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Litter identity mediates predator impacts on the functioning of an aquatic detritus-based food web

Jabiol, Jérémy and Cornut, Julien and Danger, Michael and Jouffroy, Marion and Elger, Arnaud and Chauvet, Eric Litter identity mediates predator impacts on the functioning of an aquatic detritus-based food web. (2014) Oecologia, vol. 176 (n° 1). pp. 225-235. ISSN 0029-8549

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Official URL: http://dx.doi.org/10.1007/s00442-014-2990-y

Abstract

During past decades, several mechanisms such as resource quality and habitat complexity have been proposed to explain variations in the strength of trophic cascades across ecosystems. In detritus-based headwater streams, litter accumulations constitute both a habitat and a resource for detritivorous macroinvertebrates. Because litter edibility (which promotes trophic cascades) is usually inversely correlated with its structural complexity (which weakens trophic cascades), there is a great scope for stronger trophic cascades in litter accumulations that are dominated by easily degradable litter species. However, it remains unclear how mixing contrasting litter species (conferring both habitat complexity and high quality resource) may influence top–down controls on communities and processes. In enclosures exposed in a second-order stream, we manipulated litter species composition by using two contrasting litter (alder and oak), and the presence–absence of a macroinvertebrate predator (Cordulegaster boltonii larvae), enabling it to effectively exert predation pressure, or not, on detritivores (consumptive versus non-consumptive predation effects). Leaf mass loss, detritivore biomass and community structure were mostly controlled independently by litter identity and mixing and by predator consumption. However, the strength of predator control was mediated by litter quality (stronger on alder), and to a lesser extent by litter mixing (weaker on mixed litter). Refractory litter such as oak leaves may contribute to the structural complexity of the habitat for stream macroinvertebrates, allowing the maintenance of detritivore communities even when strong predation pressure occurs. We suggest that considering the interaction between top–down and bottom–up factors is important when investigating their influence on natural communities and ecosystem processes in detritus-based ecosystems.

Item Type:Article
Additional Information:Thanks to Springer editor. The definitive version is available at http://link.springer.com The original PDF of the article can be found at Springer website : http://link.springer.com/article/10.1007%2Fs00442-014-2990-y/pii/S0009261400005583
HAL Id:hal-01142917
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université de Lorraine (FRANCE)
Laboratory name:
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Deposited By: Eric Chauvet
Deposited On:16 Apr 2015 10:17

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