Assessing the size structured pelagic ecosystems in the western Tasman Sea: A stable isotope analysis — ASN Events

Assessing the size structured pelagic ecosystems in the western Tasman Sea: A stable isotope analysis (#176)

Lucas Kas 1 , Debashish Mazumder 2 , Jason Evertt 3 , Lian Kwong 4 , Iain M Suthers 1
  1. Biological Earth and Environmental Sciences, UNSW, Sydney, nsw, 2052
  2. Australian Nuclear Science & Technology Organisation, Sydney, NSW, Australia
  3. University of New South Wales, Sydney, NSW, Australia
  4. Department of Oceanography, University of British Columbia, Canada

Ocean fisheries are increasingly managed by satellite imagery of sea level and sea surface temperature, but the ecosystem basis to these oceanic habitats in unknown. Mesoscale eddies are common features off Australia’s East coast, providing distinct oceanographic habitats, with the direction of their rotation having powerful biological implications. This research will link size-based ecosystems of the western Tasman Sea, with tropic level estimates based on nitrogen stable isotopes composition of the major functional groups, to determine the trophic ecology of each oceanic environment. Trophic ecology and function can be revealed by quantifying a set of numerical food web parameters established from the relationship between body size and trophic level, such as: food chain length, trophic efficiency, and predator-prey mass ratios. The results displayed elevated trophic levels and lower abundance in the anti-cyclonic eddy environment compared with the cyclonic eddy across the entire size-structured study community from mesozooplankton to midwater fish.  Anticyclonic eddy environments also returned higher predator-prey mass ratios and decreased trophic efficiency. These ecosystem metrics further our understanding of the effect of coastal ocean warming off eastern Australia,  while information on the biomass, productivity, and resilience of each ecosystem, will to be used improve fisheries management.

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