermatophore was 43.1% (S.E. 9.33). The hatch rate for ten shrimp with no spermatophore was 32.7% (S£. 7.24). These differences are not significant given the range in hatch rates (3 .8- 1 00%) and correspondingly large standard error. Discussion There is no significant effect of the spermatophore presence at the time of spawning on hatch rate of P. vannamei. This was the conclusion reached by Bray et al. (1983) for P, setiferus. The 13 shrimp with full spennatophoresproduced 53,000 (S.E.M-±24,700)nauplii for a hatch rate of 26,2% (S.E,M. ± 9. 13). The 1 1 animals with wings only produced 109,000 (S.E.M. ± 38,400) nauplii for a hatch rate of 37.2% (S.E.M. ± 8.79). The 52 animals retaining a sperm mass only produced 92,000 (S.E.M.± 13,800)nauplii forahatchiateof 35.2% (S.E.M. ± 3.84). Bueno (1990), working with P. schmittU could find no significant effect on either hatch rate or fertilization rate due to thecondition of the spermatophore. He reported that 408 shrimp with full spcrmatophoies produced an average of 76,558 nauplii (s.d. ± 42,694) per shrimp and 110 shrimp with a partial spermatophore produced an average of 89,903 (s.d. ± 54386) nauplii per shrimp. In addition, he also examined the eggs and calculated a percent TABLE 1 Hatch rate of Penaeus vannamei in relation to spermatophore condition. FuU Partial Lost All spawns % hatch 31.8 24.2 18.2 n 49 16 18 max 100.0 100.0 63.4 min 0.0 0.0 0.0 SE 4.68 7.52 5.56 Spawns that hatched % hatch 48.8 43.1 32,7 n 32 9 10 max 100.0 100.0 63.4 min 3.8 8.0 6.4 SE 5.03 9.33 7.24 128 Factors Influencing Hatch Rate of P. vannamei n. fertilization. Not all fertilized eggs hatch. For the shrimp with full spermatophores, the percent fcrtiluation was 73.46 (s.d. ± 28.03). For the shrimp with a partial spermatophore, the percent fertilization was 71.50 (s.d. ± 30.78). Despite the large .sample size, significant differences could not be determined due to the large variations that exist in fertilization and hatch rates for marine shrimp. Weymouth et al. (1933) reasoned that since the spermatophores are easily dislodged from the females, the eggs must be spawned and fertilized before the spermatophores are lost. Although we now know this is not the case, the actual mechanisms behind egg fertilization in Litopenaeid shrimp is still unclear. Mated females are sourced out of maturation tanks 1-2 hours after mating has taken place. It has been suggested that the spermatophore ruptures (Perez-Farfante 1975; Rente 1 977) and that sperm present on the pereiopods of the female (Heldt 1938; Hudinaga 1942) fertilize the eggs as they brush past. To date, efforts at this laboratory to microscopically verify thepresenceof sperm on die pleopods and pereiopods of spawning P. vannamei have been unsuccessful. The artificial placement of a sperm mass at several locations on mature P. setiferus did not significantly affect the hatch rates (Bray et al. 1983), although the hatch rate of the artificially inseminated shrimp was significantly less than that of naturally mated ^hrirop. It Is not known how sperm are released from the spermatophore. Spermatophores placed in test tubes of seawater at this laboratory did not rupture or release sperm even after five hours exposure, hi some cases when P. vannamei are entirely quiescent during spawning, Uie eggs descend without coming into contact with the spermatophore, pleopods or pereiopods, but they still hatch (Ogle, personal observation). In such cases, a dense mass of eggs are d^osited on the bottom of the tank and the hatch rate is extremely low. King ( 1948) stated that the spermatophore opened and released sperm at the time of spawning, which in turn may be caused by a substance secreted with the expelled eggs. King felt that this substance may chemically or physically break down the spermatophore. In contrast, as verified in this report, fertilizatidn of the eggs is accomplished even though the spermatophore is completely lost prior to spawning. Therefore, it is suggested here that the sperm or sperm mass is released from the spermatophore shortly after mating and several hours before spawning. The location of the spenn at the time of fertilization and the mechanism of egg fertilization are unclear, as is the “need” for the rather complex spermatophore. Female shrimp have been observed manipulating the spermatophore with the pereiopods after mating (Ogle, personal observation). It is not known whether this ruptures the spermatophore or possibly transfers sperm to the oviducts. This repon substantiates for P. vannamei, as for P. setiferus and P. schmitii, that the presence of the spermatophore at spawning does not significantly affect the hatch rate. Acknowledgments I would like to thank Dr. Jeffery Lotz as Principal Investigator, Dr. Terry McBee for statistical analysis, Mr. Casey Nicholson and Mr. Richard King for daily operation of the maturation system and Ms. Kathy Beaugez for aid in preparation of the manuscript. Funding was provided by USDA CSRS Grants No. 2-2537 and 2-2538. Literature Cited Andrews, E.A. 1911. Sperm transfer in certain decapods. Proc US Nat Mus 39(1791):419-434. Bente, P.F. 1975 . Mother shrimping by Marifarms, Inc. Excerpt from Dr. Bente’s keynote address to the Symp onMar Chem Coast Environ Amcr Chem Soc April 1975. Cited in I. A. Hanson and H.L. Goodwin (Editors). 1977. Shrimp and Prawn Farming in the Western Hemisphere. Dowden, Hutchinson and Ross, Inc., Stroudsburg, PA, p 28-29, Bray, W.A., G.W. Chamberlain, and A.L. Lawrence. 1983. Observations on natural and artificial insemination of Penaeas setiferus. In: G.L. Rogers, R. Day, and A Lim (eds.), Proc Inti Warm Water Aquacult Conf, 1983 (Crustaceans), p 392-405 .Brigham Young Univ, HICampus, Laie, HI. Bray, W.A. and A.L. Lawrence, 1992. Reproduction of Penaeus species in captivity. In: A.W. Fast and L.J. Lester (eds.), Marine Shrimp Culture: Principles and Practices, Chapter 5, p 93-170. Elsevier Sci Publ BV. Amsterdam. The Netherlands. 