80 



NOAA Technical Report NMFS 140 



(1.2 to 2.1 g/m 2 ). Relatively high quantities 

 (8 to 18 g/m 2 ) occurred in outer shelf and 

 upper slope depths (Table 13; Fig. 47). The 

 proportion of the total benthos contributed 

 by Zoantharia was low at all depths except 

 between 100 and 500 m where members of 

 this group made up 13 to 19% of the total 

 biomass (Table 14). 



Frequency of occurrence of Zoantharia in 

 samples was moderate (16 to 33%) at depths 

 down to 500 m. At depths greater than 500 

 m they occurred in only 8 to 18% of the 

 samples (Table 15). 



Relation to Sediments 



Zoantharians were present in all types of 

 bottom sediments sampled (Fig. 48). High- 

 est density (43/m 2 ) occurred in sand sedi- 

 ments, moderate densities (9 to 14/m 2 ) in 

 gravel and sand-silt, and low densities (2 to 3/ 

 trr) in all other types (Tables 16, 17). 



In terms of biomass the relationship was somewhat 

 different. The largest quantities occurred in sand-silt, which 

 was due mainly to the presence of large burrowing anemo- 

 nes. Rather large quantities, mostly actinarians, were 

 present in gravel. Relatively small biomasses occurred in 

 all other types of bottom sediments (Tables 18, 19). 



The frequency of occurrence of this diverse group of 

 animals was moderate and rather uniform in all types of 

 bottom sediments. The percentage of samples contain- 

 ing Zoantharia in each of the different bottom types 

 ranged from 17 to 35 (Table 20). 



Relation to Water Temperature 



The average density of zoantharians in relation to the 

 annual range of bottom water temperature occurring in 

 different regions of the study area varied from 2 to 98/ m 2 



(Tables 21, 22; Fig. 49). Density was highest (98/m 2 ) in 

 areas with a moderate (12°-15.9°C) temperature range, 

 and densities decreased to about 2 to 4/m where the tem- 

 perature range was both narrow (<4°C) and broad (>20°C) . 

 The relation between zoantharian biomass and tem- 

 perature range differed from that of density. Generally 

 biomass was high (4 to 8 g/m 2 ) where the temperature 

 range was narrow or moderately narrow (<12°C), and 

 the general trend was a decrease in biomass associated 

 with a broadening of the temperature range (Table 

 23). This correlation is revealed more clearly bv the 

 percentage of the total benthic fauna that is made up 

 by zoantharians (Table 24). Where the temperature 

 range was less than 4°C, zoantharians contributed 18% 

 of the total benthos. Their contribution decreased as 

 the temperature range broadened, forming only 0.2% 

 of the benthos where the range was >20°C. 



