The Growth of Oysters Parasitized by the Fungus Dermocystidium marinum and by the Trematode Bucephalus cuculus

Abstract

Growth of individual oysters was recorded monthly for 16 months in a field study by the authors and weekly for 6 months in a laboratory experiment by W. G. Hewatt in Louisiana. Study of sectioned tissues by J. G. Mackin showed that over half the oysters were infected by the fungus Dermocystidium marinum. Growth of infected oysters was adversely affected; heavily infected ones stopped growing or even lost in length and weight for several weeks or months, and finally died. One oyster infected by sporocysts of Bucephalus cuculus grew unusually fast at first, but slowly later. Uninfected oysters 8-24-months old grew at an almost constant rate at all seasons. Inclusion of parasitized individuals in a growth experiment may lead to erroneous conclusions unless effects of the parasites are analyzed.