Lesion regeneration capacities in populations of the massive coral porites lutea at réunion island: Environmental correlates

Abstract

The capacity of corals for repairing partial mortality is a fundamental determinant of reef resilience. This capacity was assessed in the major reef-building coral Porites lutea by monitoring the regeneration of artificially induced lesions of standard size (330 ± 50 mm2, 3 mm deep) in 4 shallow reef flat populations at Réunion Island, under different environmental conditions related to sites and seasons, during a period without positive temperature anomalies. An exponential decay model with an asymptote described the lesion regeneration through 14 experiments. In spite of fast initial lesion regeneration, limited capacity for repair in this massive coral was indicated, as only 18% of the inflicted lesions healed completely within 6 to 9 mo. Lesion regeneration was fastest and most complete in the cooling and cool seasons, and may be impaired during the warming and hot seasons. Both solar radiation and seawater temperature contributed to seasonal changes in regeneration capacity, although they had opposite effects. While high radiation during the warming season decreased lesion regeneration rate, potentially through reduction of the photosynthetic efficiency of zooxanthellae, high temperature boosted it but also increased the amount of lesion area that could not be regenerated. Study sites were characterised by different temperature and radiation regimes, but these parameters alone could not explain all site effects on lesion regeneration capacity. Additional factors, most probably chronic stress caused by inputs of organic matter and run-off from land, may further compromise the regeneration capacity of corals and the resilience of coral populations. © Inter-Research 2011.