Composition and Distribution of Macrobenthic Invertebrate Fauna 



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SCOTIA MAINE BANK NEW ENGLAND SLOPE NEW ENGLAND 



SHELF SLOPE 



GEOGRAPHIC AREA 



Figure 135 

 Density and biomass of Arthropoda in each of the six geographic areas. 



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Bank out onto Georges Slope. One patch of moderate 

 density was located in Great South Channel. 



Among the standard geographic areas, sea spiders 

 were found in all but the Southern New England Slope. 

 The shallow-water shelf areas, Nova Scotia, Southern 

 New England Shelf, and Georges Bank, yielded higher 

 mean densities (0.8-0.3/m 2 ) than the deeper Gulf of 

 Maine and Georges Slope localities (Table 6; Fig. 141). 



Mean biomass showed a diminishing trend from 

 northeast to southwest, ranging from 0.02 to <0.01 g/m 

 (Table 8; Fig. 141). 



Frequency and of occurrence was highest in Nova 

 Scotia and on Georges Slope and lower in the other 

 subareas (Table 10). 



Bathymetric Distribution 



Pycnogonids were absent in the 200-499 m and 2,000- 



3,999 m depth zones but present in small quantities in 



the other zones. Mean densities were highest (0.6/m ) 

 in the two zones between and 49 m depth and dimin- 

 ished as depth increased (Table 11; Fig. 142). Lowest 

 density (0.1/m ) occurred in the deepest depth zone 

 that they occupied (1,000-1,999 m). 



Biomass of pycnogonids was low in all depth zones in 

 which they occurred, ranging from <0.01 to only 0.03 

 g/m 2 (Table 13; Fig. 142). The highest biomass was in 

 the 100-199 m depth zone. 



Frequency of occurrence of sea spiders in samples 

 was fairly uniform in most depth zones, ranging from 2 

 to 4%; however, 9% of samples in the 500-999 m zone 

 contained specimens (Table 15). 



Relation to Sediments 



Shell is the only sediment type in which pycnogonids 

 were not found. They were most prevalent (by a wide 

 margin) in both measures of abundance in gravel, where 



