132 



NOAA Technical Report NMFS 140 



A comparison of average density and average bio- 

 mass in the various areas indicates that scaphopods are 

 relatively large in Nova Scotia and on Georges Bank, 

 and relatively small in the Southern New England Slope 

 area. 



Frequency of occurrence was low (4 to 7% of the 

 samples) on Georges Bank and the Southern New En- 

 gland Shelf, and moderate (33 to 46% of the samples) 

 in all other areas (Table 10). 



Bathymetric Distribution 



Scaphopods were taken at depths ranging from 19 to 

 2,329 m. They occurred in low density (0.1 and 0.2 

 individual/m 2 ) in both shallow water and deep water 

 but were present in relatively high densities (10 to 14 

 individuals/m' 2 ) in moderately deep water, 100 to 1,000 

 m (Table 11; Fig. 1 25) . Increases and decreases in 

 density about their center of abundance were surpris- 

 ingly consistent and well correlated with changes in 

 depth. 



The biomass of scaphopods (Table 13; Fig. 125) was 

 small (<1 g/m'-') in all depth classes, but changes in 

 abundance relative to changes in water depth were 

 similar to that described above for numerical density. 

 Average biomasses in the shallowest and deepest bat In- 



metric classes were <0.01 g/m 2 . The average biomass 

 was largest (0.17 to 0.98 g/m 2 ) in moderately deep 

 water (100 to 2,000 m). Because of the small size and 

 low density of this taxonomic group, it contributed a 

 rather small share (1.6% or less) of the total benthic 

 biomass in any depth class (Table 14). 



Scaphopods occurred in a moderate share (35 to 

 59%0 of the samples collected from depths between 

 100 and 2,000 m (Table 15). At depths both shallower 

 and deeper, they occurred in less than 10% of the 

 samples and in the two shallowest depth classes, they 

 were present in only 1% of the samples. 



Relation to Sediments 



Scaphopods were present in all types of bottom sedi- 

 ments sampled, but were clearly more abundant (11 to 

 26 individuals/m 2 ) in the shelly and Fine-grained sedi- 

 ments than in the coarse types (Table 16; Fig. 126). 

 Sand and gravel bottoms yielded the lowest (1.8 and 

 2.0/m 2 ) densities. The percentage of the total faunal 

 density composed of scaphopods was small (2.2% or 

 less) in all types (Table 17). 



Differences in biomass from one type of bottom to 

 another were less pronounced than they were for den- 

 sity; however, the trend was the same (Table 18; Fig. 



