Consistent temperature dependence of respiration across ecosystems contrasting in thermal history |
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Authors: | Daniel M. Perkins Gabriel Yvon‐Durocher Benoît O.L. Demars Julia Reiss Doris E. Pichler Nikolai Friberg Mark Trimmer Guy Woodward |
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Affiliation: | 1. School of Biological and Chemical Sciences, Queen Mary University of London, , London, UK;2. Ecological Sciences Group, The James Hutton Research Institute, , Craigiebuckler, Aberdeen, AB15 8QH UK;3. Department of Life Sciences, Whitelands College, University of Roehampton, , London, SW15 4JD UK;4. Department of Freshwater Ecology, Aarhus University, National Environmental Research Institute, , DK‐8600 Silkeborg, Denmark |
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Abstract: | Ecosystem respiration is a primary component of the carbon cycle and understanding the mechanisms that determine its temperature dependence will be important for predicting how rates of carbon efflux might respond to global warming. We used a rare model system, comprising a network of geothermally heated streams ranging in temperature from 5 °C to 25 °C, to explore the nature of the relationship between respiration and temperature. Using this ‘natural experiment’, we tested whether the natal thermal regime of stream communities influenced the temperature dependence of respiration in the absence of other potentially confounding variables. An empirical survey of 13 streams across the thermal gradient revealed that the temperature dependence of whole‐stream respiration was equivalent to the average activation energy of the respiratory complex (0.6–0.7 eV). This observation was also consistent for in‐situ benthic respiration. Laboratory experiments, incubating biofilms from four streams across the thermal gradient at a range of temperatures, revealed that the activation energy and Q10 of respiration were remarkably consistent across streams, despite marked differences in their thermal history and significant turnover in species composition. Furthermore, absolute rates of respiration at standardised temperature were also unrelated to ambient stream temperature, but strongly reflected differences in biofilm biomass. Together, our results suggest that the core biochemistry, which drives the kinetics of oxidative respiratory metabolism, may be well conserved among diverse taxa and environments, and that the intrinsic sensitivity of respiration to temperature is not influenced by ambient environmental temperature. |
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Keywords: | carbon cycle community composition ecosystem functioning geothermal streams global warming metabolic theory of ecology respiration temperature |
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