Meeting Abstract
Thermal stress driven by anthropogenic CO2 emissions can cause often lethal thermal stress to organisms in marine environments. Determining effects of thermal stress in tropical reef organisms is vital because coral reefs represent the most biodiverse and economically valuable marine ecosystems. Corkscrew sea anemones Bartholomea annulata form complex symbiotic relationships on Caribbean reefs, creating mutualistic cleaning networks that enhance reef fish diversity. We examined effects of thermal stress on host polyp growth and respiration, and on the abundance and photosynthetic rate of endosymbiotic microalgae in corkscrew anemones. Our results indicate that elevated seawater temperature (32°C) causes a significant decline in both host anemone body size and microalgal abundance within the host (bleaching), but an increase in chlorophyll concentration in the remaining microalgal cells. Anemones grow maximally at optimal coral reef temperatures of ~22-25°C, but relatively low temperature (18°C) also decreases anemone body size and microalgal abundance. The physiological mechanisms underlying these changes may involve a complex interplay between metabolic processes, in that temperature extremes significantly reduce photosynthetic rate whereas temperature increases significantly enhance respiration rate. These data have important implications for understanding physiological processes under stress in non-calcifying cnidarians, for application to coral reef conservation management under future climate change scenarios.
