Effects of High Temperature on Survival of the Giant Scallop

Abstract

Upper lethal temperatures of scallops are raised 1 °C. by each increase of 5 °C. in acclimation temperature. Acclimation upwards is fairly rapid (average 1.7 °C. per day over part of the range). Loss of acclimation to high temperature is slow, and appears to take as long as 3 months. There is a winter-to-summer decline in lethal temperature. It appears that naturally occurring water temperatures over 23.5 °C. will be lethal to scallops and directly responsible for mortalities. Temperatures over 21 °C. may also be a direct cause of mortalities but only in special circumstances could mortalities occur as a direct result of temperatures below this. In the "sub-lethal" temperature range, sudden temperature changes upward or downward may so reduce scallop mobility as to make them easier prey to enemies. In this way sudden temperature change could be an indirect cause of increased mortality.