Thermal Tolerance in Tropical Versus Subtropical Pacific Reef Corals

Abstract

Upper lethal temperature tolerances of reef corals in Hawaii and at Enewetak, Marshall Islands, were determined in the field and under controlled laboratory conditions. Enewetak corals survived in situ temperatures of nearly 34° C, whereas 32° C was lethal to Hawaiian corals for similar short-term exposures. Laboratory determinations indicate that the upper thermal limits of Hawaiian corals are approximately 2° C less than congeners from the tropical Pacific. Differences in coral thermal tolerances correspond to differences in the ambient temperature patterns between geographic areas.