Herbivory and the Resilience of Caribbean Coral Reefs: Knowledge Gaps and Implications for Management

Herbivory is a key process on coral reefs that can facilitate reef-building corals by excluding algae that otherwise negatively impact coral settlement, growth, and survivorship. Over the last several de cades, coral cover on Caribbean reefs has declined precipitously. On many reefs, large structurally complex corals have been replaced by algae and other non-reef-building or- ganisms, resulting in the collapse of physical structure and the loss of critical ecosystem services. The drivers of coral decline on Caribbean reefs are complex and vary among locations. On many reefs, populations of key her- bivores have been greatly reduced by disease and over- fishing, and this has resulted in the proliferation of algae that hinder coral recovery following major disturbances. Yet, evidence that increases in herbivory can promote coral recovery on Caribbean reefs has been mixed. Here, we discuss key contingencies that will modify the rela- tionships between herbivores, algae, and corals and identify critical knowledge gaps that limit our ability to predict when and where herbivores are most likely to facili tate coral persistence and recovery. Impacts of her- bivores on coral reef ecosystems will vary greatly in space and time and will depend on herbivore diversity and species identity. While there are still a large number of knowledge gaps, we make several management rec- ommendations based on our current understanding of the processes that structure reef ecosystems. Reversing the fate of Caribbean coral reefs will require the de - velopment of integrated management strategies that simultaneously address multiple stressors in addition to the impacts of fisheries on herbivore assemblages.