Elevated temperature impairs onset of symbiosis and reduces survivorship in larvae of the Hawaiian coral, Fungia scutaria

Many corals obtain their obligate intracellular dinoflagellate symbionts from the environment as larvae or juveniles. The process of symbiont acquisition remains largely unexplored, especially under stress. This study addressed both the ability of Fungia scutaria (Lamarck 1801) larvae to establish symbiosis with Symbiodinium sp. C1f while exposed to elevated temperature and the survivorship of aposymbiotic and newly symbiotic larvae under these conditions. Larvae were exposed to 27, 29, or 31 degrees C for 1 h prior to infection, throughout a 3-h infection period, and up to 72 h following infection. Exposure to elevated temperatures impaired the ability of coral larvae to establish symbiosis and reduced larval survivorship. At 31 degrees C, the presence of symbionts further reduced larval survivorship. As sea surface temperatures rise, coral larvae exposed to elevated temperatures during symbiosis onset will likely be negatively impacted, which in turn could affect the establishment of future generations of corals.