85-2 Sat Jan 2 Symbiosis in the time of climate change: Bleaching of Exaiptasia pallida in response to concurrent warming and acidification Romanovich, LA*; Rade, RG; Fetcher, N; Voltzow, J; University of New England, Biddeford, ME; University of Scranton, PA; Wilkes University, Wilkes Barre, PA; University of Scranton, PA lromanovich@une.edu
Many cnidarians live in obligate symbiosis with photosynthetic dinoflagellates of the family Symbiodiniaceae. The introduction of environmental stressors associated with climate change, including ocean warming and ocean acidification, has an impact on this relationship and may initiate the bleaching response in which the host expels the symbionts. Using symbiotic Exaiptasia pallida as a model organism in which to study this association, we looked at the effects of projected future ocean conditions on the bleaching response. We designed a factorial experimental system in which anemones were placed in one of four treatments: (1) current ocean conditions at 28°C and pH 8.2; (2) future warming conditions at 33°C with current pH 8.2; (3) future acidification conditions at pH 7.8 with current temperature 28°C; and (4) future ocean conditions at 33°C and pH 7.8. We monitored the health of the symbiosis during exposure using fluorescence microscopy and chlorophyll fluorometry. We also assessed the final symbiont density in each anemone after 2 weeks in experimental conditions. Anemones exposed only to acidification did not lose symbionts and maintained a symbiosis equal to those maintained in the current oceanic conditions. Anemones in warmed waters and in the warmed plus acidified waters underwent bleaching to similar extents. We suggest that there is an interaction between the two factors’ effects on the rate of symbiont loss and change in chlorophyll fluorometry of in hospite symbionts. Thus it is important to evaluate the interactions of multiple stressors when trying to determine how organisms will respond to climate change.