6-15 



Streblospio benedicti and Capitella capitata are generally recognized as 

 belonging to this group (Fisher and McCall, 1973) and have even been 

 categorized by some authors as "pollution-indicators" (Dean, 1970; Pear- 

 son and Rosenberg, 1978; Reish, 1961 and Wass, 1967), although the 

 severe physical stresses that favor their presence need not be x^ollution 

 related. 



Some indication of the extent to which an area has been 

 degraded by pollutants is provided through examination of the number of 

 species representing each of the three major benthic groups: poly- 

 chaetes, molluscs, and crustaceans. Organisms living in an unpolluted 

 habitat generally represent a wide variety of both feeding types and 

 life strategies. As a habitat becomes progressively degraded by pollu- 

 tants, this trophic and biological variety is reduced. In heavily 

 impacted habitats , organisms which biologically concentrate pollutants 

 such as carnivores or tubicolous filter feeders tend to be eliminated 

 leaving primarily surface deposit feeders. Reish (1972) , gives examples 

 showing that impacted areas are usually dominated by near-surface depo- 

 sit feeding polychaetes and that filter feeding molluscs and crustaceans 

 are reduced. This overall result can be used to evaluate, strictly, on 

 a comparative basis, the polychaete : mollusc : crustacean species ratio 

 of New Haven Harbor, 



The combined New Haven species list contains a polychaete : 

 mollusc : crustacean species ratio of 1.2 : 0.8 : 1.0, which is not 

 indicative of a strongly stressed area. The P : M : C ratio for the 

 more characteristic abridged list, however, is 1.2 : 1.0 : 0.7 which 

 shows a decrease in richness of crustaceans. For comparison, the 

 ratios for the two Raritan Bay studies were 1.6 : 0.6 : 0.8 (McGrath, 

 1974) and 1.3 : 1.0 : 0.8 (Dean, 1976). Although the decrease in crus- 

 taceans is seen in only one of the two studies, the relative increase in 

 polychaetes is obvious. In Clinton Harbor, a relatively pristine Conn- 

 ecticut estuary, the ratio was 1.0 : 0.8 : 1.2, indicating that, under 