862 p. Browdy, C. 1992. A review of the reproductive biology of Penaeus species: Perspectives on controlled shrimp maturation systems for high quality nauplii production. In: J. Wyban (ed,), 1992 Proc Spec Sess on Shrimp Farming p 22-51. World Aquacult Soc, Baton Rouge, LA. 301 p. Bueno, S.L. 1990. Maturation and spawning of the white shrimp Penaeus schmitti Burkenroad, 1936, under large scale rearing conditions. J World Aquacult Soc 21 (3): 170- 179. 129 Ogle Burkeiuoad, M.D. 1934. The Penaeidae of Louisiana with a discussion of their world relationships. Bull Am Mus Nat Hist 68(2):61-143. Chamberlain, G.W. 1985. Biology and control of shrimp reproductionJn: G.W. Chamberlain, M.G. Haby, and R.J. Migct (eds.), Texas Shrimp Farming Manual, p HU -41. Texas Agricultural Extension Service publication of in vited papers presented at the Texas Shrimp Farming Workshop, 19-20 Nov, 1S185. Corpus Christi, TJC. Cook,H.L. 1967. RepBur Commercial Fish Bio Lab, Galveston, TX Fiscal Year 1966. US Fish A Wildl Scrv Circ 268:6-7. Cook, H.L. and M.A. Murphy. 1966. Rearing penaeid shrimp from eggs to postlarvae. Proc Southeast Assn Game Fish Comm, 19th Ann Conf, p 283-288. Dali, W.B., B.J. Hill, P.C. Rothlisbcrg, and D.J. Sharpies (Editors). 1990. The Biology of the Penaeidae. Adv Mar Biol, Vol. 27, Academic Press. 489 p, Heegaard, P.E. 1953. Observatioiis on spawning and larval history of shrimp, Penaeus settferus (L.). Publ Inst Mar Sci 3(1):75-105, Heldt, J.H. 1938. La reproduction chez les Crustaces Decapodes de la famine des Peneides. Ann Inst Oceanog 18 (2):31-206. Hudinaga, M. 1942. Refuoduction, development and rearing of Penaeus japonicus. Jpn J Zool 10(2); 305 -390. King, J.E. 1948. A study of the reproductive organs of the common marine shrimp, Penaeus setiferus (Liimaeus). Biol Bull94(3):244-262. Perez-Farfante, 1. 1969. Western Atlantic shrimps of the genus Penaeus. US Fish & Wildl Serv Fish Bull 67(3);461-591. . 1975. Spermatophores and thclycaof the American white shrimps, genus Penaeus, subgenus Utopenaeus. Fish Bull 73(3):463-496. Ogle, J.T. 1992. Design and operation ofthe Gulf Coast Research Laboratory Penaeid Shrimp Maturation Facility 1. Penaeus vannamei. Gulf Coast Res Lab Tech Rep 4, 41 p. . 1995. A study of factors influencing the hatch rate of Penaeus vannamei eggs. I. Tank size, shape and volume. Gulf Res Rep 9(2); 123-126. Weymouth, F.W., M.J. Lindner, and W.W. Anderson. 1933. Preliminary reporton the life history of the common shrimp, Penaeus setiferus (Linn.) Bull US Bur Fish 48(1940); 1 -26. 130 Gulf Research Reports Volume 9 | Issue 2 January 1995 Gametogenic Cycle in the Non-Native Atlantic Surf Clam^ Spisula solidissima (Dillwyn^ 1817); Cultured in the Coastal Waters of Georgia Christopher R. Spruck University of Georgia Randal L. Walker University of Georgia Mary L. Sweeney University of Georgia Dorset H. Hurley University of Georgia DOI: 10.18785/grr.0902.09 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation spruck, C. R., R. L. Walker, M. L. Sweeney and D. H. Hurley. 1995. Gametogenic Cycle in the Non-Native Atlantic Surf Clam, Spisula solidissima (Dillwyn, 1817), Cultured in the Coastal Waters of Georgia. Gulf Research Reports 9 (2); 131-137. Retrieved from http://aquila.usm.edu/gcr/vol9/iss2/9 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 9, No. 2. 131-137. 1995 Manuscript received March 3, 1994; accepted March 25, 1994 GAMETOGENIC CYCLE IN THE NON-NATIVE ATLANTIC SURF CLAM, SPISULA SOLIDISSIMA (DILLWYN, 1817), CULTURED IN THE COASTAL WATERS OF GEORGIA Christopher R.Spnick^, Randal L. Walker*, Mary L. Sweeney, and Dorset H. Hurley Shellfish Research Laboratory, Marine Extension Service, University of Georgia. 20 Ocean Science Circle, Savannah, Georgia 3141 1~I01 1 ABSTRACT This study describes the gametogenic cycle of the Atlantic surf clam, Spisula soTidiss 'ima (Dillwyn, 1817), cultured from fall to spring in the coastal waters of Georgia, where it is non-native. Early active stages of gametogenic development began in November, with the majority (83%) of the animals in the early active stage by December. Gonadal 'mdices increased to late active stages by March, with ripe individuals present in April. Spawning commenced in May and continued into June. Sex ratio (0.48 female to 1 .(X) male) was significantly unequal. Results of this study indicate that clams achieved sexual maturity and spawned when cultured in the coastal waters of Georgia. An aquacultural enterprise in Georgia could obtain broodstock for tlic production of the following fall’s seed crop from the prior year’s growout field planted clams before their spring harvest. Introduction The Atlantic surf clam, Spisula solidissima (Dillwyn, 1817), occurs from Nova Scotia to North Carolina (Abbott 1974) and represents the second most valuable clam fishery in the United States. The potential for the development of aquaculture for yearling surf clams in the northeastern US has been investigated (Goldberg 1980, 1989) and attempted commercially (Monte, personal communications). In Georgia, juvenile Atlantic surf clams planted in fall and harvested in spring exhibited some of the fastest growth rates recorded for this species. Clams planted in November (at approximately 10 mm in shell length) achieved a mean size of 50mm in shell lengthby May (Goldberg and Walker 1990; Walker and Heffeman 1990a, b,c,d). The size of this animal is ideal for the raw or steamer clam markets (Kizynowek et al. 1980; Krzynowck and Wiggin 1982). Experimental growout trials in Georgia indicate that the potential for surf clam aquaculture in the southeastern U.S. is excellent (Goldberg and Walker 1990; Walker and Heffeman I990a,b,c,d). Surf clams must be harvested by mid to late spring (April/May), since high summer water temperatures (>28®C) that occur in coastal Georgia wonld cause physiological stress resulting in 100% mortality (Goldberg 1989). The Georgia Department of Natural Resources