Infection Experiments in Nature with Dermocystidium marinum in Chesapeake Bay

摘要: Dermocystidium marinum is a pathogen which kills oysters in Chesapeake Bay from July through October. The fungus proliferates readily only at temperatures above 25°C but overwinters as sub-clinical cases. Experiments were conducted Nature to demonstrate the effects of proximity infected on epizootiology isolated disease-free populations. Prevalence ofDermocystidium York River was moderate 1957, heavy 1959, and extremely low 1963. In with 40 feet isolation, groups mixed showed large increases deaths prevalences over controls. so widely prevalent during long hot summer that relatively minor reductions death rates obtained by 50 isolation. 1963, nearly absent, failure laboratory infection techniques caused late timing experiment, results inconclusive. A new disease “MSX”, protistan parasite, developed high 1963 lots. This organism, destroying oyster, populations high-salinity waters (above 15‰ summer) has effectively reducedDermocystidium role an oyster lower Bay. Losses fromDermocystidium are dependent upon duration warm seasons survival cases winter. MSX, slightly more sensitive salinities much tolerant thanDermocystidium. decline disappearance suggests may be solely transmission oyster.