Composition and Distribution of Macrobenthic Invertebrate Fauna 



145 



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PERCENT ORGANIC CARBON 



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Figure 139 

 Density and biomass of Arthropoda in relation to sediment organic carbon. 



Other studies (Wigley and Mclntyre. 19(34) revealed 

 that ostracods, including specimens as small as 75 mi- 

 crons or less, are not abundant in the offshore South- 

 ern New England region. Their average density there 

 was only slightly more than 1 individual/m . 



Ostracods were taken at only five stations (0.5% of 

 total) situated in diverse localities, all in offshore waters 

 (Fig. 147). Two of the stations were situated on the 

 Nova Scotia shelf, and one station was situated at each 

 of the following locations: the Gulf of Maine, the conti- 

 nental slope south of Georges Bank, and the continental 

 rise east of New Jersey. Density of these ostracods averaged 

 <0.1/rrr and their biomass <0.01 g/irr (Table 5). 



Water depths at which ostracods were found ranged 

 from 61 to 2,682 m. Their average density was slightly 

 higher at depths below 200 m than on the continental 

 shelf (Tables 11,13). 



Ostracods occurred in three types of bottom sedi- 

 ments: gravel, sand-silt, and silt-clay. Their density was 

 about equal in each type (Tables 16, 18). 



Members of this group were found only in areas 

 where the temperature range was below 8°C. Although 

 their density in all areas was low, it was slightly higher 

 where the temperature range was less than 4°C than in 

 areas where slightly higher (4-7.9°C) ranges prevailed 

 (Tables 21, 23). 



Ostracods occurred where sediment organic carbon 

 content levels ranged between 0.01 and 0.99%. Densi- 

 ties were somewhat greater at the higher levels than at 

 the lower ones (Tables 26, 28). 



Cirripedia — Barnacles were generally sparse and, ex- 

 cept in a few local areas, made up a small proportion of 

 the total benthic fauna. In some favorable habitats, 

 such as rocky areas in shallow coastal waters and on 

 offshore banks subjected to relatively strong water cur- 

 rents, barnacles were common to very abundant (Table 

 3). Densities of nearly 8,000 individuals/m 2 and biom- 

 asses of over 1,000 g/m 2 were encountered. 



Members from two suborders, Balanomorpha (rock 

 barnacles) and Lepadomorpha (stalked barnacles), were 



