Physical and chemical water requirements of the white-clawed crayfish (Austropotamobius pallipes) in western France

1. In France, the distribution of the native white-clawed crayfish (Austropotamobius pallipes) is restricted, fragmented and mainly located in headwater streams. To conserve this indigenous species, it is necessary to characterize its habitat preferences. 2. Seven brooks in the Deux-Sevres Departement (western France) containing wild populations of A. pallipes were studied to determine its ranges of tolerance to 19 physical and chemical water parameters. On two brooks, the Sevre Nantaise and the Verdonniere, sites with and without A. pallipes were compared. Each site was sampled twice monthly from November 2002 to November 2004. 3. It was found that the white-clawed crayfish was able to tolerate wide ranges of values of some of the measured parameters. The Magot site harboured the largest A. pallipes population (17.5 crayfish m(-2)) and had dissolved oxygen concentrations as low as 4.93mgL(-1), while water temperature rose above 20 degrees C for several consecutive days during summer and nitrate concentrations were always found to be above 30mgL(-1). These unusual findings could call into question the status of A. pallipes as a bioindicator of good water quality. 4. Principal component analyses (PCA) suggested that an increase of organic matter was a discriminant factor for the presence or absence of A. pallipes. In addition, sites with and without crayfish on the Sevre Nantaise brook showed showed significant differences (p < 0.05) in total organic carbon (TOC), and those on the Verdonniere brook in turbidity and total suspended solids (TSS). Copyright (c) 2006 John Wiley & Sons, Ltd.