Scale-dependent effects of land cover on water physico-chemistry and diatom-based metrics in a major river system, the Adour-Garonne basin (South Western France)
DOI: 10.1016/j.scitotenv.2013.06.107
Title: Scale-dependent effects of land cover on water physico-chemistry and diatom-based metrics in a major river system, the Adour-Garonne basin (South Western France)
Journal Title: Science of The Total Environment
Volume:
Publication Date: 1 January 2014
Start Page: 47
End Page: 55
Published online: online 25 July 2013
ISSN: 0048-9697
Author: Loï;c Tudesqueab, Clé;ment Tisseuilab, Sovan Lekab
Affiliations:

  • a CNRS, Université Paul Sabatier, ENFA, UMR5174 EDB (Laboratoire Évolution & Diversité Biologique), 118 route de Narbonne, F-31062 Toulouse, France

  • b Université Toulouse 3 Paul Sabatier, CNRS, UMR5174 EDB, F-31062 Toulouse, France
  • Abstract: e dependence of ecological phenomena remains a central issue in ecology. Particularly in aquatic ecology, the consideration of the accurate spatial scale in assessing the effects of landscape factors on stream condition is critical. In this context, our study aimed at assessing the relationships between multi-spatial scale land cover patterns and a variety of water quality and diatom metrics measured at the stream reach level. This investigation was conducted in a major European river system, the Adour-Garonne river basin, characterized by a wide range of ecological conditions. Redundancy analysis (RDA) and variance partitioning techniques were used to disentangle the different relationships between land cover, water-chemistry and diatom metrics.Our results revealed a top-down “cascade effect” indirectly linking diatom metrics to land cover patterns through water physico-chemistry, which occurred at the largest spatial scales. In general, the strength of the relationships between land cover, physico-chemistry, and diatoms was shown to increase with the spatial scale, from the local to the basin scale, emphasizing the importance of continuous processes of accumulation throughout the river gradient. Unexpectedly, we established that the influence of land cover on the diatom metric was of primary importance both at the basin and local scale, as a result of discontinuous but not necessarily antagonist processes. The most detailed spatial grain of the Corine land cover classification appeared as the most relevant spatial grain to relate land cover to water chemistry and diatoms.Our findings provide suitable information to improve the implementation of effective diatom-based monitoring programs, especially within the scope of the European Water Framework Directive.
    Accepted: 26 June 2013
    Received: 19 March 2013
    Revised: 21 June 2013
    Tel: +?33 561556911.Copyright ©
    Email: loic.tudesque@univ sovan.lek@univ

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