69 



Biomass 



2 

 Biomass of the 1.0 mm sieve fraction averaged 49.6 g/m on a wet 



2 

 weight basis. The range at individual stations was 1.8 to 191.0 g/m 



(Table 8) . In all cases animals weighing over one gram were excluded 



from the analysis. Annelids constituted 49.6% of the fauna in terms of 



wet weight. Arthropods, molluscs, echinoderms and miscellaneous phyla 



accounted for 19.3, 11.6, 1.9 and 17.6% of the biomass, respectively. 



There was considerable variation in total biomass between stations 

 but relative dominance of higher taxa was fairly consistent (Fig. 22 and 

 23). Annelids were biomass dominants at 43 of the 56 stations. 

 Arthropods were dominant at stations 2, 4 and 5 due to the abundance of 

 Ampelisoa agassizi and Haploops tubiaola and at stations 24 and 25 due 

 to Casoo bigelowi. Molluscs were also biomass dominants at only five 

 stations. These were stations 47 - 50 because of the presence of Nuoula 

 delphinodonta and Nassarius trivittatus and at the sparsely populated 

 station 43. Stations 18 - 20 in Portland Harbor were dominated in terms 

 of biomass by various miscellaneous taxa. 



Like density, biomass exhibits a strong positive correlation 

 (99.9%) with depth and a strong negative correlation (99.0%) with mean 

 grain size (Figs. 24 and 25). Furthermore, it is negatively correlated 

 with organic carbon (99.9%) (Fig. 26). In addition, biomass is also 

 positively correlated at the 99.9% level with density and number of 

 species per station. It is negatively correlated with all of the trace 

 metals. Three of these relationships, cadmium, chromium and zinc are 

 significant at the 95% level. Levels of significance for copper, nickel 

 and lead are 83, 89 and 79%, respectively. 



