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COMPARISON OF LARGE RIVER SAMPLING METHOD USING DIATOM METRICS
Citation:
Flotemersch, J E., K A. Blocksom, AND S DeCelles. COMPARISON OF LARGE RIVER SAMPLING METHOD USING DIATOM METRICS. Presented at EMAP Symposium, Kansas City, MO, May 7-9, 2002.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
We compared the results of four methods used to assess the algal communities at 60 sites distributed among four rivers. Based on Principle Component Analysis of physical habitat data collected concomitantly with the algal data, sites were separated into those with a mean thalweg depth of >4 m (deep sites) or < 4 m (shallow sites). Three of the methods targeted periphyton and one phytoplankton. Among the periphyton methods, two were quantitative (one targeted specific habitats and the other was systematically random), and one was a qualitative multi-habitat method. The phytoplankton method was composed of a single composited depth and width integrated sample. We examined diatom richness and composition metrics, most of which are included or proposed by the Commonwealth of Kentucky for use in the Diatom Bioassessment Index. All methods collected sufficient numbers of diatom taxa, but metic sensitivity to stressors varied by site dept and collection method. The phytoplankton method collected smaller percentages of eutraphentic and motile diatoms than other methods, but had higher correlations for stressors. This was true especially for water chemistry related stressors. Periphyton data had a mixed response, but overall performed better at the shallower sites, especially for riparian-based stressors. However, the ability of metrics to detect stressors was not consistent among the three periphyton methods tested. At shallow sites, the quantitative targeted-habitat periphyton method collected significantly fewer diatoms than the other periphyton methods, but it was significantly correlated with more stressors.