Disturbance, habitat structure and the ecology of fishes on coral reefs

This paper reviews empirical studies relating communities of coral-reef fishes to the characteristics of the underlying habitat, and the effects of habitat disturbance. Many contrasting patterns in the relationships between fish communities and coral cover, habitat heterogeneity or topographic complexity have been described, including strong effects of particular habitat characteristics (both positive and negative), as well as those finding weak or no relationships. In addition, a whole range of potential responses to different kinds of disturbance, including hurricane damage, crown-of-thorns (Acanthaster planci) outbreaks, and El Nino-associated coral and sea urchin die-offs, have been described. Few workers have attempted to test among alternative models about the importance of resource limitation or responses to disturbance, so critical hypotheses have not been tested. Potential generalizations may be obscured due to a number of problems faced when making comparisons among existing studies. These include the enormous variation in the magnitude of changes to habitats observed, restrictive assumptions about the form of relationships between fish and habitat variables, inadequate descriptions of habitat and fish community structure, a heavy reliance on 'natural', pseudoreplicated experiments and a plethora of different numerical and analytical techniques. We conclude that the search for generalizations would be facilitated by a greater attention to theory and clearer statements of the hypotheses being tested. Evaluation of the general importance of fish-habitat interactions must await the application of common observational and experimental methodologies to a wider range of fish taxa and locations.