Composition and Distribution of Macrobenthic Invertebrate Fauna 51 



i$& 



% 



* 





t. 



jr-r, Kt 



Figure 18 

 Medium coarse sand bottom at a depth of 87 m on the western Nova Scotia shelf. This locality also 

 contains some fine angular to rounded gravel to 7 cm in size. Bivalve shell fragments litter the bottom; 

 an intact mussel valve is visible in the upper right-center portion of the frame. The camera tripping 

 weight is visible at upper left-center. Photograph was taken at station 1165c. located at lat. 44°09' N., 

 long. 66°29' W. 



The percentage occurrence of each taxonomic group 

 in samples in each sediment type is presented in 

 Table 20. 



Photographs of the sea bottom (Figs. 18 to 24) taken 

 with the photographic system in the Campbell Grab 

 show the sediment surface and associated fauna in dif- 

 ferent bottom types in different subareas within the 

 New England region. Sediment types range from coarse 

 (gravels and cobbles) to fine (silty sands). The camera- 

 tripping weight, visible in each photograph, serves 

 as a possible indicator of the amount of silt-clay contained 

 in the sediment depending on the quantity of material 

 disturbed and entering into suspension upon disturbance. 



Relation to Water Temperature 



The abundance of the New England region macro- 

 benthos, in general, was related directly to the annual 

 range in water temperature. In areas with a small an- 

 nual range in water temperature, the density of animals 

 was low and the biomass small. Conversely, where the 

 annual range in water temperature was large, the den- 

 sity of animals was high (Tables 21, 22; Fig. 25), and 

 biomass large (Tables 23, 24; Fig. 25). In areas subject 

 to annual water temperature ranges of less than 4°C, 

 average density was only 431/irr and biomass only 

 46 g/m 2 . Although there are some inconsistencies, in 



