7-16 



surface food sources (TRIGOM, 1973) . Its predators are similar to those 

 described for Mya and Ccjmina . 



These three dominant bivalves were found in greatest numbers 

 and with the highest frequency of occurrence at Long Wharf Station. 

 Bivalves were numerous at Sandy Point Station from 1971 through 1973 but 

 subsequently declined. 



The only dominant gastropod, the mud snail (Ilyanassa obso- 

 leta) , was almost exclusively found at Sandy Point. Its presence was 

 highly variable over time (Figure 7-2). In two years, 1972 and 1977, 

 they were scarce or absent. By contrast, they were especially numerous 

 from 1974 through 1976. Sediment changes that enhanced the s\ibstrate 

 for occupation by Ilyanassa and discouraged the settlement of bivalves 

 may have occurred at that station in 1972-1974. According to Jenner 

 (1957) , however, variable distributions are common. Reproduction of 

 this deposit feeder (Scheltema, 1964) occurs in the sizmmer when females 

 deposit encapsulated eggs on a hard substrate where the embryos develop 

 until hatching — usually (depending on temperature) within a month. 

 Released larvae have a planktonic stage and eventually settle and meta- 

 morphose (Scheltema, 1967) . It is probable that the proximity of a rock 

 jetty to the transect and the s\ibstrate it offers for egg capsule depo- 

 sition is a factor influencing the occurrence of this gastropod on the 

 Sandy Point transect. 



The sandworm, {Nereis succinea) , the most-common large poly- 

 chaete in New Haven Harbor, is also considered to be the most ubiquitous 

 polychaete in Long Island Sound intertidal areas (Sibley and Sibley, 

 1969) . Nereis was common in most years at all stations, especially in 

 October. May population abundances at East Shore were low in all years, 

 and at Sandy Point and Long Wharf relatively high abundances during the 

 period 1971-1973 decreased from 1974 through 1977 (Figure 7-3) . Nereis 

 succinea breeds in the water column by swarming in the evenings during 

 summer months. Its larvae are planktonic and mature to deposit-feeding 

 adults. Wass (1967) included Nereis succinea as one of a number of 



