Epidermal lesions and mortality caused by vibriosis in deep-sea Bahamian echinoids: a laboratory study

When significant mortality of the bathyal spatangoid echinoid Paleopneustes cristatus occurred under laboratory conditions, we investigated the cause and course of the disease by culturing and identifying internal pathogens, then experimentally infecting healthy urchins with isolates of the suspecte d disease organism. The pathogen was determined to be the Gram-negative hal ophilic bacterium Vibrio alginolyticus. This species was also recovered fro m frozen post-challenge specimens of P. cristatus and from moribund individ uals of Archaeopneustes hystrix, another spatangoid reared under similar in vitro conditions. This is the first experimental study of bacterial diseas e in any deep-sea invertebrate.