Sep 11, 2017

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

by
Tara R. Clark, George Roff, Jian-xin Zhao, Yue-xing Feng, Terence J. Done, Laurence J. McCook, John M. Pandolfi
,
Proceedings of the National Academy of Sciences
  • States that little is known about past Great Barrier Reef coral mortality before the advent of long-term monitoring (circa 1980s)
  • Uses paleoecological analysis and high-precision uranium-thorium (U-Th) dating to 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
  • States that in 2008, dead coral assemblages were dominated by large, branching Acropora and living coral assemblages by genera typically found in turbid inshore environments
  • Finds that the timing of Acropora mortality was occasionally synchronous among reefs and frequently linked to discrete disturbance events, occurring in the 1920s-60s and again in the 1980s-90s
  • Surveys conducted in 2014 revealed low Acropora cover (<5%) across all sites
  • Results suggest a loss of resilience of this formerly dominant key framework builder at a regional scale
  • Study implies that the management of these reefs may be predicated on a shifted baseline