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Temperature effects on fish production across a natural thermal gradient

Temperature effects on fish production across a natural thermal gradient

Title: Temperature effects on fish production across a natural thermal gradient
Author: O'Gorman, Eoin J.
Ólafsson, Ólafur P.
Demars, Benoît O. L.
Friberg, Nikolai
Guðbergsson, Guðni
Hannesdóttir, Elísabet R.
Jackson, Michelle C.
Johansson, Liselotte S.
McLaughlin, Órla B.
Ólafsson, Jón S.
... 2 more authors Show all authors
Date: 2016-03
Language: English
Scope: 3206-3220
University/Institute: Háskóli Íslands
University of Iceland
School: Verkfræði- og náttúruvísindasvið (HÍ)
School of Engineering and Natural Sciences (UI)
Department: Líf- og umhverfisvísindadeild (HÍ)
Faculty of Life and Environmental Sciences (UI)
Series: Global Change Biology;22
ISSN: 1354-1013
DOI: 10.1111/gcb.13233
Subject: Natural experiment; Arctic; Hengill; Freshwater; Salmo trutta fario; Tilraunir; Vatn; Silungur; Vistfræði; Ecology
URI: https://hdl.handle.net/20.500.11815/180

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O'Gorman, E. J., Ólafsson, Ó. P., Demars, B. O. L., Friberg, N., Guðbergsson, G., Hannesdóttir, E. R., Jackson, M. C., Johansson, L. S., McLaughlin, Ó. B., Ólafsson, J. S., Woodward, G. and Gíslason, G. M. (2016), Temperature effects on fish production across a natural thermal gradient. Glob Change Biol, 22: 3206–3220. doi:10.1111/gcb.13233


Global warming is widely predicted to reduce the biomass production of top predators, or even result in species loss.Several exceptions to this expectation have been identified, however, and it is vital that we understand the underlyingmechanisms if we are to improve our ability to predict future trends. Here, we used a natural warming experiment inIceland and quantitative theoretical predictions to investigate the success of brown trout as top predators across astream temperature gradient (4–25 °C). Brown trout are at the northern limit of their geographic distribution in thissystem, with ambient stream temperatures below their optimum for maximal growth, and above it in the warmeststreams. A five-month mark-recapture study revealed that population abundance, biomass, growth rate, and produc-tion of trout all increased with stream temperature. We identified two mechanisms that contributed to theseresponses: (1) trout became more selective in their diet as stream temperature increased, feeding higher in the foodweb and increasing in trophic position; and (2) trophic transfer through the food web was more efficient in the war-mer streams. We found little evidence to support a third potential mechanism: that external subsidies would play amore important role in the diet of trout with increasing stream temperature. Resource availability was also amplifiedthrough the trophic levels with warming, as predicted by metabolic theory in nutrient-replete systems. These resultshighlight circumstances in which top predators can thrive in warmer environments and contribute to our knowledgeof warming impacts on natural communities and ecosystem functioning.


© 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.This is an open access article under the terms of the Creative Commons Attribution License, which permits use,distribution and reproduction in any medium, provided the original work is properly cited

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