Meeting Abstract
Thermal stress from ocean warming destabilizes the nutritional symbiosis between corals and their intracellular dinoflagellate symbionts Symbiodinium spp., a response that results in an energy deficit for the coral host. Coral hosts with large energy reserves or those that compensate for the loss of energy by heterotrophic feeding may have a greater chance of surviving warming conditions. Recent research has focused on the response of adult corals to thermal stress, however, it is unclear how the post-settlement environmental or the nutritional condition of early life history stages shape their performance and survival under thermal stress. We evaluated the effects of conditioning regimes on the growth, survivorship, and thermal stress response of juvenile Pocillopora acuta corals. Larvae collected from parental colonies in Kāne‘ohe Bay, Hawai‘i were settled and exposed to cool (25.7°C) or ambient (27.3°C) temperature in filtered seawater (1μm) in the presence or absence of a heterotrophic food source. Juvenile colonies were exposed to these temperatures for one month and then exposed to a thermal stress test (max. temperature ca. 32°C). After one month, there was a positive effect of cool temperature on survivorship, and a positive effect of heterotrophic feeding on growth. During the thermal stress test, there was an interactive effect of temperature and heterotrophic feeding on juvenile performance, indicating that these conditions play complex roles in shaping physiological responses. These results suggest that cool seasonal periods and heterotrophic feeding enhance the resilience of corals to thermal stress events.
