RESULTS 



Faunal Composition 



A total 214 taxa were identified (Appendix Table 2). Since 

 some taxa were identified only to phylum (Porifera, Nemertea) 

 and since some taxa identified to genus may include several 

 species, the total number of taxa is conservative. Of the 

 number of taxa, ~24. 3% were molluscs, 27.1% arthropods, 

 24.3% polychaetous annelids, 10.7% echinoderms, and 13.6% 

 miscellaneous taxa, including sipunculids, coelenterates, 

 nemerteans, ectoprocts, ascidiaceans, pogonophorans, and 

 hemichordates. Biomass (wet weight g/m 2 ) and density 

 (no./m ; ) are presented in Appendix Tables 3 and 4. About 

 190,000 individuals and 15,500 g of specimens were collected. 



Total Faunal Biomass and Density 



Average biomass and density per station for total fauna were 

 245.7 g/m 2 and 3,008 individuals/m 2 , respectively. Biomass in 

 the shallow central stations generally ranged from 100 to 999 

 g/m 2 (Fig. 4). Biomass decreased to a range of 1-100 g/m 2 in 

 slightly deeper water and then increased again to 100-999 g/m 2 

 between 60 and 100 m. Below 100 m on the western side of the 

 study area, biomass again decreased to < 100 g/m 2 , but 

 biomass was still in the 100-999 g/m 2 range on the eastern side 

 to almost 200 m. Molluscs, polychaetes, and shallow-water 

 echinoderms contributed heavily to the highest values of 

 biomass. 



The density pattern for total fauna was more irregular than 

 for biomass (Fig. 5). A range of 1,000 to > 3,000 m 2 occurred 

 in shallow water. A major portion of the area contained den- 

 sities of 1,000-2,999/m 2 . Lowest densities (1-999/m 2 ) were 

 recorded below MOO m. Crustacea, primarily amphipods, and 

 polychaetes contributed greatly to the highest density values. 



Biomass and density were distributed among the major taxa 

 as follows: 





Biomass 



Density 





{g/m') 



(no./m 2 ) 



Annelida 



10.9% 



20.3% 



Mollusca 



56.7% 



5.9% 



Crustacea 



4.1% 



62.5% 



Echinodermata 



21.3% 



7.0% 



Misc. taxa 



7.0% 



4.3% 



Stations were grouped into ranges of depth, temperature, 

 median sediment size, and silt-clay (Maurer and Wigley foot- 

 note 6). Mean biomass and density were calculated for those 

 ranges and summarized. A depth range of 40-80 m, tempera- 

 ture 6.0°-7.9°C, <(» 2.0-3.99, and 0.6% silt-clay comprised the 

 main distribution of biomass (Fig. 6). The principal distribu- 

 tion of density was accounted for by a depth range of 0-100 m, 

 temperature 6.0°-9.9°C, <|> 1.0-3.99, and 0-40% silt -clay. Mean 

 biomass and density declined with depth but the correlations 

 were low (R = -0.20). 



7,1 



41°- 



40°- 



Ll ' ., I I l_ 





-l 



,' MARTHAS VINEYARD 



ULUUK * 



ISLAND 'a,' 1 _ 

 if ° 



> 4 





mm 



l-99.9g/m 2 

 IOO-999 9g/m2 



7 /ffh > 1 ,000 g/m* 



YF~ r 



~\ i i i 7'0° r 



Figure 4. — Quantitative distribution of biomass 

 (g/m 1 ) for all macrobenthic invertebrates combined 

 off Martha's Vineyard, Mass., from samples collec- 

 ted at stations (o), June 1962. 



