title: Unprecedented mass bleaching and loss of coral across 12° of latitude in Western Australia in 2010-11.
abstract: BACKGROUND
  Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010-11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA).
  
  
  RESULTS
  Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%-83.9% of total coral cover, with the greatest losses in the Exmouth Gulf.
  
  
  CONCLUSIONS
  The anomalous thermal stress of 2010-11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast warming regimes may in part be mitigated by southern thermal refugia.
authors.affiliation: Marine Science Program, Department of Environment and Conservation, Kensington, Western Australia, Australia. james.moore@dec.wa.gov.au
authors.forename: James A Y
authors.initials: JA
authors.lastname: Moore
authors.forename: Lynda M
authors.initials: LM
authors.lastname: Bellchambers
authors.forename: Martial R
authors.initials: MR
authors.lastname: Depczynski
authors.forename: Richard D
authors.initials: RD
authors.lastname: Evans
authors.forename: Scott N
authors.initials: SN
authors.lastname: Evans
authors.forename: Stuart N
authors.initials: SN
authors.lastname: Field
authors.forename: Kim J
authors.initials: KJ
authors.lastname: Friedman
authors.forename: James P
authors.initials: JP
authors.lastname: Gilmour
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Holmes
authors.forename: Rachael
authors.initials: R
authors.lastname: Middlebrook
authors.forename: Ben T
authors.initials: BT
authors.lastname: Radford
authors.forename: Tyrone
authors.initials: T
authors.lastname: Ridgway
authors.forename: George
authors.initials: G
authors.lastname: Shedrawi
authors.forename: Heather
authors.initials: H
authors.lastname: Taylor
authors.forename: Damian P
authors.initials: DP
authors.lastname: Thomson
authors.forename: Shaun K
authors.initials: SK
authors.lastname: Wilson
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000254:growth & development*; D017753:Ecosystem; D018869:Heat-Shock Response; D006358:Hot Temperature / Q000009:adverse effects*; D012623:Seawater; D013312:Stress, Physiological / Q000502:physiology*; D013997:Time Factors; D014904:Western Australia