2007). A European water type characterization based on aquatic macro-invertebrate communities revealed that the species (or ‘best available’) taxonomic level was more informative than the family level, as the latter led to a less CB-839 molecular weight distinct separation of sites (Verdonschot 2006). It has been concluded that further studies are needed to reveal whether results are mere region-

or system-specific, or may reflect more generic patterns AZD3965 price (Biaggini et al. 2007; Moreno et al. 2008). Floodplains of large rivers are among the most fertile and richest ecosystems on earth, characterized by very high landscape and biological diversity (Robinson et al. 2002; Ward et al. 2002). Nevertheless, these systems have been poorly investigated with respect to the taxonomic level most appropriate for monitoring biotic properties. Using 4-Hydroxytamoxifen datasheet a lowland floodplain area along the river Rhine for data collection, the present study aimed to compare four arthropod datasets of different taxonomic detail on their discriminatory power for various environmental factors. The arthropod datasets comprised ground-dwelling arthropods at class-order level, beetle families, ground beetle genera and ground beetle species. The choice for beetles and ground beetles was made because they are relatively easy to identify and because they tend to show clear responses to a variety of environmental characteristics (Biaggini et al. 2007; Irmler 2003; Pohl et al. 2007;

Uehara-Prado et al. 2009). The environmental conditions investigated included vegetation characteristics, hydro-topographic setting, physical–chemical soil properties and soil contamination levels. To relate the arthropod assemblages to these environmental characteristics, the method of variance for partitioning was used. This is a multivariate statistical approach designed to attribute variation in community composition to specific explaining variables and thus particularly suited to assess the importance of different environmental factors relative to each other (Borcard et al. 1992; Peeters et al. 2000). Methods Study area The river Rhine is one

of the longest and most important rivers in Europe, flowing from the Swiss Alps via Germany and The Netherlands to the North Sea. Shortly downstream of the border between Germany and The Netherlands, the Rhine splits in three main distributaries, i.e. the Waal, the Nederrijn and the IJssel (Fig. 1). The floodplains along these distributaries are generally embanked and cultivated. During the past century, large amounts of contaminated river sediment have been deposited in these areas (Middelkoop 2000). This has resulted in elevated concentrations of several contaminants, notably heavy metals, in the floodplain soils. Fig. 1 Location of the study area ‘Wolfswaard’ The ‘Wolfswaard’ floodplain area (51o57′19″N; 5o39′3″E) is located south of the city of Wageningen along the Nederrijn distributary (Fig. 1). The study area is embanked by a winter dike.