Biennium horribile: very high mortality in the reef coral Acropora millepora on the Great Barrier Reef in 2009 and 2010

Tan, C.H, Pratchett, M.S., Bay, L.K., Graham, E.M., and Baird, A.H. (2018) Biennium horribile: very high mortality in the reef coral Acropora millepora on the Great Barrier Reef in 2009 and 2010. Marine Ecology Progress Series, 604. pp. 133-142.

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Coral cover has declined markedly in the recent past in many regions of the world, including the Great Barrier Reef (GBR), Australia. The major causes of this decline are generally considered to be mortality associated with large-scale severe disturbances (i.e. catastrophic mortality), such as Acanthaster planci outbreaks, cyclones and bleaching. However, background rates of mortality (i.e. not associated with catastrophic disturbance), are rarely quantified, but without these it is difficult to assess the relative importance of these 2 types of mortality (catastrophic and background). We quantified spatial and temporal variation in catastrophic and background whole-colony mortality of the common reef coral Acropora millepora over 24 mo at 2 sites in 3 regions separated by 700 km along the GBR. The study period included 2 cyclones and a flood. Overall mortality rates were exceptionally high. Of 180 colonies tagged in April 2009, only 36 (20%) were alive in April 2011, and 68% of this mortality occurred in intervals following the 3 large disturbances. Background mortality rates were also high in the Palm Islands, where they approached 40% yr-1 compared to <5% in the Whitsunday and Keppel Islands. These results support the hypothesis that catastrophic mortality has been the major cause of coral loss in recent years on the GBR and also suggest that background rates of mortality are increasing at some locations. Projected increases in the agents of catastrophic mortality, such as cyclones and bleaching, as a result of global warming are likely to threaten the persistence of many coral species.

Item ID: 55794
Item Type: Article (Research - C1)
ISSN: 1616-1599
Keywords: coral reefs; catastrophe; cyclone; disturbance; flood
Copyright Information: Copyright © Inter-Research 2018
Funders: Australian Research Council (ARC), Great Barrier Reef Marine Park Authority (GBRMPA), Australian Government, Australian Institute of Marine Science (AIMS)
Projects and Grants: ARC Centre of Excellence CE140100020
Date Deposited: 17 Oct 2018 22:51
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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