cunently bans the importation of bivalve seed into the state due to the threat of possible importation of shellfish pathogens along with the seed stock. Therefore, an aquacultural industry would need another method of continuing the propagation and replenishment of slocks for the following year’s crop. This study determines the gametogenic cycle of the non- ♦Corresponding author native Atlantic surf clam when cultured under field conditions in the coastal waters of Georgia and investigates whether or not field-planted animals reach sexual maturity and spawn w ilhin a single year. If this occurs, then a major biological hurdle to the development of this clam as a commercial aquacultural species for the southeastern US fishermen will be overcome. Materials and Methods The first generation of surf clams was spawned within the Shellfish Research Laboratory in the spring of 1991 under guidelines established for the culturing of exotic species by the International Council for the Exploration of the Seas (ICES). The second generation, used in this experiment, was spawned in the laboratory on 5 May 1992. Juveniles were cultured in upwellers and fed Skeletonema sp. and Isochrysis galbana (Tahitian strain) within a temperature controlled room [23 ± 2.0 (SE) ^C] from June until 10 October 1992, On 10 October 1992, clams [19.4 ± 0.12 (SE) mm shell length] were field-planted in 12 mm mesh vinyl coated wire cages (N = 9 cages) at a density of 200 clams per cage (1 m x 1 m x 0.25 m cage). Cages were buried approximately 0.1 m deep at the mean low water mark on a sand flat near the mouth of House Creek, Little Tybec Island, Georgia (Figure 1). In mid- March, cages and animals were transplanted to the spring low water mark. This was done to extend the length of the feeding period in the hopes of enhancing growth rate. Between October 1^2 and June 1993, 30 clams were randomly collected each month from a different cage, measured for shell length (i .e. longest possible measurement, 131 Spruck et al. SKIDAWAY Figure 1. Location of field growout site ofSpisula solidissima at the mouth of House Creek^ Little Tyhee Island, Georgia. SklO (Skidaway Institute of Oceanography) denotes the site where daily temperatures were recorded. anterior-posterior), and a mid-lateral gonadal sample (ca 1 cm^) was dissected from each clam. Gonadal tissue was fixed in Davidson's solution, refrigerated for48 hours, washed with 50% ethanol (Etoh), and held in 70% Etoh until processing. Tissue samples were processed according to procedures outlined in Howard and Smith (1983). Prepared gonadal slides were examined with a Zeiss Axiovert 10 microscope (20X), sexed, and assigned to a developmental stage as described by Ropes (1968) and Kaniietal. (1993). Staging criteria ofO to 5 were employed for Early Active (EA=3) , Late Active (L A=4), Ripe (R;=5), Partially Spawned (PS=2), Spent (S=l), and Inactive (1A=0). Monthly gonadal index (G.I.) values were determined for each sex by averaging the number of specimens ascribed to each category score. Sex ratios were tested against a 1:1 ratio with Chi- Square statistics (Elliott 1977). Statistical analysis of mean gonadal index values wasperformedby Analysisof Variance (ANOVA) and Tukey’s Studentized Range Tests (SRT) using SAS for PC software (SAS Institute 1989). Water temperatures were recorded daily at 0800 from October 1992 to June 1993 at the dock of the Marine Extension Service, Skidaway Island, Georgia, and are presented as biweekly means in Figure 2. This site is approximately 4.5 nautical miles inland from the site where clams were field-planted. Temperature recorders 132 0 N D J FI 1992 1993 Figure 2. Mean ambient water temperatures taken at the Marine Extension Service Dock, Skidaway River from October 1992 to June 1993 and ft'om the field grow out site from April to August 1993. were placed on site from March to June 1993. As shown in Figure 2 , water temperatures at the dock location are generally representative of temperatures at the test site. Results Surf clams grew from a mean shell length of 19.4 mm to 42.6 mm under field conditions from October 1992 to June 1993. Size increased steadily from November until March* remained the same between March ( x = 36.2 mm) and April ( x = 35.9) and increased again from April to June (Figure 3). The decrease in growth rate between March and AprD was probably caused by the stress endured by the animals when cages were moved to the spring low water mark from ihe mean low water mark. Surf clams were inactive (96.6% of total) and early active (3.4% of total) in October 1992 (Figure 4), at amean water temperature of 2 1.3°C (Figure 3). By December ( X temperature = 13.0^C)* 83% of the animals ( x shell length = 25 mm) were in the early active stage. By March ( X temperature = 12.5^C), 70% of the total surf clams 133 Spruck et al. 1992 1993 Figure 3. The increase in shell length of the non-native surf clams, Spisula solidissima, planted at the mean low water mark on an intertidal sandilat at the mouth of House Creek, Little Tybee Island, Georgia. collected were in the late active stage. In early April ( X temperature = 185°C), 55.6% of the total surf clams collected were in the lateactivestageand44,4% were in the ripe stage. Water temperatures increased steadily and in early May reached ameanof 24.9°C when 17.2% of the surf clams were partially spent, 48.3% were late active, and 34.5% were ripe. By June (x temperatures 28.3°C,x shell length = 42.6 mm), 39.3% of the clams were spent and 60.7% were partially spent. Mean gonadal indices for male and female clams are presented inFiguie 5. Statistical analysis showed that there were no significant differences (p = 0.8) between male and female gonadal indices; therefore, mean values presented below are combined means of both sexes. Gonadal indices increased to late active stages by March ( T G.I. =4.0), with ripe individuals being encountered in April (X G.I. = 4.5). Spawning