i i i 7|l ii 



„„, /' MARTHA'S VINEYARD ^jeESJ&rv) 1 



ri ISLAM". 



41°- 



Figure 5. — Quantitative distribution of individuals 

 (no./m 1 ) for all macrobenthic invertebrates com- 

 bined off Martha's Vineyard, Mass., from samples 

 collected at stations (o), June 1962. 



40°- 



,'' ' i Jr i 



-80 



<r^~-r' 



1000 METERS 



llllj I -999 9/m* 

 HH1 1000-2,999.9/m 2 



^j >3,000/m 2 



~\ 1 i : f\i r 



Polychaetous Annelids 



Many species of polychaetes were identified (Appendix 

 Table 2). The number of species is a conservative estimate 

 because recent work with a 0.5 mm mesh sieve has yielded 

 higher numbers of species (Maurer and Leathern 1980). Mean 

 biomass of polychaetes ranged from 0.1-39 g/m 2 throughout 

 most of the area to > 100 g/m 2 at a few stations (Maurer and 

 Wigley footnote 6). A biomass range of 40-99 g/m 2 was 

 measured directly south of Nantucket I. and Nantucket 

 Shoals. 



Polychaetes were more evenly distributed throughout en- 

 vironmental ranges than any of the major taxa (Fig. 6). Mean 

 biomass and density were negatively associated with tempera- 

 ture (R = -0.39, R = -0.39). A number of polychaete 

 species showed marked differential distribution. Maldanids 

 and Scalibregma inflatum occurred in shallow water and sand. 

 The latter species showed the same relationship over Georges 

 Bank (Maurer and Leathern 1980). In contrast, terebellids and 

 Sternapis scutata occurred in deeper water with fine-grain 

 sediment. 



Mollusca 



In terms of mean biomass and density, Mollusca contained 

 Scaphopoda (0.1 and 0.6%, respectively), Gastropoda (4.8 

 and 15.2%), and Pelecypoda (95.1 and 84.2%). Biomass ranged 

 from 0.1 to > 100 g/m 2 with the highest values directly south 

 of Nantucket Shoals and southwest of Nantucket I. (Maurer 

 and Wigley footnote 6). A depth range of 20-80 m, 6.0°-9.9°C,<|> 

 2.0-3.9, and 0-20% silt-clay comprised the main distribution 



of biomass (Fig. 6). Density distribution of Mollusca was very 

 different from biomass distribution because the most numerous 

 molluscan species were smaller than the main contributors to 

 biomass. Densities ranging from 100 to >400/m 2 occurred in 

 the central part of the study area between 60 and 100 m. This 

 central area was surrounded by densities ranging from 1 to 

 99/m 2 . The main distribution of density for molluscs encom- 

 passed 80-100 m, 7.0 o -10.9°C, <t> 3.0-5.9, and 20-100% silt-clay 

 (Fig. 6). Mean density of mollusca was positively associated 

 with grain size (R = 0.44). 



Scaphopoda. — The scaphopods Cadulus pandionis, C. ver- 

 rilli, and Dentalium occidentale were sampled only at deep sta- 

 tions (Maurer and Wigley footnote 6). Scaphopods occurred in 

 relatively low biomass (0.05-0.08 g/m 2 ) and density (3.3- 

 7.5/m 2 ) in water deeper than 200 m. Their distribution mainly 

 encompassed 10.0°-12°C, <j» 4.0-5.9, and 40-80% silt-clay (Fig. 

 6). 



Gastropoda. — Although biomass and density of gastropods 

 ranged from 0.1 to > 100 g/m 2 and from 1 to >400/m 2 , re- 

 spectively, there were only a few stations that contained > 100 

 g/m 2 or >400/m 2 (Maurer and Wigley footnote 6). Biomass 

 and density patterns of gastropods were very different (Fig. 6). 

 Biomass patterns were mainly influenced by large-to-inter- 

 mediate size, shallow water, sand-dwelling taxa {Colus, 

 Nassarius, Buccinum, Neptunea, Lunatia), and density was 

 influenced by smaller, deep-water, silt-sand and sandy-silt 

 species (Alvania carinata). There was a significant negative 

 association between density of gastropods and temperature 

 (R = -0.37). 



