1 80 NOAA Technical Report NMFS 140 



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BRYOZOA 



Figure 190 

 Geographic distribution of Bryozoa: A — number of specimens per square i 

 of bottom; B — biomass in grams per square meter of bottom. 



The percentage of samples containing bryozoans gen- 

 erally decreased with increasing water depth. The high- 

 est incidence of occurrence (19%) was in the shallow- 

 est depth class. At depths greater than 500 m, they 

 occurred in from to 5% of the samples (Table 15). 



Relation to Sediments 



Brvozoans were especially common in the hard, coarse 

 substrates that afforded suitable surfaces for attachment. 

 In addition, they were also found in smaller quantities in 

 the soft fine-grain sediments but attached to hard bio- 



genic materials, occasional pieces of gravel, or man-made 

 debris (Tables 16, 18; Fig. 193). Shell substrate seemed 

 particularly suitable in as much as it yielded an average of 

 over 300 colonies/m 2 and an average biomass of nearly 17 

 g/m 2 . Moreover, bryozoans made up over 25% of the 

 total number of specimens and 7.5% of the biomass of the 

 total benthic fauna in shell substrates (Tables 17, 19). 

 Gravel substrates ranked second in quantity, with an aver- 

 age density of 75 colonies/nr and a biomass of 7.4 g/ni". 

 Quantities were low (less than 6 colonies and 0.4 g/nr ) in 

 the remaining four sediment types. 