began in May (x G.I. = 4.0) and continued into June ( X G.I. = 1.6) (Figure 4). A total of 259 clams were histologically sectioned, of which 32.8% were undifferentiated, 45.6% were males, and 32.8% were f^ales. The sex ratio was 0.48 female: 1 .00 male and significantly differed from parity (x^ = 22.09; P< 0.0001). Discussion Results of this study indicate that non-native Atlantic surf clams, reared within the coastal waters of Georgia, attained sexual maturity and spawned. InGeorgia, spawning occurs in spring at approximately the time that field planted animals must be harvested. Once ambient water lemperaluresexceed28'^C,totalmortality results. Spawning commenced in May after a 7^C increase in temperature from early April CX = 18.6°C) through May (X = 24.9°Q. This pattern reflected that of a population off the shore of 134 Gametogenic Cycle of Surf Clams in Georgia 1992 1993 Figure 4. The percent frequency of surf clams, Spisula solidissimaf in each developmental stage for animals cultured in cages at House Creek, Little Tybee Island, Georgia. New Jersey as characterized by Ropes (1968). A clam farmer in Georgia could obtain broodstock from field growout plots prior to temperature-induced mortality and the final harvest of the crop. Broodstock could be supplied to a hatchery foreither furUier conditioning in temperature- regulated tanks or animals could be spawned directly after collection. A hatchery operator could produce seed needed for the following fall field planting from yearling animals. One consideration in using yearling surf clams for broodstock is the unequal sex ratio, ^cc there are fewer females produced within the yearling age group. Unequal sex ratio is not an uncommon phenomenon among ju venile bivalves. In this study, yearling surf clams had a sex ratio of 0.48 female to 1 .00 male. Equal sex ratios for surf clams in field populadons have been reported (Ropes 1968; Jones 1981; Sei^ion 1987; Kanti etal. 1993). However, it is not unusual for protandrous bivalves to mature primarily as males within the first breeding season before equal sex ratios occur in older age classes (Joosse and Geraert 1983; Eversole 1989), This has been observed for Mercenaria m^rcgnflria(Eversoleeial. 1980; Dalton and Menzel 1983; Walker and Heffeman V^S\Arciica islandica (RoweU etak 1990), and Panope abrupia (Goodwin 1976; Sloan and Robinson 1984) populations. Since bivalve fecundity is related to size (Eversole 1989), older, larger females will produce more eggs per spawn. Thus, it would be prudent for the hatchery operator to keep yearling females within die hatchery under regulated water temperatures over summer and replant them in field plots the following fall. In this study, the Atlantic surf clam achieved sexual maturity within approximately one year when cultured within the coastal waters of Georgia. Spawning occurred between May and June when animals were at a mean size of 39.2 mm and42.6 nun, respectively . Although the clams were reared in non-native conditions, sexual maturity occurred at a smaller size than previously recorded for Spisula. Belding (1910) in Massachusetts found that sexual maturity could occur in yearling surf clams at a size of 39 mm, but that the majority of clams matured at two years of age and at a size of 67 mm in shell length. Ropes et al. (1969) observed that for an inshore population of clams in Chincoleaque Inlet, Virginia, yearling surf clams attained sexual maturity at a shell length of 45 nun. For a 135 Spruck et al. Llj GO G9 1992 1993 Figure 5. Mean gonadal indices for male and female surf clams, Spisuia soMissima, cultured in cages at House Creek, Little Tybee Island, Georgia. Canadian population, sexual maturity occurred at four years of age and at a size of 80 nun (Sephton and Bryan 1990). In this study, Georgia haicheiy-produced seed (19 mm) obtained a mean size of 42.6 mm by June when field planted in Georgia, whereas, in previous studies, a mean size of 60 mm in shell length had been achieved (Walker and Heffeman 1990a,b). The slower growth observed between March and April is probably related to the initial mean low water planting height and disruption caused by cage movement. Surf clams achieve greater size when planted at the spring low water mark and subiidal areas than at the mean low water mark (Walker and Heffeman 1990b). Thus, greater-sized individuals with a greater potential fecundity can be produced by planting the crop lower in the intertidal zone or in subtidal areas. If a surf clam aquacultural industry develops in Georgia or the southeastern US, the need for the continual introduction of non-native seed from northern US areas or hatcheries would be eliminated. An aquacultural enterprise in Georgia could obtain broodstock for the production of the following fall’ s seed crop from the prior year’ s growout field planted clams before their spring harvest. Thus, once animals are brought into the state under the ICES guidelines for the introduction of exotic species, an industry can be developed from stocks supplied by that single introduction. 136 Gametogenic Cycle of Surf Clams in Georgia Acknowledgments This work was supported by the Georgia Sea Grant Program under grant number NA 84AA-D- 00072. The authors wish to thank Mrs. D. Thompson for typing the manuscript and Ms. S. McIntosh and Ms. A. Boyette for their assistance and expertise with the graphics. Literature Cited Abbott, R.T. 1974. American Seashells, Second Edition. Van Nostrand Reinhold, NY. 663 p. Belding, D.L. 1910. The growth and habits of the sea clam {Macira soUdissima). Rep Comm Fish Game Mass 1909 Publ Doc 25:26-41. Dalton, R, and R.W. Menzel, 1983. Seasonal gonadal development of young laboratory-spawned southern {Mercenarid campechiensis) and northern {Mercemria mercenarta) quahogs and their reciprocal hy brids in northern Florida. J Shellfish Res 2:11-17. Elliott, J.M. 1977. Some methods for the statistical analysis of samples of benthic invertebrates. Freshwater Biol Assoc Sci Pub 25, 160 pp. Eversole, A.G. 1989. GameUjgenesis and spawning in North American clam populations: Implications for culture. In: J. J. Manzi, and M. A. Castagna (cds.), Clam Mariculture in North America. Development in Aquaculture and Fisheries Science, Volume 19, p 75-110. Elsevier, NY. Eversole, A.G., W.K. Michener, and P.J, Eldcridge, 1980. Reproductive cycle of Mercenaria mercenaria in a South Carolina estuary. Proc Natl Shellfish Assoc 70:20-30. Goldberg, R. 1980. Biological and technological studies on the aquaculture ofthe yearling surf clams. Parti: Aquacultural production. Ptoc Natl Shellfish Assoc 70:55-60, . 