Nov 3, 2017

Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia

Morane Le Nohaïc, Claire L. Ross, Christopher E. Cornwall, Steeve Comeau, Ryan Lowe, Malcolm T. McCulloch, Verena Schoepf
Scientific Reports
  • States that in 2015/16, a marine heatwave associated with a record El Niño led to the third global mass bleaching event documented to date
  • States that this event impacted coral reefs around the world, including in Western Australia (WA), although WA reefs had largely escaped bleaching during previous strong El Niño years
  • Conducts coral health surveys during the austral summer of 2016 in four bioregions along the WA coast (~17 degrees of latitude), ranging from tropical to temperate locations
  • Finds that the heatwave primarily affected the macrotidal Kimberley region in northwest WA (~16°S), where 4.5–9.3 degree heating weeks (DHW) resulted in 56.6–80.6% bleaching
  • Findings demonstrate that even heat-tolerant corals from naturally extreme, thermally variable reef environments are threatened by heatwaves
  • Notes that the only other major mass bleaching in WA occurred during a strong La Niña event in 2010/11 and primarily affected reefs along the central-to-southern coast
  • Results suggest that WA reefs are now at risk of severe bleaching during both El Niño and La Niña years