| |
Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Current and Future Approaches for Using Benthic Algae to Monitor and Assess Aquatic Ecosystems II
LAND USE AND LOTIC DIATOM ASSEMBLAGES: A MULTI-SPATIAL AND TEMPORAL ASSESSMENT.
Y. Pan1, A.T. Herlihy2, P.R. Kaufmann3, J. Wigington3, J. Van Sickle3, and T. Moser4. 1Environmental Sciences and Resources, Portland State University, Portland, OR 97207, USA, 2Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97333, USA, 3US Environmental Protection Agency, Corvallis, OR 97333, USA, 4Dynamac International Corp., Corvallis, OR 97333, USA
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 samples were collected in the following wet season to assess temporal variation in 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 land-use in the dry season were weak overall. Constrained canonical correspondence analysis and redundancy analysis showed that in the dry season % of agriculture didn't explain a significant amount of variance in diatom assemblages (<6%) and water chemistry data (<10%) regardless of the spatial scales (p>0.05, Monte Carlo permutation tests). In the wet season, however, % of agriculture in the catchment explained 26% of variance in the water chemistry data. Van Dam's diatom autecological metrics and Trophic Diatom Index better correlated with most of the 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.
|
|
