Interdependence between reef fishes and scleractinian corals

Scleractinian corals are the primary habitat-forming species in healthy, intact coral reef ecosystems. Removal or destruction of corals will therefore, profoundly alter the structure and dynamics of coral-reef habitats, with likely effects across a diverse range of reef fishes. Conversely, many reef fishes are considered fundamental to the structure and resilience of reef ecosystems, such that degradation of coral-dominated habitats may initiate a downward spiral in ecosystem state leading to fundamental shifts in structure and function. This paper explores strong interdependence between reef fishes and scleractinian corals, focusing on the data necessary to establish linked vulnerabilities of fish and coral given increasing incidence of major disturbances. A large and increasing number of studies purport to show strong coral dependence among reef fishes based on strong and positive correlations between local abundance and live coral cover. However, coral cover may explain a very limited portion of spatial structure in the abundance of fishes, even among those species known to depend on live coral (e.g., for food and habitat). This is because coral-dependent fishes may be highly specialized and only use a limited suite of available corals. Also, numerous factors (e.g., local recruitment) may contribute to variation in abundance of fishes among locations with established coral communities, and reliance on corals is really only apparent by documenting changes in the individual abundance and fitness of reef fishes following localized declines in coral cover. Likewise the role of fishes in enhancing coral reef resilience is most apparent during recovery from major disturbances, but it is unclear whether reef fishes (e.g., corallivores) increase or decrease susceptibility of corals to disease and bleaching. This review emphasizes the importance of long-term monitoring, combined with effective experimental studies to establish the linked vulnerabilities of fishes and corals to ongoing disturbances, as well as interdependence between fishes and corals in reef resilience