Etiological Studies on Oyster Mortality. II. Polydora Websteri Hartmann—(Polychaeta: Spionidae)

Oysters from the major producing areas of Louisiana were found to be 100 per cent infected with the polychaete worm Polydora websteri. In Louisiana the population of Polydora was found to be highest in those areas remote from the sources of fresh water. In certain areas a positive correlation was found between the mortality of oysters and the degree of infestation by P. websteri, but this correlation was not substantiated by the results obtained from controlled laboratory experiments. It was concluded that the cause of mortality of oysters in Louisiana cannot be laid to Polydora per se, but that P. websteri as an abundant associated organism of the oyster community contributes a part toward the formation of a poor environment and in most cases is indicative of such an environment.