40 NOAA Technical Report NMFS 140 



MEAN 

 NUMBER 



PERCENTAGE 

 COMPOSITION 



2.503 



2.232 



2.257 



272 



122 



75 



Figure 15 



Quantitative composition of the total macrobenthic invertebrate fauna in relation 

 to water depth. Mean number of individuals per square meter of bottom area, and 

 percentage composition, bv density, of the major taxonomic groups are shown. 



same as the changes in density (Tables 8, 9; Fig. 14A). 

 Southern New England Shelf and Georges Bank had 

 the highest average biomasses (267 and 234 g/m 2 ); 

 biomass was intermediate (178 and 127 g/m 2 ) in Nova 

 Scotia and the Gulf of Maine, and low (21 and 20 g/m 2 ) 

 on Georges Slope and Southern New England Slope. 



The percentage occurrence of each taxonomic group 

 in the samples in each geographic area is presented in 

 Table 10. 



Bathymetric Distribution 



One of the most striking relationships in the New England 

 region was the pronounced diminution in quantity of 

 macrobenthic invertebrates from shallow to deep water 

 (Tables 11, 12; Fig. 15). In the shallowest waters sampled 

 (0-24 m) the average density was 2,503/m 2 , whereas in 

 the deepest water (2,000-3,999 m) the density averaged 

 only 75/m . The decrease from one depth range to an- 