1989. Biology and culture of the surf clam. In: J.J. Manzi and M. Castagna (cds.). Clam Mariculture in North America. Development in Aquaculture and Fisheries Science, Volume 19, p 263-276, Elsevier, NY. Goldberg. R. and R.L. Walker. 1990. Cage culture of yearling surf clams, Spisula solidissima, in coastal Georgia. J Shellfish Res 9:187-194. Goodwin, C.L. 1976. Observations on the spawning and growth of subtidal geoducks {Panope generosa Gould). Proc Natl Shellfish Assoc 65:49-58. Howard, D.W. and C.S, Smith. 1983. Histological techniques for marine bivalve mollusks. NOAA Technical Memorandum NMFS-FyNEC-25, 97 p. Jones. D.S. 1981. Reproductive cycles ofthe Atlantic surf clam, Spisula solidissima, and the ocean quahog, Arrica islandica off New Jersey. J Shellfish Res 1 :23-32, Joosse, 3. and W.P.M. Geraert. 1983. Endocrinology, In: A.S.M. Saleuddin and K.M. Wilbur (eds.). The Mollusca, Volume 4, Physiology Part I, p 317-406. Academic Press, NY. Kami, A., P.B.Heffernan, and R.L. Walker. 1993. Gametogenic cycle of Spisula solidissima similis (Say, 1822) from St, Catherines Island, Georgia. J Shellfish Res 12:255-261. Kizynowek, J,, R.J, Lcaison, and K. Wiggin. 1980. Biological and technological studies on the aquaculture of yearling surf clams. Part II. Technological studies on utilization. Proc Natl Shellfish Assoc 70:61-64. Krzynowek, J. and K. Wiggin. 1982. Commercial potential of cultured Atlantic surf clams Spisula solidissima (Dillwyn), J Shellfish Res 2:173-175. Monte, D, 1986. Mercenaria Manufacturing Inc., Millsboro, Delaware (personal communication). Ropes, J. W. 1968. Reproductive c^cle of the surf clam , Spisula sotidissirrui, in offshore New Jersey. Biol Bull 135:349- 365. Ropes, J.W., J.L. Chamberlin, and A.S, Merrill. 1969. Surf clam fishery. In: F.E. Firth (ed.). The Encyclopedia of Marine Resources. Van Nostrand, Reinhold Co., NY. 740p. Rowell, T.W.pD.R.Chaisson, and J.T.McLane. 1990. Size and age of sexual maturity and annual gametogenic cycle in the ocean quahog, Arctica islandica (Linnaeus, 1767), from coastal waters in Nova Scotia, Canada. J Shellfish Res 9:195-203. SAS Institute, Inc. 1989. SAS Language and Procedures: Usage. SAS Institute, Inc., Version 6, First Edition. Sephton,T.W. 1987. The reproductive strategy of the Atlantic surf clam, Spisula solidissima (Dillwyn, 1817), in Prince Edward Island, Canada. J Shellfish Res 6:97-102. Sephton, T.W. and C.F. Biyan. 1990. Age and growth determinations for the Atlantic surf clam,5pf.ru/a solidissima (Dillwyn, 1817), in Prince Edward Island, Canada. J Shellfish Res 4:177-186. Sloan, N.A. and S.M.C. Robinson. 1984. Age and gonadal development in the geoduck, Panope abrupta (Conrad), from southern British Columbia, Canada, J Shellfish Res 4:131-137. Walker, R.L. and P.B. Heffernan. 1990a. Plastic mesh covers for field growing of clams, Mercenaria mercenaria (L.), Mya arenaria (L.), and Spisula solidissima (Dillwyn), in the coastal waters of Georgia, Ga J Science 48:88-95. . 1990b- The effects of cage mesh size and tidal level placementon the growth and survival of clams, Mercenaria mercenaria (L.), and Atlantic surf clams, Spisula solidissima (Dillwyn), in the coastal waters of Georgia, NE Gulf Sci 11:29-38. . 1990c- Intertidal growth and survival of northern quahogs, Mercenaria mercenaria (Linnaeus, 1758) and Atlantic surf clams, Spisula solidissima (Dillwyn, 1817), in Georgia, J World Aquaculture Soc 21:307-3 13. . 1990d. Mariculture potential of the Atlantic surf clam, Spisula solidissima (Dillwyn, 1817), in the coastal waters of Georgia. GaJ Sci 48:168-176. . 1995. Sex ratio of northern quahog according to age, size, and habitat from coastal Georgia, Submitted to Trans Amer Fish Soc. 137 Gulf Research Reports Volume 9 | Issue 2 January 1995 A Note on Bycatch Associated with Deepwater Trapping of Chaceon in the Northcentral Gulf of Mexico Harriet Perry Gulf Coast Research Laboratory , Harriet.Perry^usm.edu Richard Waller Gulf Coast Research Laboratory Christine Trigg Gulf Coast Research Laboratory James McBee Gulf Coast Research Laboratory Robert Erdman Florida Institute of Oceanography et al DOI: 10.18785/grr.0902.10 Follow this and additional works at; http://aquila.usm.edu/gcr Part of the Marine Biology Commons Recommended Citation Perry, H., R. Waller, C. Trigg, J. McBee, R. Erdman and N. Blake. 1995. A Note on Bycatch Associated with Deepwater Trapping of Chaceon in the Northcentral Gulf ofMexico. Gulf Research Reports 9 (2): 139-142. Retrieved from http:// aquila.usm.edu/gcr/vol9/iss2/10 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gu^ResearchReportsyo\.9MoX 139-142. 1995 Manuscript accepted November 14, 1994 A NOTE ON BYCATCH ASSOCIATED WITH DEEPWATER TRAPPING OF CHACEON IN THE NORTHCENTRAL GULF OF MEXICO Harriet Perry’ , Richard Walter’ , Christine Trigg' , James McBee' , Robert Erdman^ and Norman Blake^ 'GulfCoastResearchLaboratory.P. O.Box7000, Ocean Springs, Mississippi 39566-7000, USA ^Florida Institute of Oceanography, 8301st Street S., St. Petersburg, Florida 33701 , USA ^University of South Florida. 