Composition and Distribution of Macrobenthic Invertebrate Fauna 



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 PERCENT ORGANIC CARBON 



Figure 195 

 Density and biomass (if Bryozoa in relation to sediment organic carbon. 



Brachiopods occurred in 54 samples (5% of total). 

 Their numerical density averaged 4.5 individuals/m 2 , 

 and their biomass averaged 0.89 g/m- (Table 5). 



Geographic Distribution 



Brachiopods were restricted to the northeastern sector 

 of the study area, the only region in which suitable 

 habitats were found (Fig. 196). Numerical density was 

 usually low (<49 individuals/m ) over most of their 

 range as was biomass (<10 g/m 2 ); small areas of moder- 

 ate (between 50 and 100/m 2 ) density and biomass (10 

 to 63 g/m 2 ) occurred in south-central Gulf of Maine 

 adjacent to the northern edge of Georges Bank and on 

 the Nova Scotian shelf. Significant densities (between 

 100 and 490/ m 2 ) did occur in a few places, notably at 

 the mouth of the Bav of Fundy. 



Among the six standard geographic areas brachio- 

 pods were restricted to Nova Scotia, the Gulf of Maine, 

 and Georges Slope. Largest average density (22/m 2 ) 

 and biomass (3.68 g/m 2 ) occurred off Nova Scotia fol- 



lowed by Gulf of Maine (9.5/m 2 and 2.12 g/m 2 ); 

 Georges Slope contained insignificant quantities (Tables 

 6, 8; Fig. 197). 



Twenty-one percent of the samples off Nova Scotia 

 contained brachiopods versus 12% in the Gulf of Maine; 

 only 2% of the Georges Slope samples yielded speci- 

 mens (Table 10). 



Bathymetric Distribution 



Brachiopods were taken at depths between 51 and 690 

 m. Very few occurred in water deeper than 499 m 

 (Tables 11, 13; Fig. 198). Largest average density and 

 biomass were found at depths between 200 and 499 m 

 in so-called upper slope depths; there density averaged 

 17 individual/m 2 and biomass nearly 4 g/m 2 . Both 

 average density and biomass decreased significantly with 

 decreasing depth above 200 m. 



Frequency of occurrence of brachiopods in the 

 samples was moderate to low. The highest frequency 

 was in the 200-499 m depth class at 14%; the rate 



