Coral responses in single- and mixed-species plots to nutrient disturbance

Abstract

Space is a limiting resource in coral reef communities causing actively growing coral colonies to come in proximity and interact with each other. Although most contact interactions among corals have been studied extensively, very few non-contact and non-aggressive interactions have been documented so far. We present results from a 3 yr field study of coral communities showing that, under unperturbed conditions, the reef-building coral Porites cylindrica exhibits significantly higher growth when transplanted together with 2 other species (P. rus and Pavona frondifera) than when grown in monoculture. However, the introduction of a chronic disturbance (nutrient enrichment) adversely affected its growth rates and survival, thus overturning the earlier trend. Furthermore, the 3 species used in the experiment exhibited different responses to the perturbation (negative, no effect, positive). Our results show that the presence of other species can enhance performance at the colony level, while differential species responses potentially provide buffering effects at the community level that may contribute to the maintenance of community structure and function during periods of disturbance.