The effects of ocean acidification on wound repair in the coral Porites spp.

Abstract

Scleractinian corals on tropical reefs are exposed to many natural and anthropogenic disturbances, and while much is known about their responses to such conditions, it is unclear whether the responses will remain the same in a future affected by climate change and ocean acidification. To evaluate how one aspect of these effects — wound repair — might be influenced by ocean acidification, small colonies of massive Porites spp. from the back reef of Moorea, French Polynesia, were damaged to simulate the effects of single bites by corallivorous fishes, and healing was measured under contrasting PCO2 regimes. Using experiments lasting 19–20d and employing superficial (2013) or deep (2014) lesions, the effects of damage were evaluated at ~400μatm (ambient) and ~1000μatm PCO2 (both at ~28.5°C) using calcification and healing as dependent variables. Damage reduced calcification of massive Porites spp. in 2013, but not in 2014, and PCO2 had no effect on area-normalized calcification or healing in both years, although biomass-normalized calcification was reduced by high PCO2 in 2014. Overall these results reveal the physiological resilience of this functional group of corals to the extent of ocean acidification expected by the end of this century, and suggest that over this period small colonies will remain capable of recovery from minor damage arising from fish corallivory.