Thresholds and the resilience of Caribbean coral reefs

Mumby, Peter J., Hastings, Alan and Edwards, Helen J. (2007) Thresholds and the resilience of Caribbean coral reefs. Nature, 450 7166: 98-101. doi:10.1038/nature06252

Author Mumby, Peter J.
Hastings, Alan
Edwards, Helen J.
Title Thresholds and the resilience of Caribbean coral reefs
Journal name Nature   Check publisher's open access policy
ISSN 0028-0836
Publication date 2007-11-01
Sub-type Article (original research)
DOI 10.1038/nature06252
Volume 450
Issue 7166
Start page 98
End page 101
Total pages 4
Place of publication London, United Kingdom
Publisher Nature Publishing Group
Language eng
Formatted abstract
The deteriorating health of the world's coral reefs threatens global biodiversity, ecosystem function, and the livelihoods of millions of people living in tropical coastal regions. Reefs in the Caribbean are among the most heavily affected, having experienced mass disease-induced mortality of the herbivorous urchin Diadema antillarum in 1983 and two framework-building species of coral. Declining reef health is characterized by increases in macroalgae. A critical question is whether the observed macroalgal bloom on Caribbean reefs is easily reversible. To answer this question, we must resolve whether algal-dominated reefs are an alternative stable state of the ecosystem or simply the readily reversible result of a phase change along a gradient of some environmental or ecological parameter. Here, using a fully parameterized simulation model in combination with a simple analytical model, we show that Caribbean reefs became susceptible to alternative stable states once the urchin mortality event of 1983 confined the majority of grazing to parrotfishes. We reveal dramatic hysteresis in a natural system and define critical thresholds of grazing and coral cover beyond which resilience is lost. Most grazing thresholds lie near the upper level observed for parrotfishes in nature, suggesting that reefs are highly sensitive to parrotfish exploitation. Ecosystem thresholds can be combined with stochastic models of disturbance to identify targets for the restoration of ecosystem processes. We illustrate this principle by estimating the relationship between current reef state (coral cover and grazing) and the probability that the reef will withstand moderate hurricane intensity for two decades without becoming entrained in a shift towards a stable macroalgal-dominated state. Such targets may help reef managers face the challenge of addressing global disturbance at local scales.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ
Additional Notes Published under Letters

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 305 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 330 times in Scopus Article | Citations
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Created: Tue, 23 Nov 2010, 14:40:20 EST