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Direct and indirect effects of temperature on the population dynamics and ecosystem functioning of aquatic microbial ecosystems


Beveridge, Oliver S; Petchey, Owen L; Humphries, Stuart (2010). Direct and indirect effects of temperature on the population dynamics and ecosystem functioning of aquatic microbial ecosystems. Journal of Animal Ecology, 79(6):1324-1331.

Abstract

1. While much is known about the direct effect that temperature can have on aquatic communities, less is known about its indirect effect via the temperature dependence of viscosity and temperature-dependent trophic interactions.

2. We manipulated the temperature (5–20 °C) and the viscosity (equivalent to 5–20 °C) of water in laboratory-based bacteria–protist communities. Communities contained food chains with one, two or three trophic levels. Responses measured were population dynamics (consumer carrying capacity and growth rate, average species population density, and the coefficient of variation of population density through time) and ecosystem function (decomposition).

3. Temperature, viscosity and food chain length produced significant responses in population dynamics. Temperature-dependent viscosity had a significant effect on the carrying capacity and growth rates of consumers, as well as the average density of the top predator. Overall, indirect effects of temperature via changes in viscosity were subtle in comparison to the indirect effect of temperature via trophic interactions.

4. Our results highlight the importance of direct and indirect effects of temperature, mediated through trophic interactions and physical changes in the environment, both for population dynamics and ecosystem processes. Future mechanistic modelling of effects of environmental change on species will benefit from distinguishing the different mechanisms of the overall effect of temperature.

Abstract

1. While much is known about the direct effect that temperature can have on aquatic communities, less is known about its indirect effect via the temperature dependence of viscosity and temperature-dependent trophic interactions.

2. We manipulated the temperature (5–20 °C) and the viscosity (equivalent to 5–20 °C) of water in laboratory-based bacteria–protist communities. Communities contained food chains with one, two or three trophic levels. Responses measured were population dynamics (consumer carrying capacity and growth rate, average species population density, and the coefficient of variation of population density through time) and ecosystem function (decomposition).

3. Temperature, viscosity and food chain length produced significant responses in population dynamics. Temperature-dependent viscosity had a significant effect on the carrying capacity and growth rates of consumers, as well as the average density of the top predator. Overall, indirect effects of temperature via changes in viscosity were subtle in comparison to the indirect effect of temperature via trophic interactions.

4. Our results highlight the importance of direct and indirect effects of temperature, mediated through trophic interactions and physical changes in the environment, both for population dynamics and ecosystem processes. Future mechanistic modelling of effects of environmental change on species will benefit from distinguishing the different mechanisms of the overall effect of temperature.

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Additional indexing

Item Type:Journal Article, not refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Uncontrolled Keywords:Colpidium striatum; Didinium nasutum;ecosystem functioning;indirect and direct temperature effects; trophic interactions;viscosity
Language:English
Date:2010
Deposited On:07 May 2012 15:44
Last Modified:05 Apr 2016 15:45
Publisher:Wiley-Blackwell
ISSN:0021-8790
Publisher DOI:https://doi.org/10.1111/j.1365-2656.2010.01741.x
Other Identification Number:WOS:000283074000019

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Content: Supplemental Material
Filetype: PDF (Appendix S1. Summary of preliminary experiments to test the toxicology of Ficoll with respect to protists (Colpidium striatum).) - Registered users only
Size: 117kB
Content: Supplemental Material
Filetype: PDF (Fig. S1. Visual summary of post hoc multiple comparisons (Tukey’s HSD), average density (left-hand column) and CV (right-hand column).) - Registered users only
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Content: Supplemental Material
Filetype: PDF (Fig. S2. Visual summary of post hoc multiple comparisons (Tukey’s HSD), of proportion mass loss of wheat grains.) - Registered users only
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