5th Asia-Pacific Coral Reef Symposium
Date:
Title of talk: Lack of correlation between Symbiodiniaceae community composition and heat tolerance in acroporid corals from a Philippine reef
Abstract: Coral reefs worldwide are threatened by rapid warming of the oceans, yet many corals persist in the face of thermal stress. Coral heat tolerance is determined by many factors, such as the thermal history of the host and by associated Symbiodiniaceae, dinoflagellates that form a symbiotic relationship with corals. For many reefs in the Philippines, it remains to be determined whether corals from the same general reef area with similar thermal history, exhibit different levels of heat tolerance and whether these differences can be correlated with their associated symbiont communities. To elucidate the mechanisms underlying thermal tolerance of coral holobionts, we subjected approximately 30 colonies of Acropora digitifera, A. millepora and A. tenuis corals to 33°C (high temperature) versus 29°C (control) for about a week. Our results revealed inter-individual differences in heat tolerance in all three coral species, with 70% of A. digitifera, 50% of A. millepora, and 30% of A. tenuis colonies showing high tolerance to elevated temperature (i.e. no bleaching). Initial analyses using ITS2 sequencing and Symportal showed no clear correlation between observed inter-individual differences in heat tolerance and Symbiodiniaceae community profiles. This study provides further information to help identify corals and symbionts that are resilient to ocean warming, as an important first step in establishing thermotolerant coral stocks that can be used for breeding and conservation purposes.