Home > The 'marine heat wave' off Western Australia during the summer of 2010/11

The 'marine heat wave' off Western Australia during the summer of 2010/11

Posted on 11 November 2011

TitleThe 'marine heat wave' off Western Australia during the summer of 2010/11
Publication TypeGovernment Report
Year of Publication2011
AuthorsPearce, A, Lenanton R, Jackson G, Moore J, Feng M, Gaughan D
Departmentof Fisheries, WAD
PublisherWestern Australia Department of Fisheries
ISBN Number978-1-921845-25-3
Report Number222, 2011
Keywordsbiodiversity, heat wave, stress, temperature
Abstract* Water temperatures off the south-western coast of Western Australia rose to unprecedented levels during February and March 2011, and this warming event has been termed a “marine heat wave”. While surface temperatures were more than 3°C above the long-term monthly average over an extended area in February 2011, the temperature in some localised areas in coastal waters exceeded the long-term monthly average by 5°C for periods of a day or two in late February/early March. * A scientific Workshop was organised on Thursday 5 May, 2011 to review the oceanic processes and biological/fisheries consequences of the heat wave and to provide a means for capturing much of the anecdotal information. * This heat wave, which coincided with an extremely strong La Niña event and a record strength Leeuwin Current, is viewed as a major temperature anomaly superimposed on the underlying long-term ocean-warming trend. * While sudden changes in water temperature have been recorded in waters off the Western Australian coast in the past, there have been no previous records of such strongly elevated temperatures. * Biological effects reported to date include fish and invertebrate deaths, extensions and contractions in species distributions, variations in recruitment and growth-rates, impacts on trophic relationships and community structure, and variations in catch rates of exploited species. * As such, the elevated water temperatures were viewed as resulting either in mortality or in a variety of “sub-lethal” effects, both of which can have either short or long-term implications. * These observed and expected biological consequences are based primarily on anecdotal information collected during or directly after the passage of the heat wave. However, as results from ongoing research and monitoring programs become available, a more comprehensive and considered view of the effects will be forthcoming in the form of peer-reviewed journal papers. * While widespread mortality of fish and invertebrates were reported, none were shown to be attributable to disease. * It appears that the incursions of large volumes of silt-laden water from river outflows into the adjacent coastal waters of the mid-west coast between Dongara and NW Cape following the passage of the tropical cyclone Bianca in late January are also likely to have contributed to the mortality experienced by the marine biota of that region. * While the nature of the impacts will to a large extent dictate the type and degree of management response, most of the fishery responses identified in this report are currently covered in the ongoing monitoring and assessment protocols in place in the Department of Fisheries, noting that in particular, the response to mortality events is a well co-ordinated, interdepartmental process. * The two most urgent “Fisheries Management” actions are (a) the need to review the management (and future monitoring) arrangements for Area 8 of the Roe’s abalone fishery, and (b) to determine the consequences of any additional mortality of the 2010 rock lobster puerulus settlement.
Government BodyWestern Australia Department of Fisheries
Refereed DesignationUnknown
Marine heat wave off WA report.pdf636.11 KB