Temperature effects on fish production across a natural thermal gradient

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Title: Temperature effects on fish production across a natural thermal gradient
Authors: O'Gorman, EJ
Ólafsson, Ó
Demars, BOL
Friberg, N
Guðbergsson, G
Hannesdóttir, ER
Jackson, MC
Johansson, LS
McLaughlin, Ó
Ólafsson, JS
Woodward, G
Gíslason, GM
Item Type: Journal Article
Abstract: 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 underlying mechanisms if we are to improve our ability to predict future trends. Here, we used a natural warming experiment in Iceland and quantitative theoretical predictions to investigate the success of brown trout as top predators across a stream temperature gradient (4-25 °C). Brown trout are at the northern limit of their geographic distribution in this system, with ambient stream temperatures below their optimum for maximal growth, and above it in the warmest streams. A five-month mark-recapture study revealed that population abundance, biomass, growth rate, and production of trout all increased with stream temperature. We identified two mechanisms that contributed to these responses: (1) trout became more selective in their diet as stream temperature increased, feeding higher in the food web and increasing in trophic position; and (2) trophic transfer through the food web was more efficient in the warmer streams. We found little evidence to support a third potential mechanism: that external subsidies would play a more important role in the diet of trout with increasing stream temperature. Resource availability was also amplified through the trophic levels with warming, as predicted by metabolic theory in nutrient-replete systems. These results highlight circumstances in which top predators can thrive in warmer environments and contribute to our knowledge of warming impacts on natural communities and ecosystem functioning.
Issue Date: 3-Mar-2016
Date of Acceptance: 10-Jan-2016
ISSN: 1365-2486
Publisher: Wiley
Start Page: 3206
End Page: 3220
Journal / Book Title: Global Change Biology
Volume: 22
Issue: 9
Copyright Statement: © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd. 1 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.
Sponsor/Funder: Natural Environment Research Council (NERC)
Natural Environment Research Council (NERC)
The Royal Society
Natural Environment Research Council (NERC)
Funder's Grant Number: NE/I009280/2
Keywords: Salmo trutta fario
PIT tag
ecosystem services
natural experiment
06 Biological Sciences
05 Environmental Sciences
Publication Status: Published
Appears in Collections:Faculty of Natural Sciences

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