Growth and mortality of two groups of oysters, Crassostrea virginica (Gmelin), subjected to water from a steam-electric generating station.

Growth and mortality of oysters with high and low levels of Labyrinthomyxa marina (L) infection were measured during 1972 in (1) 0.1 ha ponds receiving a continuous flow of heated water from an electric power plant, (2) the power plant intake canal, and (3) the power plant discharge canal. Pond oysters had less accumulative mortality than intake or discharge canal oysters, regardless of Labyrinthomyxa infection. Only pond oysters (high-L and low-L) gains in biomass (increasing 171 and 5,953 g or 2 and 25%, respectively) by the end of the study. In the intake canal low-L oysters decreasing 6,293 g (27%) in the 10-month period prior to their loss while high-L oysters decreased 6,633 g (64%) by the end of the study. Oysters placed in the discharge canal during warm weather died within six weeks. Oysters held in the ponds grew as well or better than oysters from a natural reef in Galveston Bay.