Mortality and Condition of the American Oyster in Galveston Bay, Texas
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Mortality and condition of the American oyster, Crassostrea virginica , were studied on sixteen 0.1-hectare sites on reefs in the bay. Oyster mortality was evaluated by 3 methods--the box-count method (number of articulated empty shells/number of articulated empty shells plus live oysters), the catch-curve method (log frequency versus size), and by tray experiments in which open tray, closed tray, and predator-inclusion trays (in which an oyster drill, Thais haemostoma was enclosed in each) were used. A weight/volume condition index was positively correlated with a gonadal index. Glycogen concentration was negatively correlated with salinity whereas intensity of infection by Perkinsus marinus was positively correlated with salinity. High mortalities were apparently the result of frequent flooding at low salinity sites, but appeared to be caused by the oyster drill and disease (due to the protozoan P. marinus ) at high-salinity sites.