Virginia Institute of Marine Science
Journal of Shellfish Research
Oysters on natural beds in the upper seed area of the James River died anaerobically in the winter and early spring of 1979-80 during prolonged exposure to fresh water and low salinities (< 5 ppt). Heavy rains in .the fall of 1979 combined with the usual winter-spring runoff to produce low salinities. Oysters in trays were transplanted in late March and early April to six high-salinity areas where mortalities were found a month later. The oysters died slowly within closed shells because they were unable to feed and respire in the nearly fresh water. This produced a strong, malodorus stench and blackened shell margins that are characteristic of anaerobiotic decay. Similar phenomena occurred previously in the Rappahannock River about 1 May during several wet years during the past three decades. At depths of 5 to 6 m, dissolved oxygen was depleted and everything on the bottom became black with iron and other heavy metal sulfides. Dead oysters were not discovered until June after waters had become aerobic again.
Oysters -- Virginia
Andrews, J. D., Anaerobic mortalities of oysters in Virginia caused by low salinities (1982). Journal of Shellfish Research, 2(2), 127-132.