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RELATIONSHIPS BETWEEN ENVIRONMENTAL VARIABLES AND BENTHIC DIATOM ASSEMBLAGES IN CALIFORNIA CENTRAL VALLEY STREAMS (USA)
Citation:
Pan, Y., B. H. Hill, P. Husby, R K. Hall, AND P R. Kaufmann. RELATIONSHIPS BETWEEN ENVIRONMENTAL VARIABLES AND BENTHIC DIATOM ASSEMBLAGES IN CALIFORNIA CENTRAL VALLEY STREAMS (USA). HYDROBIOLOGIA 561(1):119-130, (2006).
Impact/Purpose:
To study distributional patterns of benthic diatom assemblages in relation to environmental characteristics in streams and rivers of the California Central Valley Ecoregion
Description:
Streams and rivers in the California Central Valley Ecoregion have been substantially modified by human activities. This study examines distributional patterns of benthic diatom assemblages in relation to environmental characteristics in streams and rivers of this region. Benthic diatoms, water quality, and physical habitat conditions were characterized from 53 randomly selected sites. Sampled sites varied considerably in stream types, physical habitat conditions, and water quality. Only 28% of sampled sites were modified to relatively unmodified natural stream or river channels while 66% of all sites were man-made waterways (ditches and drains). Stream sites were characterized by low mid-channel canopy cover and high channel substrate embeddedness. The waters at these sites were enriched with minerals, and turbidity varied from 1.3 to 185.0 NTU with an average of 13.5 NTU. A total of 249 diatom taxa were identified. Average taxa richness was 41 with a range of 7 to 76. The assemblages were dominated by Stauosira construens (11%), Epithemia sorex (8%), Cocconeis placentula (7%), and Nizschia amphibia (6%). Multivariate analyses (cluster analysis, classification tree analysis, and canonical correspondence analysis) all showed that benthic diatom assemblages were mainly associated with channel morphology, in-stream habitat, and riparian conditions. Our results suggest that benthic diatoms can be used for assessing physical habitat alterations in streams.