Reef coral survival and mortality at low temperatures in the Arabian Gulf : new species-specific lower temperature limits

A series of cold fronts passing over the western Arabian Gulf from December 1988 to March 1989 produced the longest period of sustained low water temperatures ever recorded in a coral reef area. Sea water temperatures recorded on two reefs during this period provide new estimates of lower thermal limits for reef coral survival. Severe mortality of the corals Acropora pharaonis and Platygyra daedalea occurred at the northern site where minimum temperatures fell below 11.5°C on four consecutive days and mean daily temperatures were 13°C or less for more than 30 days. However, Porites compressa, the principal reef-former in this area, and various faviid corals initially showed only sub-lethal effects and appeared normal after six months. Corals were not damaged at the southern site, where minimum water temperature fell below 12.5°C for two consecutive days, but mean temperatures were 14°C or less for only 5 non-consecutive days.