MICROBIAL SHELL DESTRUCTION IN DEEP-SEA MUSSELS, FLORIDA ESCARPMENT

Two distinctive pattens of microbial destruction of mineral shell in m ussels from the Florida Escarpment (3266 m water depth) are described. One pattern follows a surfacial selective removal of intercrystalline organic matrix creating caries-like pits. Pitting of the shell resemb les spreading bacterial colonies and results in substantial thinning o f the original shell. The second pattern consists of an extensive syst em of sacs with branched and tapered extensions penetrating deep into the shell. Both activities are carried out by unknown microbial agents on live mussels, as evidenced by the presence of repair nacre, which often underlies effected areas. Shell destruction is primarily biologi cal, providing conditions for enhanced chemical dissolution of the min eral shell.