830 1st Street S., St. Petersburg. Florida 33701, USA ABSTRACT Bycatch associated with deepwater trapping of Chaceon is reported for outer shelf and slope waters of the northcentral Gulf of Mexico. Bycatch was dominated by the isopod, Bathynomus giganteus. Other crustacean megafauna consisted of the majid crab, Rochinia crassa. and the portunid crabs, Benthochascon schmitti and Bathynectes longispina. Finfish bycatch included hagfish, Eptatretus springeri, deepwater shark, Centrophorus uyato and hake, Urophycis cirrata. Materials and Methods Cruises to establish geographic and bathymetric disuibulioti of Chaceon were made in May and August, 1989. Sampling design and protocol are detailed in Waller et al. (this volume). Five areas were sampled; one was located east of the Mississippi River and four were west of the River extending to the Louisiana/Texas border (Table 1). Results and Discussion Four crustacean and five finfish species were collected in association with Chaceon trap sets. Occurrence of bycatch by area and depth is listed in Table 2. Distribution of bycatch species is discussed in relation to published accounts of occurrence in the Gulf of Mexico (Gulf of Mexico) and from cruise records of the RA^ Oregon and RA^ Silver Bay (Springer and BuUis 1956; Bullis and Thompson 1965). Crustacean Bycatch Bycatch was dominated by the isopod, Bathynomus giganteus. Highest catches were made in Areas 8 and 9, west of the Mississippi River. Isopods occurred over all depths sampled, but were generally more abundant at depths of 677 and 860 m . They were collected in temperatures ranging from 5.2 to 1 2.0^C. Bullis and Thompson ( 1 965) found this species widely distributed on mud substrates in the northcentral and eastern Gulf of Mexico at depths from 384 and 549 m over a temperature range of 9,2 to 10.8®C. Brachyuran crabs trapped in conjunction with Chaceon were outer continental shclf^pper slope species whose distribution has been well delineated in the Gulf of Mexico. Their occurrence, as observed in the present study, is consistent with reported data on their geographic and bathymetric ranges. The majid crab, Rochinia crassa, was taken in samples east and west of the Mississippi River. Highest catch occurred al 3 1 1 m in Area 8. Pequegnat ( 1 970) found this crab at depths from 384 to 732 m and noted that this crab was distributed in all quadrants of the Gulf of Mexico with the exception of the southwest quadrant. Springer and Bullis (1956) reported this species from the northern Gulf of Mexico at stations between 87^25' N latitude and 9 1® 1 T W longitude at depths from 357 to 622 m. Crabs in their survey were taken over mud bottoms at temperatures between 10.0 and 10.6X. Soto (1985) listed/?. crassa as a characteristic slope species whose distribution was generally limited by the 1 0°C isotherm. Specimens in the present study were taken al temperatures between 8.4 and 12.7°C. The portunid crabs, Bathynectes longispina and Benthochascon schmittL occurred infrequently and in small numbers. Both species were taken only at 311 m. Benthochascon schmitti is widely distributed in the Gulf of Mexico. Pequegnat (1970) listed B. schmitti as indigenous to the Gulf of Mexico and noted that it occurred within a narrow range of depth, 201 to 511 m. Springer and Bullis ( 1 956) reported depth distribution from 38 to 472 m; however, the reported occurrence at 38 m is questionable. Soto (1 985) grouped this crab with slope species usually distributed below the lO^'C isotherm. Bottom temperatures associated with the capture of B. schmitti in the northern Gulf of Mexico range from 8.6 to 12.2°C (Springer and Bullis 1956, present study). Powers (1977) reported this species predominant on mud substrates, and Soto (1985) noted occurrence over mud/ shell rubble bottoms. 139 Perry et al. TABLE 1 Station locations by area, depth, latitude and longitude. Area Depth (m) Latitude (°N) Longitude (“W) 1 494 88“ 23.00 29“ 03.73 1 677 88“ 24.64 29“ 00.59 1 860 88“ 19.27 28“ 59.67 1 1043 88“ 19.23 28“ 56.02 1 1830 88“ 08.59 28“ 44.08 6 311 90“ 00.01 28“ 06.50 6 494 89“ 56.83 27“ 58.50 6 677 89“ 55.88 27“ 56.25 6 860 89“ 54.74 27° 53.86 6 1043 89“51.39 27“47.95 7 311 91“22.71 27“ 50.59 7 494 91“ 18.38 27° 47.82 7 677 91“21.18 27“ 44.71 7 860 91“23.84 27“ 43.20 7 1043 9r25.80 27“ 36.56 8 311 92“ 04.52 27“ 47.78 8 494 92“ 11.89 27“ 39.98 8 677 92“ 12.39 27“ 37.65 8 860 92“ 13.99 27“ 35.44 8 1043 92“ 08.77 27“ 33.39 9 311 93“02.21 27“ 39, 15 9 494 93“ 07.77 27“ 33,29 9 677 93“ 03.00 27“ 32.88 9 860 93“ 00. 11 27° 29. 16 9 1043 93“08.12 27“ 22.58 Bathynectes longispina occurred in samples west of the Mississippi River in Areas 7 and 9 in water temperatures of 12.7 and 1 1.4°C. respectively. Springer and Bullis (1956) found B, longispina (listed as B. superba) in the eastern Gulf of Mexico from 20 1 to 476 mat temperatures ranging from 8.9 and 1 3.9®C, Soto (1985) reported catches from 174 to 403 m in the Rorida Straits. This species has been associated with a variety of bottom types, including mud/shell, sand/coral, clay/mud and raud/shcll rabble (Springer and Bullis 1956; Soto 1985). Finfish were collected in small numbers at all areas sampled (Table 2). The hagfish, Eptatretus springeri^ was the most numerous species taken, Hagfish were captured in all areas wi th the exception of Area 9. Eighty-eight specimens were collected over depths from 31 1 to 1043m. Temperatures at the time of collection ranged from 5.3 to 12.0 Highest catches were made at 860 m in Area.s 1 and 7 in August, with 1 5 and 1 8 speci mens collected, respectively. Neither Springer and Bullis (1 956) nor Bullis and Thompson (1 965) reported this species from the western Gulf of Mexico. However, records of occurrence in the western Gulf of Mexico exist, with 10 specimens deposited in the Texas Cooperative Wildlife Collection (TCWC), Texas A&M University (John McEachran, personal communication). Specimens deposited in the TCWC were taken at depths ranging 457 to 78 1 m. Our data extend both the upper and lower depth limits for this species in the Gulf of Mexico. Other species taken included the shark, Centrophorus uyato; the Gulf hake, Urophycis dr