Differential and slow life-history responses of fishes to coral reef closures

Abstract

Life-history strategies are expected to underlie key ecological responses to disturbances and are becoming increasingly important in evaluations of the increasing frequency and magnitude of anthropogenic and climate stressors. Here, we evaluate changes in life histories of coral reef fishes after fishing disturbance, including feeding (mean trophic level), growth, reproduction, and mortality characteristics using a 42 yr fish biomass chronosequence created by Kenya's fisheries closures. As expected, the longer the closure, or time since fishing disturbance, the greater the mean age and body size metrics, and the lower the growth rate and mortality metrics. Unexpectedly, a linear decline in the mean trophic level of the fish community with the age of fisheries closure was found and was attributable to relatively slow recovery of the abundant herbivores. Trophic level and other life-history metrics were not significantly correlated with one another, and the life histories of herbivorous fishes (e.g. Acanthuridae, Scaridae) produced these weak relationships. None of the life-history metrics displayed clear leveling after 42 yr of closure, which corroborates other findings that indicate that the closures do not represent undisturbed or pristine ecosystems. Growth, reproduction, and mortality parameters are most influenced by the cessation of fishing, and these metrics indicate that herbivorous fishes can be slow to fully recover, necessitating appropriate restrictions to insure their populations and associated ecological functions are maintained. © Inter-Research 2012.