type of disease is involved. Although the etiology of the 

 disease has not been established, the data and observations 

 suggest that some environmental factor or combination of factors 

 predispose the crabs to this particularly aggressive form of 

 shell disease. 



The descriptions of shell disease in the blue crab 

 population in the Pamlico River are preliminary. It has been 

 established, however, that the disease is not unique to the 

 Pamlico River since crabs with shell disease have also been 

 collected in the Alligator River and southern Albemarle Sound. 

 Reports also have been made of similar types of disease in blue 

 crabs from the St. Johns River in Florida, and from Freeport, 

 Texas. These studies of blue crabs in North Carolina suggest 

 that there may be chemical as well as biological factors involved 

 in the development of shell disease in crustaceans (Fig. 7); 

 chemicals (or stress related to chemical contaminants) may have a 

 role in shell disease in some situations, even where chitin- 

 digesting bacteria have not been culturable from shell lesions. 

 This research area needs to be expanded, in both microbiological 

 studies and chemical analyses of tissues from diseased crabs. 



23 