rata; muraenid eels; and an ogcocephalid. Springer and Bullis (1956) reported both 140 TABLE 2 Bycatch associated with Chaceon trapping in the northcentral Gulf of Mexico. Area Depth Batliynectes longispina Benthochascon schmUti Rochinia crassa Bathynomus gigarueus EptcUretus springeri Centrophorus uyaio Muraenidae Urophycis cirrata Ogocephalidae 1 494 6 33 4 1 677 3 1 4 860 Auk 3 15 1043 3 1830 6 311* 494 78 7 677 36 7 860 May 68 860 Aug* 1043 2 7 7 311 2 2 6 2 494 5 2 677 76 5 860 May 64 1 860 Aug 32 18 1043 39 4 311 43 16 6 1 1 494 60 677 48 4 860 May 131 2 860 Aug 42 2 1 1043 45 1 311 1 2 12 494 3 22 2 677 109 1 49 860 Aug 42 1043 57 Line Lost Bycatch Asscx:iated avtih Trapping of Chaceon Perry et al. C. uyato and U. cirrata (listed as Phycis cirratus) from the Gulf of Mexico. The two specimens of C. uyato collected in this study were taken in the western Gulf of Mexico at depths of 3 1 1 and 860 m, respectively. Gulf hake, V, cirrata^ were collected in each area in dqjths ranging from 311 m to 677 m. Springer and Bullis (1956) found this species in the western Gulf of Mexico at depths ranging from 99 to 192 m with the deepest depth recorded at 402 m in the eastern Gulf of Mexico. LjTERATuitE Cited BuUis, H.R.. Jr. and J.R. Thompson. 1965. Collections by the exploratory fishing vessels Oregon, Silver Bay, Combat, and Pelican made during 1956-1960 in the southwestern North Atlantic. US Fish Wildl Ser Spec Sci Rep Fish 510:1-130. Pequegnat.W.E. 1970. Deep-water brachjoiran crabs. In:W.E. Pequegnat and F.A, Chace (eds,). Contributions on the Biology of the Gulf of Mexico, p 171-204. Texas A&M University, Oceanographic Studies, Vol 1 . Powers, L.W. 1977. A catalogue and bibliography to the crabs (Brachyura)of the Gulf of Mexico. ContMarSciSuppl Vol 20:1-190. Soto,L.A. 1985. Distributionalpattems of deep-water brachyuran crabs in the Straits of Flcffida. J Crustacean Biol 5(3):480-499. Springer, S . and H.R. B ullis , Jr. 1956. Collections by the Oregon in theGulf of Mexico. US Fish Wildl Ser Spec Sci Rept Fish 196:1-134. 142 Gulf Research Reports Volume 9 | Issue 2 January 1995 A Pugheaded Cobia (Rachycentron canadum) from the Northcentral Gulf of Mexico James S. Franks Gulf Coast Research Laboratory, jim.franks(^usm.edu DOI: 10.18785/grr.0902.11 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Franks,}. S. 1995. A Pugheaded Cobia (Rachycentron canadum) from the Northcentral Gulf of Mexico. Gulf Research Reports 9 (2): 143-145. Retrieved from http://aquila.usm.edu/gcr/vol9/iss2/ 1 1 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research RqwrtSfVol. 9,No, 2, 143-145, 1995 1994;aoceptedOctober31, 1994 A PUGHEADED COBIA (RACHYCENTRON CANADUM) FROM THE NORTHCENTR AL GULF OF MEXICO James S. Franks Gulf Coast Research Laboratory, P.O. Box 7000, Ocean Springs, Mississippi 39566-7000, USA ABSTRACT Apugheaded cobia {Rachycentron canadum) cj^tured in the northccntral Gulf of Mexico represents the first record of pugheadedness in cobia. The specimen, a 4-year-old gravid female, exhibited considerable distortion of the premaxillary and maxillary bones, with the length of the snout 4d% shorter than that of a normal cobia of the same length. The anomaly had no apparent effect on feeding, since the stomach contained a substantial amount of food, and the fish was the same length expected of a normal 4-ycar-old cobia. Introduction Pugheadedness has been well documented in many species ofmarine and fresh water fishes (Dawson 1964, 1966, 1971; Dawson and Heal 1976; Burgess and Schwartz 1975). Genetic abnormalities, embryonic development disorders and aberrations induced by enviionmental variables are probable causes of this type of anatomical anomaly (Gudger 1928, 1930, Mansueti 1 960; Schwartz 1 965; Rose and Harris 1968; Hickey 1972; Sindermann 1977; Shariff et al. 1986). Mechanical injury is generally discounted as a primary factor. Pugheadedness has not been previously reported in cobia {Rachycentron canadum). Materials and Methods A pugheaded/?, canadumwas captured on 4 May 1991 by hook and line in the northcentral Gulf of Meidco east of the Chandeleur Islands at 88® 45 ’N, 30“ 00’ W in 8 meters of water. Fork length (FL), total weight (TW) and sex were recorded for the specimen. Head measurements of the pugheaded specimen and a normal cobia were taken for purposes of comparison and in accordance with the definitions of Hubbs and Lagler (1964). Stomach contents were removed and examined The stage of gonad maturation was determined by gross examinatiem. Otoliths (sagittae) were excised from the specimen, cleaned, embedded in Spurt medium and sectioned transversely through the primordium using a Beuhler Isomet low-speed saw. Otolith sections (0.7-mm-thick) were examined under a dissecting microscope using reflected light, and the annuli were counted. Results The specimen was an adult female, measuring 1 1 10 mm FL and weighing 15.8 kg TW. The fish had a blunt forehead and an abnormally short upper jaw (Figure 1). A sizable groove extended vertically in the exposed anterior portion of the snout. The exposed tongue and lower oral cavity were partially pigmented. There was considerable distortion of the premaxilla and maxilla, and the snout was tucked downward and slightly inward, affecting the vertical opening of the mouth (Figure 2). The lower jaw was unaltered but did exhibit substantial abrasion around the outer edge of the lip. No exopthalmia was noted. Other aspects of external anatomy appeared to be normal. The head of a normal cobia is shown in Figure 3, Head measurements of the pugheaded specimen and a non-pugheaded one of the same length and sex (collected by the author) are presented in Table 1. The length of the snout was 46% shorter than that of a normal cobia of the same size. A distance of 44 mm separated the anterior tip of the anomalous snout from the anterior tip of the lower jaw. The frontal bones were slightly elevated resulting in a larger interorbital