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Distribution of benthic algae in the upper Illinois River basin in relation to geology and land use
Author(s) -
Leland Harry V.,
Porter Stephen D.
Publication year - 2000
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1046/j.1365-2427.2000.00536.x
Subject(s) - eutrophication , benthic zone , detrended correspondence analysis , canonical correspondence analysis , ecology , environmental science , drainage basin , structural basin , nutrient , salinity , algae , hydrology (agriculture) , ordination , habitat , biology , geology , geography , cartography , geotechnical engineering , paleontology
SUMMARY1 Benthic‐algal distributions in the upper Illinois River basin, IL, U.S.A., were examined in relation to geology, land use, water chemistry and stream habitat using (detrended) (canonical) correspondence analysis, autecological metrics and indicator‐species analysis in order to identify the major environmental gradients influencing community variation. 2 Ionic composition and major nutrient [i.e. nitrogen (N) and phosphorus (P)] concentration of surface waters, salinity (Na‐Cl type), substratum type and physiognomic form of dominant species were primary factors contributing to variation in benthic‐algal assemblages of the basin. Basin geology was a significant contributing factor, but the explained variance associated with this factor was less than that related to land use. 3 Proportions of algal biomass consisting of cyanophytes, filamentous chlorophytes, halophilic diatoms and diatoms which utilize nitrogen heterotrophically were greater in eutrophic river segments than in less nutrient‐enriched segments. Composition of the benthic flora indicated meso‐eutrophic or eutrophic conditions throughout the basin; there were few diatoms indicative of hypertrophic waters. Shifts in diatom‐assemblage structure in response to nutrient loading provided an incomplete representation of the community‐response curve. 4 A weighted‐averages regression model based on total P and benthic‐algal abundances (all divisions included) yielded a highly significant correlation ( r 2 = 0.83) between species‐inferred [WA (tol) ] and observed total P, with systematic bias (increased deviation of residuals) occurring only at concentrations greater than ∼ 1.0 mg L −1 total P. This result indicates that total P regression and calibration models can be predictable for a river basin receiving excessive loadings of phosphorus.