6-51 



greater fidelity as Pagurus occurs as a codominant only within this 

 cluster, while Tellina reaches its greatest dominance here. Streblospio 

 and Glycera are much more widespread in the harbor and appear as com- 

 ponents of many communities. 



The third and largest cluster, and the one which exhibits the 

 highest affinities, occupies the central portion of Morris Cove. 

 Included in this group are Stations B, E, F, I, H and UN, which are in 

 the shipping channel a short distance to the north of the Cove. This 

 group of stations produced a very distinct cluster located in soft silt- 

 clay substratum which may indicate an area of greater physical stability 

 than the sediments characteristic of the (A, C, G) cluster. 



The large group of stations in the central portion of Morris 

 Cove exhibits the most distinct and consistent community in the harbor. 

 The dominant species at each of the six component stations of this group 

 is Nephtys incisa, a species which showed both constancy and fidelity 

 for this cluster. The subdominant species at each of the six stations 

 was one of three small bivalves, Tellina agilis, Nucula proxima or 

 Mulinia lateralis . The ubiquitous pair of polychaete species {Glycera 

 and Streblospio) was also present at nearly every station. Apparently, 

 however, the deterministic faunal component of this community is the 

 polychaete, Nephtys, accompanied by one of three bivalves. 



One additional aspect of this Nephtys community that is some- 

 what unusual is the presence of the tiibicolous amphipod, Ampelisca spp. , 

 at most of the stations. No amphipod species was present as a co- 

 dominant in any of the other clusters. Since amphipods, particularly 

 Ampeliscid amphipods, have become recognized as extremely pollution- 

 sensitive, their presence in these Morris Cove samples indicates that 

 this area is relatively unpolluted in relation to the rest of the har- 

 bor, particularly in regard to petroleum hydrocarbons. 



An additional minor cluster of two spatially separated sta- 

 tions 8N and 13N, was also recognized. This small group is of limited 