width and a greater head depth than expected in normal specimens. The head diown in Figure 3 is not the head of the fish described in Table 1 . The stomach contained a 89 mm (total length) croaker (Micropogonias undulatus) and a large amount of well- digested fish remains. Otolith analysis revealed a recently completed fourth annulus. The anomalous specimen’s lengdi was comparable with the mean length (1139 mm FL) reported for normal female cobia with otoliths showing a recently completed fourth annulus (Franks and McBee 1992). The back- 143 Franks calculated FL al annuli I (402 mm), H (768 mm) and 111(955 mm) was also comparable with mean back-calculated FL reported for female cobia at ages I (493 mm), II (797 mm) and lH (991 mm) (Franks and McBee 1992). The specimen was gravid with normally developed ovaries. Discussion The effects of pugheadedness on the individual depend upon the severity of the anomaly (Hickey 1972), Bortone (1972) postulated that such a condition would typically lead to a lack of competitive ability, but that a moderately pugheaded fish could possibly compete on at least an equal level in regard to feeding raechanisuL In spite of the deformity, the anomalous specimen's feeding efficiency apparently had not been significantly limited. The fish was quite robust. The specimen’s length at capture and estimated length at earlier ages indicated that tlie aberration had not altered growth relative to normal cobia, ages I-IV. Peak spawning for cobia in the northern Gulf of Mexico occurs during April - May (Lotz et al. 1992). The specimen’s ovaries were comparable in appearance to gonads from reproductively active female cobia of similar size collected during May. The head of the specimen is in the Gulf Coast Research Laboratory Museum, Catalog Number GCRL 26632. Acknowledgments I thank Mr, Steven Carter of Biloxi, Mississippi, who captured the anomalous specimen and made it available for examination. Special thanks to Robin Overstreet who reviewed the manuscript and offered helpful suggestions. Much appreciation is extended to Rena Krol for providing photographic expertise and to Gina Deilrick and Dale Fremin for word processing assistance. This work was supported in part by the U.S. Fish & Wildlife Service, Sport Fish Restoration, Atlanta, GA (Project No. F-91), through the Mississippi Department of Wildlife, Fisheries and Parks, Bureau of Marine Resources (now the Mississippi Department of Marine Resources). Figure 1. Frontal view of the pugheaded cobia {R. canadum). Figure 2. Head of the pugheaded cobia (R. canadum). Figure 3. Head of a non-pugheaded cobia (R. canadum). 144 Pugheaded Cobia TABLE 1 Comparison of measurements of the head of the pugheaded cobia with the head of a non-pugheaded cobia (each fish 1110 mm FL^). Percentage of FL^ Measurements Pugheaded Non-Pugheaded Head length^ 23.8 24.1 Head width 19.8 16.4 Depth of head 20.8 15.9 Least bony interorbital width 13.5 12.7 Length of orbit 2.5 2.4 Length of mandible 9.7 10.2 Snout length 3.6 7.8 ^Fork length (FL) measured from anterior tip of lower jaw to fork of caudal fin. ^Measured from anterior tip of lower jaw to the most distanl point of the opaicular membrane. Literature Cited Bortone, S.A. 1972. Pugheadedness in the pirate perch, Aphredoderus sayanus (Pisces: Aphredoderidae). with implications on feeding. Chesapeake Sci 13(3):23 1-232. Burgess, G.H, and FJ. Schwartz. 1975. Anomalies encountered in freshwater and marine fishes from the eastern United States. Assoc South Biol 22(2):44. Dawson, C.E. 1964. A bibliography of anomalies of fishes. Gulf ResRepl(6):308-399. . 1966. A bibliography of anomalies of fishes. Suppl. 1. Gulf Res Rep2(2):169-176. . 1971. A bibliography of anomalies of fishes. Suppl. 2. Gulf Res Rep3(2);215-239. Dawson, C.E. and E. Heal. 1976. A bibliography of anomalies of fishes. Suppl. 3. Gulf Res Rep 5(2):35-41 . Franks, J.S. and J.T. McBee. 1992. Age and growth in cobia, Rachycentron cartadum^ from the northeastern Gulf of Mexico. In: Franks, J.S.» T.D. Mcllwain, R.M. Overstreet, J.T. McBee, J.M. Lotz, and G. Meyer, Investigations of cobia, Rachycentron canaduni, in Mississippi marine waters and adjacent Gulf waters. Gulf Coast Res Lab, Ocean Springs. MS 39566-7CKX). Final rpt to MS Dept WildJ.Fish and Parks/ B urMar Res and US Fish and Wildl Serv, Atlanta, G A 30303, Proj No F-91, p 1“6 to 1-60. Gudgcr,E.W. 1928. Guillaume Rondelefs pugheaded carp. Am Mus Nat Hist 28(1):102-104. . 1930, Pugheadedness in the striped sea bass, Roccus lineatus, and in other related fishes. Bull Am Mus Nat Hist 61(1):1-19. Hickey, C.R., Jr. 1972. Common abnormalities in fishes, their causes and effects. NY Ocean Science Laboratory Tech Rpt 0013. Hubbs, C.L. and K.F. Lagler. 1964. Fishes of the Great Lakes region. Revised ed, Univ Mich Pr, Ann Arbor, Mich. 213 p. Lotz, J.M., R.M, Overstreet, and J.S. Franks. 1992. Reproduction of cobia, Rachycentron canadum, from the northeastern G ulf of Mexico. In: Franks , J .S . , T.D. Mcllw ain . R.M. Overstreet, J.T. McBee, J.M. Lotz, and G. Meyer, Investigations of cobia,Rachycentroncanadum, in Mississippi marine waters and adjacent Gulf waters. Gulf Coast Res Lab, Ocean Springs, MS 39566-7(XX). Final rpt to MS Dept Wildl, Fish and Parks/Bur Mar Res and US Fish and Wildl Serv, Atlanta, GA 30303, ftoj No F-91. p 2-1 to 2-42. Mansucti.RJ. 1960. An unusually largepugheaded striped bass, Roccus saxatiHs, from Chesapeake Bay, Maryland. ChesapoakcSci 1(2):11 1-113. Rose, C.D. and A.H. Harris. 1968. Pugheadedness in the spotted seatrout. Quart J Fla Acad Sci 31(4):268-270. Schwartz. F.J, 1965. A pugheaded menhaden from Chesapeake Bay. Underwater Nat 3(1 ): 22-24. Shariff,M.,A.T.Zainuddin, and H. Abdullah. 1986. Pugheadedness in bighead carp,Arisiichihysnobilis (Richardson) . J Fish Dis 9:457-460. Sindeimaiin, F.J. 1977. Deformities in striped bass. In: C.J. Sindennann (cd.), North American Aquaculture, p 285-287. Elsevier Sci PublCo, Amsterdam. 145