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Top-down and bottom-up control of litter decomposers in streams

Gonçalves, Ana Lúcia and Chauvet, Eric and Bärlocher, Felix and Graça, Manuel A. S. and Canhoto, Cristina Top-down and bottom-up control of litter decomposers in streams. (2014) Freshwater Biology, 59 (10). 2172-2182. ISSN 0046-5070

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Official URL: http://dx.doi.org/10.1111/fwb.12420

Abstract

1. Detritivores preferentially consume certain aquatic hyphomycete species while rejecting others. Fungal identity may therefore be a crucial factor determining stream food-web structure and complexity and extend the impact of microbial diversity to effects up through the food web. 2. In this study, we examined if shredder feeding is affected by the identity of fungi on leaves (bottom-up effects) and if preferences of shredders for particular fungi affect the composition of fungal assemblages (top-down effects). Oak leaf discs were conditioned in microcosms with six individual fungal species previously reported as highly palatable (P), unpalatable/rejected (R) and intermediate (I). Additionally, three microcosms were inoculated with three mixtures of four fungal species, each consisting of a different subset of the six species. 3. Colonised discs were offered to three detritivores with different feeding strategies: Proasellus sp. (Isopoda), Echinogammarus meridionalis (Amphipoda) and Schizopelex festiva (Trichoptera). When offered leaves colonised by single fungal species, consumption rates by E. meridionalis and S. festiva were higher on I, followed by P and, finally, R species. Consumption rates by Proasellus sp. were sim- ilar across fungal treatments. Consumption rates by the three invertebrates were also similar across all fungal multispecies treatments, suggesting that invertebrate preferences for, or rejection of, a given fungal species may be masked when it grows in proximity to other fungi. Composition and structure of fungal communities were not significantly affected by the feeding of any of the three invertebrates. 4. Our results suggest that certain combinations of fungal and detritivore species result in unpredictable bottom-up and top-down effects in stream food webs.

Item Type:Article
Additional Information:Thanks to Wiley editor. The definitive version is available at http://onlinelibrary.wiley.com The original PDF of the article can be found at Wiley Online Library website : http://onlinelibrary.wiley.com/doi/10.1111/fwb.12420/epdf
HAL Id:hal-01142618
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Universidade de Coimbra (PORTUGAL)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Mount Allison University - MTA (CANADA)
Laboratory name:
Funders:
NSERC Canada - Portuguese Science and Technology Foundation. Grant Number: SFRH/BD/47089/2008 - European Regional Development Fund (ERDF) - COMPETE – Operational Factors of Competitiveness Program (POFC-COMPETE). Grant Number: FCOMP-01-0124-FEDER-007112 - FCT – Foundation for Science and Technology, under the project ‘Predicting the effect of global warming on stream ecosystems’. Grant Number: PTDC/CLI/67180/2006 - Pessoa exchange programme between Portugal and France from the French Ministry of Foreign and European Affairs. Grant Number: PHC 22808 TB
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Deposited By: Eric Chauvet
Deposited On:15 Apr 2015 14:09

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