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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Community structure 2
Habitat and community structure along three glacial streams continuums
C. Ilg1, E. Castella1, F. Malard2, and M.-J. Dole-Olivier2. 1Laboratoire d'Ecologie et de Biologie Aquatique, Université de Genève, 18 chemin des Clochettes, CH - 1206 GENEVE, SWITZERLAND, 2 Université CLAUDE BERNARD, Lyon1, UMR CNRS 5023, Ecologie des Hydrosystèmes Fluviaux, 43 Bd du 11 Novembre 1918, F-69622 VILLEURBANNE Cedex
Longitudinal patterns of macroinvertebrate assemblages were compared along three glacial streams: the Mutt and the Rhône (Switzerland) and the Romanche (France). The studied stretches extended from the glacier snout to a distance of 3 km (Swiss sites) to 7 km (French site) from the glacier. Twelve to eighteen sampling stations were established along these stretches. The purpose was to identify local conditions, such as upwellings / downwellings that could interfere with the longitudinal increase in temperature and bed stability to explain variations in faunal assemblages. Taxonomic diversity and abundance increased in the 3 streams with the distance to the glacier but differences of faunal succession occurred between the streams. A Co-inertia analysis of the environmental and faunal data showed that the co-variation of the two data sets was highly significant. Distinctive environmental features induced by geology, stream morphology and flow paths partly explained the variations in the longitudinal distribution of macroinvertebrate assemblages. The Swiss and the French kryal streams belong to two ecoregions region with contrasting species pools. This explained some differences between the two stream groups. A comparison based upon functional groups was also used to avoid the bias of these taxonomic differences.
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