Bacterial Assemblages And Histopathology Of Shell Disease     Andrei Chistoserdov1, Roxanna Smolowitz2, Feliza Mirasol1, Andrea Hsu2.   1MSRC, SUNY at Stony Brook, Stony Brook, NY; 2Marine Biological Laboratory, Woods Hole, MA     Shell disease in free-living lobster populations along the coast from Eastern Long Island Sound (ELIS), NY, to the Vineyard Sound, MA, is characterized by erosions of variable depth on the dorsal carapace, often resulting in thin, easily compressed shells. Histopathologically, diffuse, deeply extensive erosions are common. Carapace matrix in the erosions is usually missing. But in some instances, unlike lesions noted in impoundment disease, pillars of carapace matrix remain in the pitted shell. The predominate organism found at the interface of necrotic and live shell are bacteria. A combination of culture-based and molecular techniques was used to study these bacterial consortia. Preliminary denaturing gradient gel electrophoresis (DGGE) data indicate that up to five independent phylotypes of bacteria are present in lobster lesions. At least two of them were found in all lobsters from ELIS. This is consistent with the five to six morphotypes of bacteria, which were cultured on a marine agar. All isolated bacteria were either aerobic or facultatively anaerobic. Two different types of fastidious chitinolytic bacteria were isolated on a medium containing chitin. No correlation has been found between the presence or severity of shell disease and the presence of bacteria in hemolymph.