Mr Salvador Zarco Perello1, T Wernberh1, T Langlois1, M Vanderklift2, Tom Holmes3
1School of Biological Sciences and UWA Oceans Institute, The University of Western Australia, Crawley, Australia, 2Commonwealth Scientific and Industrial Research Organization (CSIRO), Crawley, Australia, 3Department of Biodiversity, Conservation and Attractions (DBCA), Kensington, Australia
As ocean temperatures rise and the transport of warm waters to temperate ecosystems intensifies, the poleward expansion of tropical marine species is increasing. The poleward migration and establishment of tropical herbivorous species are of special concern since they can modify the community structure of temperate ecosystems by increasing the consumption of the habitat-forming macrophytes typical of those environments. In Western Australia the tropical herbivore Siganus fuscescens (rabbitfish) made a swift poleward range expansion to higher latitudes in 2011 following a marine heatwave. Since then, populations of this tropical herbivore have been reported in the region but despite its potential to impact the structure and function of temperate ecosystems, we know little of their current distribution patterns and feeding variability in temperate ecosystems. This study assessed the magnitude of the range expansion of rabbitfish in temperate Western Australia, their habitat associations and their variability in abundances and herbivory rates. Preliminary results show that rabbitfish are distributed widely in the region, with abundant populations persisting over the years along the latitudinal gradient. Big populations were associated with shallow rocky environments with brown seaweed and adjacent seagrass meadows; however, there are present in a variety of environments, including manmade structures. Feeding rates are positively correlated with abundance but also temperature, declining steeply in cold waters. The overwintering of abundant schools of rabbitfish at big spatial extents suggest that the ecosystems of the region have been more impacted than previously known and that the indirect effects of a marine heat-wave can be very pervasive.
Salvador Zarco-Perello is a marine biologist and PhD candidate at the UWA Oceans Institute and School of Biological Sciences of the University of Western Australia. His research interests focus on the conservation and understanding of the form and function of marine ecosystems, from tropical coral reefs and seagrass meadows to temperate kelp forests. Currently Salvador is researching the range-extension of tropical herbivorous fish to temperate ecosystems in Western Australia, the ecological drivers involved and its consequences for the habitat-forming macrophytes.