Effects of intense agricultural practices on heterotrophic processes in streams |
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Authors: | Christophe Piscart Romuald Genoel Eric Chauvet |
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Institution: | a Université Claude Bernard Lyon 1 - Laboratoire d'Ecologie des Hydrosystèmes Fluviaux - UMR CNRS 5023 - Campus Doua, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France b Université de Rennes 1 - UMR CNRS ECOBIO 6553 - Campus Beaulieu, 263 Av. du Général Leclerc, 35042 Rennes Cedex, France c Université Paul Sabatier de Toulouse - Laboratoire EcoLab - UMR CNRS 5245, 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4, France |
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Abstract: | In developed countries, changes in agriculture practices have greatly accelerated the degradation of the landscape and the functioning of adjacent aquatic ecosystems. Such alteration can in turn impair the services provided by aquatic ecosystems, namely the decomposition of organic matter, a key process in most small streams. To study this alteration, we recorded three measures of heterotrophic activity corresponding to microbial hydrolasic activity (FDA hydrolysis) and leaf litter breakdown rates with (kc) and without invertebrates (kf) along a gradient of contrasted agricultural pressures. Hydrolasic activity and kf reflect local/microhabitat conditions (i.e. nutrient concentrations and organic matter content of the sediment) but not land use while kc reflects land-use conditions. kc, which is positively correlated with the biomass of Gammaridae, significantly decreased with increasing agricultural pressure, contrary to the taxonomic richness and biomass of Trichoptera and Plecoptera. Gammaridae may thus be considered a key species for organic matter recycling in agriculture-impacted streams. |
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Keywords: | Land use Nutrient Leaf litter breakdown Macroinvertebrates Hydrolasic activity |
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