29 



The proportion of biomass contributed by major taxonomic groups (e.g., 

 oligochaetes, polychaetes, etc.) differed both among sites and over time (Figure 3-17). In 

 1991 and 1992, molluscs provided approximately 50% of total biomass at the constructed 

 intertidal flat while polychaetes and crustaceans, respectively, made lesser contributions. 

 By 1994 molluscs accounted for 90% of all biomass at the constructed flat, however, this 

 value fell to 29% in 1998 when crustacean biomass increased from 15% to 40% of total 

 biomass. At the reference area, polychaetes were the overwhelming dominant in 1991 

 (68%), but were replaced by molluscs (53-93%) in subsequent samples. As at the 

 constructed flat, the highest proportion of mollusc biomass was found in 1994. 



Figure 3-17. Sheep Island Infaunal Biomass Structure. 



100 





Misc 



/y\ Mollusc 



Crustacea 



^H Oligochaaa 



^H Pol3rdhBieta 



1991 1992 1994 1998 

 Constructed Flat (DM) 



1991 1992 1994 1998 

 Reference (REF) 



Together, the assemblage structure parameters indicate that a diverse and abundant 

 infaunal assemblage was quickly established at the constructed intertidal flat. The absence 

 of site or site by year differences in biomass values also suggests that the assemblage 

 developed rapidly, achieving and maintaining levels comparable to the reference area. The 

 overall dominance of biomass by molluscs and the tendency for periods of particularly high 

 dominance to be identical at both sites (e.g., 1994) also indicates a high degree of 

 similarity between sites. 



Ecological Monitoring of a Constructed Intertidal Flat at Jonesport, Maine 



