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Community size structure varies with predator-prey size relationships and temperature across Australian reefs
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  • Amy Coghlan,
  • Julia Blanchard,
  • Freddie Heather,
  • Rick Stuart-Smith,
  • Graham Edgar,
  • Asta Audzijonyte
Amy Coghlan
University of Tasmania School of Natural Sciences

Corresponding Author:[email protected]

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Julia Blanchard
University of Sheffield
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Freddie Heather
University of Tasmania School of Natural Sciences
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Rick Stuart-Smith
University of Tasmania
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Graham Edgar
University of Tasmania
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Asta Audzijonyte
University of Tasmania
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Climate change and fisheries exploitation are dramatically changing the species composition, abundances, and size spectra of fish communities. We explore whether variation in abundance-size spectra, a widely studied ecosystem feature, is influenced by a critical parameter thought to govern the shape of size-structured ecosystems—the relationship between the sizes of predators and their prey (predator-prey mass ratios, or PPMRs). PPMR estimates are lacking for vast numbers of fish species, including at the broader trophic guild scale. Using measurements of 8,128 prey items in gut contents of 97 reef fish species, we established PPMRs for four major trophic guilds (piscivores, invertivores, planktivores and herbivores) using linear mixed effects models. To assess theoretical predictions that higher mean community-level PPMR leads to shallower size spectrum slopes, we compared observations of mean community-level PPMR with size spectrum slopes for coastal reef sites distributed around Australia. PPMRs of individual fishes were remarkably high (median ~71,000), with significant variation between different trophic guilds (~890 for piscivores; ~83,000 for planktivores), and ~8,700 for whole communities. Community-level PPMRs were positively related to size spectrum slopes, broadly consistent with theory, however, this pattern was also influenced by the latitudinal temperature gradient. Tropical reefs showed a stronger relationship between community-level PPMRs and community size spectrum slopes than temperate reefs. The extent that these patterns apply outside Australia, and consequences for community structure and dynamics, are key areas for future investigation.
09 Mar 2022Submitted to Ecology and Evolution
09 Mar 2022Submission Checks Completed
09 Mar 2022Assigned to Editor
09 Mar 2022Review(s) Completed, Editorial Evaluation Pending
11 Mar 2022Editorial Decision: Revise Minor
12 Mar 20221st Revision Received
12 Mar 2022Submission Checks Completed
12 Mar 2022Assigned to Editor
12 Mar 2022Review(s) Completed, Editorial Evaluation Pending
15 Mar 2022Editorial Decision: Accept