Summary: | Some corals and sea anemones form obligate symbiotic relationships with photosynthetic dinoflagellates of the genus Symbiodinium. Ocean warming and ocean acidification related to anthropogenic climate change have the potential to alter this relationship and contribute to bleaching events in which the symbionts are expelled from their hosts. Using the symbiotic anemone Exaiptasia pallida, I examined the effects of projected future climate conditions on this relationship. I exposed symbiotic anemones to one of three treatments: warmed waters, waters acidified by the addition of carbon dioxide, or warmed and acidified waters. I monitored symbiont loss using a combination of chlorophyll fluorometry and fluorescence microscopy. In addition to observed variation in bleaching response between anemones in the heated and in the combined heated and acidified treatments, there was also variation across trials. Anemones in the acidified treatment did not exhibit any signs of bleaching. These results suggest that there is a complex interaction between the effects of ocean warming and ocean acidification on this symbiotic relationship.
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