Sublethal effects of PCBs have also bee.n described for many species. In the studies 

 on Palaemonetes pugio. Roesijadi et al. ( 1976) observed sublethal effects in concen- 

 trations of less than 100 ppb. Neff and Giam( 1977) found that lower concentrations 

 of Aroclor® and Halowax® reduced the intermolt periods of the horseshoe crab, 

 while Roesijadi etal.( 1976) demonstrated that Aroclor® 1254 significantly extended 

 the duration of development of the shrimp Palaemonetes pugio. In describing the 

 relationship between pollutants and natural diseases Couch and Courtney (1977) 

 found that 1 to 3 /ng 1 Aroclor® 1254 administered for 30 days increased the spread 

 and prevalence of Baculovirus. Mortality in the stress population was higher than in 

 the control population, and the incidence of viral infection in theexperimental popu- 

 lation of shrimp was approximately 50 percent higher than in the control series with- 

 out Aroclor® 1254. 



Neff and Giam (1977) conducted studies to compare the effects of Aroclor® 1016 

 and the PCN Halowax®1099 on juvenile horseshoe crabs, Limulus polyphemus. 

 The concentrations of these compounds, while in the low ppb range, were consider- 

 ably higher than one would expect to find in most estuarine environments. 



The anticipated effects of "hazardous wastes" constitute a major challenge. 

 Numerous documents attest to the increase in production of hazardous wastes with- 

 in the United States through the year 2000. Several recent incidents involving con- 

 tamination of drinking water, residences, and the environment as a whole have 

 dramatically focused on the hazards of these compounds to human health. Fre- 

 quently the compounds are unidentified and assembled in what might be best de- 

 scribed as a "potpourri." Although the Environmental Protection Agency is 

 presently conducting studies to devise means to identify these hazardous wastes, 

 there is virtually no way to assess the impact from runoff of these compounds into 

 adjacent estuarine waters. 



THE CHALLENGES OF THE EIGHTIES 



Although research during the seventies has contributed to a general understanding 

 of the effects of some organic compounds on estuarine and marine organisms, many 

 questions about the long-term impacts of these compounds are unanswered. Little 

 information is available on the rates at which many of these compounds deteriorate 

 within estuarine waters and sediments, although comparable information on rates of 

 deterioration in freshwater and soil isavailable. The results of one study(Christiansen 

 and Costlow, 1980) show that Dimilin® breaks down relatively slowly in brackish 

 water. Under laboratory conditions, 10 ppb Dimilin®, added to sea water, degraded 

 for 8 weeks before it had reached a level that did not affect survival of the larvae of 

 the mud crab Rhithropanopeus harrisii. 



Although the breakdown products of specific organic compounds have been iden- 

 tified, virtually nothing is known of the level at which these compounds are toxic in 

 estuarine systems, the extent to which they persist, or the amounts that may be 

 accumulated by marine organisms and passed on through the various trophic levels. 



Research in the seventies concentrated on the effects of individual compounds on 

 relatively small numbers of estuarine species. Although toxicity of individual pollu- 

 tants to marine organisms is modified by synergistic factors including salinity and 

 temperature, little research has been directed to a thorough understanding of these 

 interactions. The mortality of shrimp exposed to Aroclor® 1254 increased as salinity 

 increased over an 8-hour period. In contrast, mortality did not increase when shrimp 

 were maintained in conditions where only the salinity was increased or where only 

 PCB was present(Nimmoand Bahner, 1974). In studies on the effects of twojuvenile 

 hormone mimics (Altosid® and Altozar®) on larval development of mud crabs, a 

 variety of cyclic temperatures were used to indicate that the toxic effect of these two 

 compounds is reinforced by temperature (Christiansen et al., 1977). 



Considering the extent to which estuarine and coastal waters contribute runoff 

 containing many organic compounds, it is unfortunate that most studies to date have 



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