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Abstract:
Rising seawater temperatures threaten corals and bleaching eventsare increasing in extent and frequency. In both 2014 and 2015 coralsin Hawai‘i had extensive bleaching in response to high seawatertemperatures. We tagged 40 pairs of coral colonies of two species,Montipora capitata and Porites compressa, and tracked their fate forthree years. Within each species the tagged corals were selected sothat one individual coral colony that bleached was adjacent to onecolony that retained its dark color. We collected 23 tissue samples ofeach coral colony over a three year time period that encompassed twoconsecutive bleaching events and the recovery period after bothbleaching events. Using amplicon sequencing we characterized theSymbiodinium community in each species of coral (ITS-2) and foundthat different coral species had different communities ofSymbiodinium. The microbiome also differed between the coralspecies and was also different between bleached and unbleachedcolonies (16S). Using qPCR we quantified the clade and abundanceof Symbiodinium in M. capitata over two years and found rapidrecovery of symbiont abundance after bleaching but little symbiontshuffling. Using ezRAD we did not detect loci that correlated tobleaching resistance but we did uncover hidden genetic diversitywithin P. compressa. Overall, there was less than 10% mortality inthe tagged coral colonies. By integrating analyses on the same coralcolonies we can study the factors that might contribute to how coralsresist and recover from thermal stress
