Notes on Fungus Parasites of Bivalve Molluscs in Chesapeake Bay

My hobby is collecting the mollusks of Chesapeake Bay.. Having placed a few specimens in museums, and having made a check list · (no new species yet) with appended distribution records, I found my hobby less stimulating than rily research .. , But then my research had. taken a turn which opened up new and inviting fields of discovery. First came a devastating mortality of oysters in the Rappahannock River, for which no explanation has been found. Then Mackin et~ .. l. (\u27]_950) discovered the fungus disease of oysters, Dermocystidium marinum ... But not until Ray (1952) developed the thioglycollate culture technique for .easy detection of the fungus did we seriously begin to study oyster mortalities and their causes in Virginia (Hewatt and Andrews,. 1954) .. For some time Ray and Mackin searched among the invertebrate associates of oysters for alternate hosts, only to find that infection was easily accomplished directly from one oyster to another through water-borne spores (J. G. Mackin, Personal Communication). Since other bivalve mollusks would not be suspected as alternate hosts for an oyster disease, little effort was made ,to check them. With this background, we at the Virginia Fisheries Laboratory were surprised in August, 1953, to find the meat of a dead clam, Venus mercenaria, infected with a D. marinum-like fungus. During the fall and winter of 1953-54, 12 of-16 species of bivalve mollusks collected near Gloucester Point, Virginia, were found infected with similar fungi (Table I). None of the fungus parasites has been identified except the one causing a mycosis in oysters. How many species of fungi are involved? Can spores from one host species infect individuals of other species? And of most immediate importance, how many bivalve species will serve as host to the oyster parasite