12-37 



Intevtidal Benthos 



Overall abundances of intertidal benthic organisms at East 

 Shore, Long Wharf and Sandy Point for the 1971-1977 period are presented 

 in Section 7.0. There arc no substantial differences in the preoperational 



and operational populations at these three sites. Species diversity 

 (number of taxa collected) also remained similar in pre and post- 

 operational years. In general, however, highest number of taxa were 

 found in the Sandy Point area, followed by Long Wharf and East Shore. 



Intertidal samples in the Sandy Point area were dominated 

 numerically by the gem clam {Gemma gemma) , soft-shell clam [Mya arenaria) 

 and mud snail {Ilyanassa obsoleta) . Also present in large numbers were 

 polychaete worms. Nereis spp. and those of the family Spionidae and 

 Cirratulidae. Data indicate that there have been no major changes in 

 total numbers or species composition during the 1971-1977 period. 

 Polychaete worms and molluscs have been present both prior to and after 

 plant start-up. Gem clams have not been found in samples collected 

 after May 1974, when the sampling transect was changed. The absence of 

 this species is probably due to its localized breeding habits and the 

 change in substrate of the new transect. 



The bivalves Mya arenaria and Gemma gemma and polychaete worms 

 of the genus Nereis dominated the benthic fauna at the Long Wharf flats . 

 With the exception of reduced numbers of all species in October 1976 and 

 May 1977, numbers and species diversity have not changed substantially. 

 This decline during these two sampling periods is not believed to be 

 significant and is explained in Section 7.0. 



The East Shore area was generally the lowest both in number of 

 species and overall abundance. Polychaetes were the most consistently 

 present organisms, while bivalves also occurred. Both total ntjinbers and 

 numbers of species fluctuated both before and after plant start-up. 



