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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Periphyton
PREDICTING PERIPHYTON BIOMASS IN WESTERN UNITED STATES REFERENCE STREAMS.
S.L. Rollins1, R.J. Stevenson1, and C.P. Hawkins2. 1Department of Zoology, Michigan State University, East Lansing, Michigan, USA 48824-1115, 2Department of Fisheries and Wildlife, Utah State University, Logan, Utah, USA 84322-5210
Predictive models were developed to determine environmental factors influencing benthic algal production in streams throughout the western United States. Micro- and macro-algal biomasses were assessed in the field independently using a rapid periphyton survey method, which allowed for separate analysis of the two. The following variables were evaluated for 225 minimally impacted streams: mid-channel canopy cover, alkalinity, conductivity, reach slope, elevation, latitude, longitude, mean substrate size, depth, mean wetted width, and a number of watershed evaluations. Longitude was an important predictor of microalgal biomass, with streams in the Pacific Northwest having significantly higher growth than the rest of the region. However, variation in macroalgal biomass was largely attributed to percent mid-channel canopy cover. The probability of finding macroalgal growth on substrata decreased significantly when canopy cover exceeded 73.5%. Mean wetted width, alkalinity, and elevation were also important predictors for macroalgae. These data suggest that different environmental factors influence lotic micro- and macro-algal production. Separate measures of these two components of periphyton biomass could lead to important insights regarding the influence of community structure on benthic primary production.
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