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LAND USE AND LOTIC DIATOM ASSEMBLAGES: A MULTI-SPATIAL AND TEMPORAL ASSESSMENT
Citation:
Pan, Y., A. T. Herlihy, P R. Kaufmann, P. J. WIGINGTON JR, J Van Sickle, AND T. Moser. LAND USE AND LOTIC DIATOM ASSEMBLAGES: A MULTI-SPATIAL AND TEMPORAL ASSESSMENT. Presented at Annual Meeting of North American Benthological Society, Pittsburgh, PA, May 29-June 1, 2002.
Description:
We assessed the effects of land-use at multiple spatial scales (e.g., catchment, stream network, and stream reach) on periphyton from 25 wadeable streams along a land-use gradient in the Willamette River Basin, Oregon, in a dry season. Additional water chemistry samples were collected in the following wet season to assess temporal variation of the effects of the land-use on stream water chemistry. Diatom assemblages were characterized by halophilous taxa (72%). Correlations between diatom assemblages (species composition, metrics, and indices) and the land-use were overall weak in the dry season. Constrained canonical correspondence analysis and redundancy analysis showed that % of agriculture didn't explain significant amount of variance in diatom assemblages (<6%) and water chemistry data (<10%) regardless of the spatial scales in the dry season (p>0.05, Monte Carlo permutation tests). In the wet season, % agriculture in the catchment, however, explained 26% of variance in the water chemistry data. Van Dam's diatom autecological metrics and Trophic Diatom Index better correlated with most of water chemistry variables (e.g., TP, TN, Conductivity, Cl) measured in the wet season than those in the dry season. Our data suggest that diatom assemblages may integrate the effects of the land-use on streams through time.