ABSTRACT
Abstract Global climate change is having devastating effects on habitat structure in coralreef ecosystems owing to extreme environmental sensitivities and consequent bleaching of reefbuilding scleractinian corals. Coral bleaching frequently causes immediate loss of live coral and may lead to longer-term declines in topographic complexity. This review identies coral cover and topographic complexity as critical and distinct components of coral-reef habitats that shape communities of coral-reef shes. Coral loss has the greatest and most immediate effect on shes that depend on live corals for food or shelter, and many such shes may face considerable risk of extinction with increasing frequency and severity of bleaching. Coral loss may also have longer-term consequences for shes that require live corals at settlement, which are compounded by devastating effects of declining topographic complexity. Topographic complexity moderates major biotic factors, such as predation and competition, contributing to the high diversity of shes on coral reefs. Many coral-reef shes that do not depend on live coral are nonetheless dependent on the topographic complexity provided by healthy coral growth. Ecological and economic consequences of declining topographic complexity are likely to be substantial compared with selective effects of coral loss but both coral cover and topographic complexity must be recognised as a critical component of habitat structure and managed accordingly. Urgent action on the fundamental causes of climate change and appropriate management of critical elements of habitat structure (coral cover and topographic complexity) are key to ensuring long-term persistence of coral-reef shes.
