School of Life Sciences | University of Technology Sydney
September 15th | 09:00 am (CEST)
Poleward expatriation of tropical marine organisms is occurring globally, linked to climate change via strengthening of Western Boundary Currents (WBCs). In summer 2016, there was an unprecedented (in 18 years of monitoring) influx of coral-reef fish juveniles (“vagrants”) in temperate SE Australia. However, a large climate change-linked storm event (“East Coast low”) in June 2016 wiped out large numbers of these fishes over several days, as well as severely altering coastal habitat. Some taxa (e.g. Acanthuridae: surgeonfishes, key habitat modifiers) were decimated with up to 95% loss, while others (e.g. Pomacentridae: damselfishes, under 5% loss) fared better. The storm altered habitat (boulder “barens” were exposed by large-scale removal of macroalgae) with new barrens supporting over fifty times more tropical fish recruits in the following year (2017) than surrounding kelp-dominated areas. Fish were more vulnerable to storm effects in exposed habitats, and some species exhibited size-selective losses. Such climate-related storms can decouple links between poleward fish shifts and more predictable climate effects such as sea temperature rise.