U-Th dating reveals regional-scale decline of branching Acropora corals on the Great Barrier Reef over the past century

Clark, Tara R., Roff, George, Zhao, Jian-xin, Feng, Yue-xing, Done, Terence J., McCook, Laurence J., and Pandolfi, John M. (2017) U-Th dating reveals regional-scale decline of branching Acropora corals on the Great Barrier Reef over the past century. Proceedings of the National Academy of Sciences of the United States of America, 114 (39). pp. 10350-10355.

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Hard coral cover on the Great Barrier Reef (GBR) is on a trajectory of decline. However, little is known about past coral mortality before the advent of long-term monitoring (circa 1980s). Using paleoecological analysis and high-precision uranium-thorium (U-Th) dating, we reveal an extensive loss of branching Acropora corals and changes in coral community structure in the Palm Islands region of the central GBR over the past century. In 2008, dead coral assemblages were dominated by large, branching Acropora and living coral assemblages by genera typically found in turbid inshore environments. The timing of Acropora mortality was found to be occasionally synchronous among reefs and frequently linked to discrete disturbance events, occurring in the 1920s to 1960s and again in the 1980s to 1990s. Surveys conducted in 2014 revealed low Acropora cover (<5%) across all sites, with very little evidence of change for up to 60 y at some sites. Collectively, our results suggest a loss of resilience of this formerly dominant key framework builder at a regional scale, with recovery severely lagging behind predictions. Our study implies that the management of these reefs may be predicated on a shifted baseline.

Item ID: 51314
Item Type: Article (Research - C1)
ISSN: 1091-6490
Keywords: U-Th dating, Acropora, coral, mortality, Great Barrier Reef
Funders: Marine and Tropical Science Research Facility (MTSRF), National Environmental Research Program Tropical Ecosystems Hub (NERP-TEH), Australian Research Council (ARC), Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies (CE), Australian Postgraduate Award, National Natural Sciences Foundation of China (NNSFC), Mia J. Tegner Fellowship
Projects and Grants: MTSRF Project 1.1.4, NERP-TEH Project 1.3, ARC LIEF project LE0989067, NNSFC grant 41472158
Date Deposited: 25 Oct 2017 07:30
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410402 Environmental assessment and monitoring @ 100%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 100%
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