Shell disease, therefore, is found in crustaceans of many 

 species, including those discussed in this section. The disease 

 occurs along the entire Atlantic coast of United States, as well 

 as in many other geographic locations — inshore and offshore, 

 polluted and non-polluted. It appears in a variety of forms, 

 including surface pitting, blackening of the shell, and areas of 

 shell perforation which may be extensive. 



3.0 RELATIONSHIP OF SHELL DISEASE TO POLLUTION 



Most of the visible signs of shell disease in crustaceans, 

 and the variety of microorganisms isolated from lesions, were 

 reported long before environmental pollution was considered as a 

 possible predisposing factor. Much has been learned during the 

 last two decades, however, as a result of extensive studies in 

 contaminated waters of both the east and west coasts of the 

 United States. Most studies, however, have dealt with surveys on 

 visible signs of disease, the geographical distribution of 

 disease, and pathological conditions noted in tissues and organs. 

 Very few observations have been made on different year classes, 

 temporal and spatial effects, and seasonal influences related to 

 differences in animal behavior, feeding habits, and population 

 density. 



Observations on lobsters sampled on the Massachusetts coast 

 (Estrella, 1984), showed a higher prevalence of shell disease in 

 specimens taken from polluted sites (Boston Harbor and Buzzards 

 Bay) than in those taken from open and deeper stations near Cape 

 Ann, Cape Cod Bay, and outer Cape Cod. Studies with rock crabs 

 (Sawyer et al, 1984) conducted on a multi-year basis, and taking 

 size and molting stage into account, also suggested that the 

 prevalence of shell disease is higher in stressed environments 

 than in those further from known sources of pollution. It is 

 important to note, however, that sewage sludge dumpsites are 

 rarely fished intensively, and therefore might be expected to 

 have more larger and older animals which molt infrequently, and 

 hence, may have higher prevalences of shell disease. It is also 

 important to keep in mind that temperature effects, seasons, molt 

 stages, and differing migratory patterns have profound effects on 

 prevalences of gill blackening and shell condition (Sawyer, 1982; 

 Sawyer et al, 1985) . 



Studies that support an association of pollution and shell 

 disease have been published, and gross effects documented. 

 Statistical analyses have shown that the types of shell lesions 

 of concern occur naturally, but are numerically more frequent and 

 severe in specimens collected from polluted waters. Gopalan and 

 Young (1973) examined "shell disease" in the caridean shrimp, 

 Crangon septemspinosa , an estuarine and coastal food chain 

 organism extremely important in the diet of bluefish, weakfish, 

 flounders, sea bass, and other commercial and recreational 

 species. Samples of shrimp from the New York Bight apex showed 

 that up to 15% of them had eroded appendages and blackened 

 erosions of the exoskeleton. Similar signs of disease were only 



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