158 



NOAA Technical Report NMFS 140 



56%), while the other depth classes had fre- 

 quencies over 15% (Table 15). 



Relation to Sediments 



Cumaceans occurred in all sediments found 

 in the region hut in significantly different 

 proportions. Sand, sand-silt, and gravel con- 

 tained the greatest numbers of individuals, 

 with mean densities of 45, 18, and 11/m , 

 respectively; shell and silt-clay sediments 

 yielded moderate mean densities (8 and 7/ 

 m L> , respectively), with smallest (1/m 2 ) 

 amounts in till substrates (Table 16; Fig. 157). 



The trend for biomass was essentially simi- 

 lar to that of density but at much reduced 

 levels (Table 18; Fig. 157). Sand, shell, and 

 sand-silt contained mean biomasses of 0.20, 

 0.08, and 0.06 g/m 2 , respectively, while the 

 values for gravel, till, and silt-clay were 0.06, 

 0.01. and 0.03 g/m 2 , respectively. 



The frequency of occurrence of cum- 

 aceans ranged from 50 to 26%, in samples 

 from sand, sand-silt, and gravel and was be- 

 tween 14 and 22%< in the other sediment 

 types (Table 20). 



Relation to Water Temperature 



Both measures of cumacean abundance showed a bi- 

 modal trend in relation to annual range in bottom 

 water temperature. The greatest numerical abundance 

 ( "><> irr ) and biomass (0.26 g/m 2 ) occurred where tem- 

 perature range was moderate (8-11.9°C), followed by 



another peak in areas experiencing a somewhat higher 

 ( 16-19. 9°C) range where high density (44/nf) but 

 considerably lower (0.09 g/m 2 ) biomass occurred 

 (Tables 21, 23; Fig. 158). Density was also relatively 

 high in the two other high temperature range classes 

 (12-15.9° and >20°C) but fell off considerably in the 

 more stable temperature regimes with ranges between 



