Investigating the Impact of Corallivorous Fishes on Bleached Corals

Abstract

Given the multitude of threats facing coral reefs, it is important that reef managers have a strong understanding of the impacts of various stressors on coral. One potential source of stress is injury caused by corallivorous fishes. While there is a body of literature demonstrating that these corallivores have few effects on healthy corals, some researchers have asked whether the same would be true for stressed corals. One factor that could exacerbate predation stress is coral bleaching. By helping managers comprehend how these stressors interact, they could then use estimates of corallivore populations as a metric to decide which reefs will better recover from a bleaching event. This study used predator exclusion cages to test the hypothesis that corallivores would impair corals recovering from bleaching. In order to compare the impacts of bleaching, corallivory, and caging on coral growth, 180 Porites compressa nubbins from five parent colonies, were evenly divided between six treatments cross-factoring bleaching state and cage type: (1) unbleached fragments under no cage, (2) unbleached fragments in partial cages, (3) unbleached fragments in full predator exclusion cages, (4) bleached fragments under no cage, (5) bleached fragments in partial cages, and (6) bleached fragments in full predator exclusion cages. This experiment did not detect an effect of corallivores on coral growth. Rather, this study demonstrated that corals were negatively impacted by caging artifacts.