4-76 



As evidenced by chlorophyll a values (Figure 4-3) , phyto- 

 plankton blooms have progressively increased in magnitude during the 

 post-operational years (1975 through 1977) . Accompanying such changes 

 has been an increase in the intensity of late-winter/early spring blooms 

 of Skeletonema costatum. Non-toxic dinof lagellate blooms have occurred 

 during both preoperational (e.g. , June 1974) and post-operational (e.g. , 

 June 1976) periods; in addition, Conover (1956) alluded to red-tide con- 

 ditions in New Haven Harbor during the early 1950 's. There has been no 

 evidence of causal relationships between Harbor Station operations and 

 changes in phytoplankton population parameters . 



A comparison of monthly mean densities (stations, depths and 



tides averaged) for July 1973-October 1977 is presented for pre- versus 



post-operational comparisons of nine selected zooplankton taxa in Fig- 



* 

 ures 4-28 to 4-30 . Table 4-16 summarizes the differences observed in 



zooplankton assemblages by evaluating whether or not operational data 



(as converted to CB equivalences) fell within the ranges established by 



preoperational monitoring. For most taxa, operational estimates fell 



within or exceeded these ranges during at least 10 months (Table 4-16) . 



The general category of copepod copepodites were consistently less 



abundant in the operational period, probably due to the fact that many 



were classified as Acartia copepodites during this period (Figures 4-28, 



4-29 and 4-30) . All other species showing reduced abundance since 



operation commenced did so in months of peak abundances. Our conclusion 



regarding the CB data was that this method overestimated density during 



peak abundance periods. This interpretation of the comparability study 



results (Appendix 4-1) implies that high estimates of preoperational 



zooplankton densities were erroneous , that post-operational data are 



accurate, and that there is no evidence to indicate any adverse impact 



of Harbor Station activities on zooplankton populations. Operational 



* 



Data from samples taken by the 1/2 m net were adjusted to CB equivalences 



by application of the regression equations defined in the comparability 

 study. While these equations did not describe the data well, they pro- 

 vide the best available method to approximate comparability between 

 methods . 



(Text continued on page 4-81) 



