Abstract

The decay of corals in the Lesser Antilles due to tissue necrosis is nowadays a worrying phenomenon, and their capacity of regeneration is a key determinant of coral reef resilience. To estimate the healing capacity of lesions in a common coral species of Caribbean reefs, artificial lesions (15 mm in diameter and 2-3 mm deep) were created on 12 colonies of Porites astreoides (15 to 20 cm in diameter) with a pneumatic drill. The 12 colonies located on a reef flat, within an area of 10 m, were monitored during five months. Pictures of the lesions were taken at 14 periods from day 0 to day 150. New polyps and coenenchyme rapidly colonized the edge of the lesions, but after some weeks the lesion healing slowed down: the barren coral skeleton was colonized by algal turf and Cyanobacteria that also trapped sediment. At the end of the experiment (150 days), none of the artificial lesions completely healed. Among the colonies, 6 of them presented some trace of healing (never above 28,5%) and 6 of them showed expansions of the lesion size (65,4 % maximum). The global result was an average increase of the lesions size of 15%. This experiment suggests that Porites astreoides presents a low healing capacity to recover from physical injury. This phenomenon seems to be linked to the high competitive capacity of turf algae and Cyanobacteria to colonize the barren coral skeleton, thus compromising the resilience of coral populations.

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