Coral Reefs: A Reef Resilience Toolkit Module

Impacts

Coral disease outbreaks can lead to an overall reduction in live coral cover and reduced colony density. In extreme cases, disease outbreaks can initiate community phase-shifts from coral- to algal-dominated communities.

Coral diseases can also result in a restructuring of coral populations,1 for example a shift from long-lived slow growing massive reef builders to communities dominated by smaller, shorter-lived corals.2 In addition to the loss of coral tissue, disease can cause significant changes in reproduction rates, growth rates, community structure, species diversity, and abundance of reef-associated organisms.

Common coral diseases in the Caribbean. (A) Diploria strigosa with black band disease, (B) Dichocoenia stockesii with white plague, (C) Acropora cervicornis with white band and (D) Montastraea faveolata with yellow blotch syndrome. Photos E. Weil, from NOAA’s Center for Coastal Monitoring and Assessment

Global Patterns

The Caribbean has been referred to as a “hot spot” for disease because of a rapid emergence of new, extremely virulent diseases, increased frequency of events, and rapid spread of emerging diseases among new species and regions. At least 82 percent of coral species in the Caribbean are host to at least one disease.3

A number of studies indicate that disease prevalence in the Indo-Pacific region, American Samoa4 and Hawai‘i5 is currently quite low. However, reports of disease from new regions that were previously presumed to be unaffected (e.g., Solitary Islands, Australia), a higher percentage of reefs with disease, and recent increases in disease incidence in certain locations, indicate that across the region diseases appear to be exhibiting a rapid expansion in range and in types of disease since 2000.6 As efforts increase to document coral diseases from more locations within the Pacific, the lists of species affected by disease, locations where diseases are reported, and prevalence of those diseases, are steadily increasing.