178 



NOAA Technical Report NMFS 140 



19.9°C; beyond this, in the 20.0-23.9°C range 

 class, both measures declined (Tables 21, 23; 

 Fig. 188). Average density and biomass (0.9/m 2 

 and 0.47 g/m 2 , respectively) were lowest in the 

 narrowest temperature range class (0- y 3.9°C) 

 and generally increased with broadening tem- 

 perature range, peaking at 23.2/m'-' and 4.26 g/ 

 m 2 in the 16.0-19. 9°C range class. Intermediate 

 values of both measures occurred where the 

 temperature range was broadest. 



The frequency of occurrence of decapods 

 in the samples in the various temperature 

 range classes parallels the trend established 

 for density and biomass, ranging from 6% in 

 the narrowest range class to 53% in the 16- 

 9.9°C class, and dropping to intermediate (18%) 

 levels in the broadest range class (Table 25). 



Relation to sediment organic carbon 

 Decapods were absent in areas where no mea- 

 surable organic carbon occurred in the sedi- 

 ments, as well as in areas with the highest 

 recorded amounts. They were present in the 

 five organic carbon content classes between 

 0.01 and 2.99% where average density and bio- 

 mass described U-shaped distributions (Tables 

 26, 28; Fig. 189). Average density ranged from 

 nearly 8 to 0.5 individuals/m 2 and average bio- 

 mass from 4.15 to 0.30 g/m . Values were high- 

 est at the extremes of the carbon content classes 

 in which they occurred and fell to the lowest 

 levels in the middle carbon content classes, 

 slightly biased toward the higher end. 



Frequency of occurrence of decapods in 

 the samples described a distribution similar 

 to density and biomass. Occurrence was mod- 

 erate, ranging from 4 to 32%, but in this 

 instance was biased slightly toward the lower 

 end of the content range (Table 30). 



tr uj 

 uj ct 



CD < 



3° 



2 V) 



< 



J- 3 

 UJ o 



SAN0- 

 SILT 



SILT- 

 CLAY 



GRAVEL TILL SHELL SAND 



BOTTOM SEDIMENTS 



Figure 187 

 Density and biomass of Decapoda in relation to bottom sediments. 



Bryozoa 



Bryozoans are sessile colonial animals most frequentlv 

 found attached to rocks, shells, ship bottoms, pilings, 

 firm outer surfaces of other animals, and other similar 

 hard substrates. Their distribution in the study area was 

 somewhat patchy owing to their requirement for a firm 

 substrate and moderate to strong water currents. The 

 currents transport to them their main food supply, 

 minute plankton, principally diatoms. 



These organisms contribute a significant number 

 (more than one hundred) of species to the New En- 

 gland benthic fauna. The majority of these species be- 

 long to the class Gymnolaemata, order Cheilostomata. 



The calcareous encrusting forms were especially nu- 

 merous, but the chitinous foliaceous types were usually 

 the largest specimens encountered. 



Although the Bryozoa constitute a major phylum in 

 species diversity and are a major contributor to the 

 biomass in certain localized habitats, their small size 

 and patchv distribution rather severely limited their 

 contribution to the total benthic fauna. In terms of nu- 

 merical density, ectoprocts made up 1% of the total fauna 

 and contributed only 0.7% of the total biomass (Table 3). 



Bryozoans occurred in 119 samples (11% of total). 

 Their density averaged 15.7/m 2 . Their biomass aver- 

 aged 1.29 g/m 2 (Table 5). 



