Global warming may disproportionately affect larger adults in a predatory coral reef fish

Messmer, Vanessa, Pratchett, Morgan S., Hoey, Andrew S., Tobin, Andrew J., Coker, Darren J., Cooke, Steven J., and Clark, Timothy D. (2017) Global warming may disproportionately affect larger adults in a predatory coral reef fish. Global Change Biology, 23 (6). pp. 2230-2240.

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Global warming is expected to reduce body sizes of ectothermic animals. Although the underlying mechanisms of size reductions remain poorly understood, effects appear stronger at latitudinal extremes (poles and tropics) and in aquatic rather than terrestrial systems. To shed light on this phenomenon, we examined the size dependence of critical thermal maxima (CTmax) and aerobic metabolism in a commercially important tropical reef fish, the leopard coral grouper (Plectropomus leopardus) following acclimation to current-day (28.5 degrees C) vs. projected end-of-century (33 degrees C) summer temperatures for the northern Great Barrier Reef (GBR). CTmax declined from 38.3 to 37.5 degrees C with increasing body mass in adult fish (0.45-2.82 kg), indicating that larger individuals are more thermally sensitive than smaller conspecifics. This may be explained by a restricted capacity for large fish to increase mass-specific maximum metabolic rate (MMR) at 33 degrees C compared with 28.5 degrees C. Indeed, temperature influenced the relationship between metabolism and body mass (0.02-2.38 kg), whereby the scaling exponent for MMR increased from 0.74 +/- 0.02 at 28.5 degrees C to 0.79 +/- 0.01 at 33 degrees C, and the corresponding exponents for standard metabolic rate (SMR) were 0.75 +/- 0.04 and 0.80 +/- 0.03. The increase in metabolic scaling exponents at higher temperatures suggests that energy budgets may be disproportionately impacted in larger fish and contribute to reduced maximum adult size. Such climate-induced reductions in body size would have important ramifications for fisheries productivity, but are also likely to have knock-on effects for trophodynamics and functioning of ecosystems.

Item ID: 50338
Item Type: Article (Research - C1)
ISSN: 1365-2486
Keywords: body size, climate change, critical thermal maximum, Great Barrier Reef, metabolic rate, Plectropomus leopardus, thermal tolerance
Funders: Lizard Island Research Station, Australian Museum (AM), Peter Teakle Sustainable Fishing Research Grant from the Lizard Island Research Station (LIRS) of the Australian Museum, FRDC-DCCEE, Smart Futures Fellowship
Projects and Grants: AM Isobel Bennett Marine Biology 2012 Postdoctoral Fellowship
Date Deposited: 20 Sep 2017 08:02
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 50%
41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960305 Ecosystem Adaptation to Climate Change @ 50%
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