Resistance and resilience of a coral reef fish community to changes in coral cover

Abstract

Coral reefs are being degraded worldwide by perturbations that range from local disturbances to large-scale climate forcing. To gain insight into possible responses of the fish community to losses of live coral, we surveyed large plots that represented the range in cover of live coral in lagoons of Moorea, French Polynesia, to explore relationships between cover of live coral and 3 attributes of the associated fish community: species richness, total abundance, and species composition. All measured attributes of the fish community were insensitive to changes in live coral cover over a wide range before falling sharply as live coral cover approached zero. A field experiment in which the percentage of living tissue of branching coral was varied while total coral volume and structural complexity were kept constant revealed a rapidly asymptotic relationship of fish richness with increases in cover of live coral that was qualitatively identical to the pattern documented in our surveys. There was qualitative agreement in the pattern of abundance response of fish with variation in cover of live coral between the experiment and field surveys. While the structural heterogeneity provided by coral skeletons can influence the local fish assemblage, the experiment reported here demonstrates that the amount of living coral tissue alone can have a substantial effect on the structure of the fish assemblage. Taken together, the results suggest that local fish assemblages could be resistant to variation in abundance of live coral, changing significantly only as coral becomes rare, while recovery may occur with only modest increases in live coral. © Inter-Research 2008.