5-20 



Charaoter'istic Taxa 



Of the species considered to be characteristic, seven were 

 characterized by high frequency of occurrence {> 19 % overall) (Table 5- 

 5) but generally low density. These taxa include Nereis succinea, 

 Styllochus ellipticus , Crepidula spp. , Electra crustulenta, Sahella 

 micropthalma, Metridium senile, and Molgula spp. Each will be briefly 

 discussed with reference to percent occurrence and short-term panel 

 settlement. 



Dominant taxa, characterized by high numerical abundance as 

 well as high frequency of occurrence, are treated in more detail. 

 Included as dominants are Balanus spp., Obelia longissima, Polydora 

 ligni , Corophium insidiosum. Teredo navalis , and Mytilus edulis . Cras- 

 sostrea virginica is also discussed because of its economic importance 

 in the harbor. The discussion for each relates life-history and thermal 

 tolerances to seasonal and spatial distributions, including occurrence 

 in New Haven Harbor and greater Long Island Sound. Figures 5-6 through 

 5-14 depict spatial/temporal distributions and abundances. The latter 

 are converted from absolute numbers of individuals or percent coverage 

 to 1, 2, 3 or 4 for consistency in presentation (see key. Figure 5-7). 

 For Balanus, all the different taxonomic levels encountered in the study 

 period are presented. Balanus spp. was used in 1975 and 1976 only. S. 

 crenatus occurred only in 1974. 



Selected Taxa 



Nereis succinea ranked second in percent occurrence (75% 

 overall) and was consistently present at all stations (Tables 5-4, 5-5) . 

 Numbers were seldom great but this motile polychaete was a consistent 

 component of the harbor fouling panel community. It occurred from July 

 through October on short-term panels (Figure 5-3) . 



Text continued on page 5-29 



