Decadal-scale rates of reef erosion following El Niño-related mass coral mortality

Roff, George, Zhao, Jian-xin and Mumby, Peter J. (2015) Decadal-scale rates of reef erosion following El Niño-related mass coral mortality. Global Change Biology, 21 12: 4415-4424. doi:10.1111/gcb.13006

Author Roff, George
Zhao, Jian-xin
Mumby, Peter J.
Title Decadal-scale rates of reef erosion following El Niño-related mass coral mortality
Journal name Global Change Biology   Check publisher's open access policy
ISSN 1365-2486
Publication date 2015-12-01
Sub-type Article (original research)
DOI 10.1111/gcb.13006
Open Access Status Not Open Access
Volume 21
Issue 12
Start page 4415
End page 4424
Total pages 10
Place of publication Chichester, United Kingdom
Publisher Wiley-Blackwell Publishing
Collection year 2016
Language eng
Formatted abstract
As the frequency and intensity of coral mortality events increase under climate change, understanding how declines in coral cover may affect the bioerosion of reef frameworks is of increasing importance. Here, we explore decadal-scale rates of bioerosion of the framework building coral Orbicella annularis by grazing parrotfish following the 1997/1998 El Niño-related mass mortality event at Long Cay, Belize. Using high-precision U-Th dating and CT scan analysis, we quantified in situ rates of external bioerosion over a 13-year period (1998–2011). Based upon the error-weighted average U-Th age of dead O. annularis skeletons, we estimate the average external bioerosion between 1998 and 2011 as 0.92 ± 0.55 cm depth. Empirical observations of herbivore foraging, and a nonlinear numerical response of parrotfish to an increase in food availability, were used to create a model of external bioerosion at Long Cay. Model estimates of external bioerosion were in close agreement with U-Th estimates (0.85 ± 0.09 cm). The model was then used to quantify how rates of external bioerosion changed across a gradient of coral mortality (i.e., from few corals experiencing mortality following coral bleaching to complete mortality). Our results indicate that external bioerosion is remarkably robust to declines in coral cover, with no significant relationship predicted between the rate of external bioerosion and the proportion of O. annularis that died in the 1998 bleaching event. The outcome was robust because the reduction in grazing intensity that follows coral mortality was compensated for by a positive numerical response of parrotfish to an increase in food availability. Our model estimates further indicate that for an O. annularis-dominated reef to maintain a positive state of reef accretion, a necessity for sustained ecosystem function, live cover of O. annularis must not drop below a ~5–10% threshold of cover.
Keyword Bioerosion
Coral bleaching
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
Official 2016 Collection
School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 3 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 3 times in Scopus Article | Citations
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