title: Thermal stress and coral cover as drivers of coral disease outbreaks.
abstract: Very little is known about how environmental changes such as increasing temperature affect disease dynamics in the ocean, especially at large spatial scales. We asked whether the frequency of warm temperature anomalies is positively related to the frequency of coral disease across 1,500 km of Australia's Great Barrier Reef. We used a new high-resolution satellite dataset of ocean temperature and 6 y of coral disease and coral cover data from annual surveys of 48 reefs to answer this question. We found a highly significant relationship between the frequencies of warm temperature anomalies and of white syndrome, an emergent disease, or potentially, a group of diseases, of Pacific reef-building corals. The effect of temperature was highly dependent on coral cover because white syndrome outbreaks followed warm years, but only on high (>50%) cover reefs, suggesting an important role of host density as a threshold for outbreaks. Our results indicate that the frequency of temperature anomalies, which is predicted to increase in most tropical oceans, can increase the susceptibility of corals to disease, leading to outbreaks where corals are abundant.
authors.affiliation: Department of Marine Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America. jbruno@unc.edu
authors.forename: John F
authors.initials: JF
authors.lastname: Bruno
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Selig
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Casey
authors.forename: Cathie A
authors.initials: CA
authors.lastname: Page
authors.forename: Bette L
authors.initials: BL
authors.lastname: Willis
authors.forename: C Drew
authors.initials: CD
authors.lastname: Harvell
authors.forename: Hugh
authors.initials: H
authors.lastname: Sweatman
authors.forename: Amy M
authors.initials: AM
authors.lastname: Melendy
mesh_terms: D000820:Animal Diseases / Q000453:epidemiology; D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D004196:Disease Outbreaks; D017753:Ecosystem; D017752:Greenhouse Effect; D006358:Hot Temperature; D010140:Pacific Ocean; D011793:Queensland