| Summary: | Due to increased greenhouse gas emissions, Earth's climate, including that of its oceans, has changed considerably since the industrial revolution. Two effects of climate change are ocean warming and ocean acidification. Ocean warming is caused by the entrapment of infrared radiation due to increased atmospheric CO2. Ocean acidification is the process by which CO2 goes into solution with seawater, thus decreasing the pH. One of the detrimental effects of ocean warming and ocean acidification is the process of bleaching in corals and related cnidarians. Some sea anemones and corals form symbiotic relationships with photosynthetic dinoflagellates of the family Symbiodiniaceae. The dinoflagellates are able to photosynthesize and transfer metabolites to their hosts. Under certain conditions, including elevated sea water temperatures, corals lose their symbiotic dinoflagellates in a process called bleaching. Some corals and anemones turn white or bleach when the symbiosis is lost. Because ocean warming and ocean acidification are simultaneously occurring throughout the world's oceans, I exposed symbiotic anemones, Exaiptasia pallida, formerly known as Aiptasia, to different environments and examined the density of symbiotic dinoflagellates. I placed subjects into a heated treatment, an acidified treatment, and a combined treatment with both heated and acidified water. I assessed the density of dinoflagellates during a two-week bleaching period using chlorophyll fluorometry. I determined the density of dinoflagellates per ?g of protein after the bleaching period using a formulated symbiont assay protocol. Acidification alone did not induce bleaching. The combined treatment resulted in a reduction in dinoflagellate density that was not as steep as that in the heated treatments. This trend, however, was not observed in all trials. There appears to be a complex interaction between ocean warming and ocean acidification that affects the rate at which bleaching occurs in this symbiotic relationship. By understanding the ...
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