Going with the flow: The case of three tropical reef fish transported to cool temperate waters following an extreme marine heatwave

The extreme marine heatwave of 2010/11 off Western Australia, and the anomalously high water temperatures in 2011/12 and 2012/13 were attributable, in part, to the out-of-season, pole-ward flowing Leeuwin Current (LC). While this event devastated some regional fisheries, it led to increased recruitment and/or large range extensions of tropical marine taxa in more southern, temperate waters. Three large-bodied tropical reef fishes, Lutjanus malabaricus, Pinjalo pinjalo and Lethrinus nebulosus, were caught in temperate waters off southern Western Australia, similar to 1000-1500 km from their typical tropical habitats. Estimated ages of 8 to 9 years indicate they were spawned in the 2011/2012 or 2012/2013 austral spring/summer spawning periods. Swimming speed of late-stage larvae combined with the LC speed would have facilitated long-distance dispersal of larvae to temperate waters, where elevated water temperatures throughout the year, but particularly warmer winter months during their first 1-2 years of life, would have enabled these vagrant species to acclimatise to temperate waters.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

The extreme marine heatwave off Western Australia in 2010/11, and the high water temperatures in 2011/12 and 2012/13, were partly caused by the out-of-season pole-ward flowing Leeuwin Current. While the event had negative impacts on some fisheries, it also led to increased recruitment and range extensions of tropical marine species in temperate waters. Three large-bodied tropical reef fish were caught in temperate waters off southern Western Australia, far from their usual tropical habitats. The fish were spawned during the 2011/2012 or 2012/2013 austral spring/summer spawning periods, and their ability to acclimatize to the temperate waters was facilitated by the combination of larval swimming speed and the speed of the Leeuwin Current.