HIGH TOLERANCE OF THE PACIFIC OYSTER (CRASSOSTREA GIGAS, THUNBERG) TO LOW TEMPERATURES

As an intertidal species, the Pacific oyster (Crassostrea gigas, Thunberg) is very tolerant to varying abiotic conditions. The temperature range for survival has, however, not been fully evaluated. Most notably, information about cold tolerance of the species is missing. As a first step toward acquiring a better understanding of the species' cold tolerance, the aim of this study was to measure mortality of groups of Pacific oysters after exposure to simulated winter conditions (-22 degrees C) for 24, 48, and 72 h. Such conditions are not very different from what can be experienced in nature during wintertime in Scandinavia. The Pacific oyster was found to be very tolerant to low temperatures with, in general, 50% survival after 24 h. Thermal acclimatization and premature adjustment to winter conditions allowing for improved survival after cold treatment were also observed.