Ocean Sci. Discuss., 9, 1691-1703, 2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Ocean Science (OS). Please refer to the corresponding final paper in OS.
The 2011 marine heat wave off southwest Australia
T. H. Rose1, D. A. Smale2, and G. Botting1
1Cockburn Sound Management Council, Department of Environment and Conservation, P.O. Box 5161, Rockingham Beach, WA 6969, Australia
2School of Plant Biology and UWA Oceans Institute, University of Western Australia, Crawley 6009, WA, Australia

Abstract. Over 2000 km of Western Australian coastline experienced a significant marine heat wave in February and March 2011. Seawater temperature anomalies of +2–4 °C were recorded at a number of locations and satellite-derived SSTs were the highest on record. Here, we present seawater temperatures from southwestern Australia and describe, in detail, the marine climatology of Cockburn Sound; a large, multiple-use coastal embayment. We compared temperature and dissolved oxygen levels in 2011 with data from routine monitoring conducted from 2002–2010. A significant warming event, 2–4 °C in magnitude, persisted for >8 weeks, and seawater temperatures at 10 to 20 m depth were significantly higher than those recorded in the previous 9 yr. Dissolved oxygen levels were depressed at most monitoring sites, being ~2 mg l−1 lower than usual in early March 2011. Ecological responses to short-term extreme events are poorly understood, but evidence from elsewhere along the Western Australian coastline suggests that the heat wave was associated with high rates of coral bleaching, fish, invertebrate and macroalgae mortalities, and algal blooms. However, more ecological information from Cockburn Sound and other multiple-use embayments is urgently needed. The 2011 heat wave provided insights into conditions that may become more prevalent in Cockburn Sound, and elsewhere, if the intensity and frequency of short-term extreme events increases as predicted.

Citation: Rose, T. H., Smale, D. A., and Botting, G.: The 2011 marine heat wave off southwest Australia, Ocean Sci. Discuss., 9, 1691-1703, doi:10.5194/osd-9-1691-2012, 2012.
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