remanent gametes, but none appeared to be associated with 

 disposal operations. 



The histopathological studies indicated that the retardation 

 of gonadal development, the absence of crystalline style and the 

 dysfunction of plycate organ could be associated with mussels at 

 all three populations transplanted in the western Sound. However, 

 these results should be considered only as presumptive and 

 interpreted with caution for the following reasons: 



1)- Field experimental results are by nature correlational, 

 therefore, no causation can be assumed. 



2) The results could also be correlated with other unknown 

 or uninvestigated factors, and 



3) The results of histopathological studies presented 

 herein were derived from mussels which survived 

 mortalities of undetermined causes; hence, they 

 represented the "fittest", particularly at the three 

 transplanted stations (WLISc, 500MW and WLISrN) where 

 the average cumulative mortality was more than 7 0%. 

 The results could be biased in favor of lesser spatial 

 association with the observed abnormalities. If all 

 the dead and dying mussels could have been recovered by 

 more frequent sampling during July, August and 

 September with subsequent examination of their tissues, 

 more definitive conclusions might be reached. 



The chances of recovering dead and dying mussels would be 

 improved in future projects by augmenting the initial deployment 

 with a monthly introduction of mussels at each station, followed 

 by sampling these introduced mussels at monthly intervals 

 concurrent with the sampling schedule of the mussels deployed 

 initially. This approach would achieve two objectives: the 

 monthly deployment should reveal more clearly the relationship 

 between uptake rates of trace metals and PCBs and associated 

 biological effects (mortalities, histopathology, W/D ratios, 

 etc.) and allow recovery of more morbid mussels, while the 

 initial deployment should represent cumulative effects. 

 Moreover, the indications suggested in this study should be 

 followed by vigorously controlled laboratory experiments in an 

 attempt to determine causations of the observed abnormalities. 



Conclusions 



This investigation suggested that the disposal of dredged 

 material has only a limited influence on the trace metal and PCB 

 concentrations of mussel populations deployed on _ or near the 

 disposal site in western Long Island Sound. Similar tissue 

 concentrations of Cd, Cu, and Zn were found in all three 



17 



