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Headwater reservoirs weaken terrestrial-aquatic linkage by slowing leaf-litter processing in downstream regulated reaches

Authors

  • C. Mendoza–Lera,

    1. Department of Freshwater Conservation, Brandenburg University of Technology Cottbus, Seestraße 45, D-15526 Bad Saarow, Germany
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  • A. Larrañaga,

    Corresponding author
    1. Laboratory of Stream Ecology, Department of Plant Biology and Ecology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
    • Laboratory of Stream Ecology, Department of Plant Biology and Ecology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain.
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  • J. Pérez,

    1. Laboratory of Stream Ecology, Department of Plant Biology and Ecology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
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  • E. Descals,

    1. Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC), Miquel Marquès 21, 07190 Esporles (Mallorca), Spain
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  • A. Martínez,

    1. Laboratory of Stream Ecology, Department of Plant Biology and Ecology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
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  • O. Moya,

    1. Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC), Miquel Marquès 21, 07190 Esporles (Mallorca), Spain
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  • I. Arostegui,

    1. Department of Applied Mathematics, Statistics and Operational Research, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
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  • J. Pozo

    1. Laboratory of Stream Ecology, Department of Plant Biology and Ecology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
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Abstract

Leaf litter breakdown is a key process, providing matter and energy to communities inhabiting many headwater streams that flow through forests. This detrital pathway is affected by many human landscape transformations; but it is little known about the impact of small headwater reservoirs on leaf litter decay in streams. Alder leaf litter breakdown rates and associated fauna were studied upstream and downstream of five small water supply reservoirs (surface-release in rainy autumn-winters), in the Nerbioi-Ibaizabal drainage basin (Basque Country, Spain), to assess the effect of impoundment on headwater streams function. Breakdown rates were significantly lower below the dams, mainly associated with a reduction of the density and the biomass of shredders. Among the shredders, Nemouridae and especially Protonemura were less abundant downstream of the dam. Alterations in the physicochemical characteristics of the water due to the reservoirs were negligible throughout our study, and temperature showed only slight variations that could not explain the reduction of the rates. The effect on shredders is likely to be related to differences in the riparian environment and flow regulation by the dams. Copyright © 2010 John Wiley & Sons, Ltd.

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