Research Repository

Temperature effects on fish production across a natural thermal gradient

O'Gorman, Eoin J and Ólafsson, Ólafur P and Demars, Benoît OL and Friberg, Nikolai and Guðbergsson, Guðni and Hannesdóttir, Elísabet R and Jackson, Michelle C and Johansson, Liselotte S and McLaughlin, Órla B and Ólafsson, Jón S and Woodward, Guy and Gíslason, Gísli M (2016) 'Temperature effects on fish production across a natural thermal gradient.' Global Change Biology, 22 (9). 3206 - 3220. ISSN 1365-2486

[img]
Preview
Text
Temperature effects on fish production across a natural thermal gradient.pdf - Published Version
Available under License Creative Commons Attribution.

Download (413kB) | Preview

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.

Item Type: Article
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 17 Jul 2019 13:55
Last Modified: 13 Aug 2019 16:15
URI: http://repository.essex.ac.uk/id/eprint/24431

Actions (login required)

View Item View Item