4-33 



was made. Abundances usually remained at peak levels, with some fluc- 

 tuations, through June, and declined by July (1974 and 1975) or August 

 (1976 and 1977). Secondary abundance peaks, usually lower in magnitude 

 than the initial late-spring/early summer peak, occurred from August 

 through October 1974, in August 1975, from September through November 

 1976 and in September 1977. Although tidal and depth differences were 

 occasionally apparent, seasonality appeared to exert the strongest 

 influence on overall abundance estimates. 



New Haven abundances were similar but slightly greater than 

 those recorded at Millstone Point (Niantic Bay) (Figure 4-14) . Seasonal 

 abundance peaks occurred in the early summer at Millstone Point and 

 declined precipitously in the winter as at New Haven Harbor (Figure 4- 

 14) . In Block Island Sound, Deevey (1952a) found total abundances similar 

 to Millstone Point with an early summer maximum and winter decline (Fig- 

 ure 4-14c) . 



As in nearly all of the world's marine waters, the major 

 component of the New Haven Harbor zooplankton were holoplankters, 

 predominantly calanoid copepods (Figure 4-15) . In New Haven Harbor, the 

 dominant copepods were Acartia tonsa and Acartia hudsonica (= clausi) 



(Table 4-4) . Together, these two congeners comprised the majority of 

 the total zooplankton and as much as 93% of the calanoid copepod assem- 

 blage (Figure 4-14) (NAI , 1977; 1978). A. hudsonica normally exhibited 

 a major population bloom in the spring while A. tonsa populations peaked 

 in mid- to late summer; typically, when the density of one species was at 

 a peak level, the other was virtually absent (Figure 4-16) . Similar to 

 the pattern observed in New Haven Harbor, total zooplankton species 

 abundance peaks at Millstone Point coincided with A. tonsa and A. 

 hudsonica peaks (Figure 4-14b) . The successional pattern of A. hud- 

 sonica spring dominance/A. tonsa summer dominance was apparent at Mill- 

 stone (Figure 4-14b) . Conover (1956) and Jeffries (1962) were among the 

 first to describe this successional relationship which generally pre- 

 vails in most estuaries and embayments from Cape Cod to Cape Hatteras 



(Cronin et aJ . , 1962; Jeffries, 1964; Heinle, 1966; Sage and Herman, 

 1972) . 



(Text continued on page 4-38) 



