Thursday, May 29, 2008 - 10:00 AM
530

Additive partitioning of diatom, macroinvertebrate, macrophytes, and fish diversity in european streams

Sonja Stendera, Dept. of Environmental Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, 74850 Uppsala, Sweden

In order to develop and test hypotheses about processes responsible for the increasing biodiversity loss in running waters, it is crucial to understand spatial variation in diversity across multiple scales. In linking freshwater biota diversity patterns to ecoregional environmental heterogeneity, the combined analyses of local-regional species richness (LSR-RSR) and the additive partitioning of diversity is an excellent tool to get more insight into diversity patterns of freshwater communities across spatial scales. This combination was applied four stream organism groups (diatoms, macroinvertebrates, macrophytes, and fish) on European lowland streams of high ecological status. Within-site (alpha) diversity was small and between-site (beta) was large indicating high diversity between sites possible due to high environmental heterogeneity.  2 LSR-RSR relationships were significant; diatoms seemed to be influenced by the regional pool showing a linear pattern, whereas the curvilinear pattern of macroinvertebrates indicated that local factors might be more important for predicting local diversity. These results indicate equivocacy, i.e. communities were both influenced by both regional and local factors. Nevertheless, the diversity patterns of the stream communities analyzed here are consistent with hierarchy theory, i.e. there is a nested hierarchy of multiple scales over which ecological processes structuring species composition at a site.


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