Miss Océane Attlan1, Miss Karen Filbee-Dexter1,2, Mr Albert Pessarrodona1, Mr Néstor E. Bosch1,3, Miss Sahira Y. Bell1,4, Mr Thomas Wernberg1,2
1UWA Oceans institue and School of Biological Sciences, University of Crawley, Perth, Australia, 2Institute of Marine Research, His, Norway, 3Universidad de Las Palmas de Gran Canaria , , Spain, 4Department of Conservation, Biodiversity and Attractions, Kensington, Australia
Marine habitats are experiencing a wide array of changes due to ocean temperature rise. Western Australia’s temperate reefs have experienced losses of cool-affinity kelps and associated fauna at their warm-edge range, and increased abundance of tropical species. While tropical species are hypothesized to play important roles in the dynamics of these systems, the ecosystem-scale consequences of their shifts are poorly understood. This is particularly true for highly mobile species such as reef fishes, which may show variations in abundance in marginal habitats and may have a variable effect on ecosystem function.
Here, we investigate the impacts of warming and marine heatwaves on marine fish assemblages, their standing biomass and productivity over time. To do so, we use time series of standardized surveys of reef fishes spanning >15 years of ocean temperature change. We complement our observations with a space-for-time substitution approach across multiple locations spanning a thermal latitudinal gradient over 2,000 km of coastline. Three to six sites were sampled in each location using diver-operated video (DOV) surveys. Eight transects of 25 by 5m were swum at each site, with fish species and their size being measured in the program EventMeasure. We then used the length-biomass relationships to obtain assemblage standing biomass and used a novel individual-level modelling approach that combines estimates of fish growth and mortality to estimate assemblage productivity.
Describing the marine habitats and assessing changes will help to predict the future of Western Australia marine landscapes’ and therefore will lead to implement new tools for wildlife conservation and marine ecosystem restoration programs.
Biography:
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