Variable effects of local management on coral defenses against a thermally regulated bleaching pathogen.

Abstract

Bleaching and disease are decimating coral reefs especially when warming promotes bleaching pathogens, such as <i>Vibrio coralliilyticus.</i> We demonstrate that sterilized washes from three common corals suppress <i>V. coralliilyticus</i> but that this defense is compromised when assays are run at higher temperatures. For a coral within the ecologically critical genus <i>Acropora</i>, inhibition was 75 to 154% greater among colonies from coral-dominated marine protected areas versus adjacent fished areas that were macroalgae-dominated. <i>Acropora</i> microbiomes were more variable within fished areas, suggesting that reef degradation may also perturb coral microbial communities. Defenses of a robust poritid coral and a weedy pocilloporid coral were not affected by reef degradation, and microbiomes were unaltered for these species. For some ecologically critical, but bleaching-susceptible, corals such as <i>Acropora</i>, local management to improve reef state may bolster coral resistance to global change, such as bacteria-induced coral bleaching during warming events.