Factors influencing periphyton growth in agricultural streams of central Illinois |
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Authors: | M. D. Munn L. L. Osborne M. J. Wiley |
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Affiliation: | (1) Illinois Natural History Survey, Aquatic Biology Section, 607 E. Peabody Dr., 61820 Champaign, IL, U.S.A.;(2) Present address: School of Natural Resources, University of Michigan, 48109 Ann Arbor, MI, U.S.A. |
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Abstract: | Factors limiting periphyton accrual in east-central Illinois agricultural streams were investigated. Nutrient-diffusing substrata were used to examine periphyton macronutrient limitation in streams in two agricultural watersheds. Substrata consisted of sand-agar mixtures with one of six experimental treatments. Macronutrients included carbon, nitrate, phosphate and combinations of the three. Substrata were collected after a 5 and 9 day period and analyzed for chlorophyll a. None of the treatments were significantly greater than the controls at any of the seven stations, thus we conclude that periphyton in these streams was not nutrient limited. Highest periphyton colonization/growth rates were associated with the smaller upstream reaches, while lower rates occurred in the larger downstream reaches. Multiple regression showed that most of the variance in the rate of chlorophyll a accrual after five days was explained through water temperature and turbidity (r2 = 0.91); whereas, stream nitrate and phosphate concentrations accounted for no significant portion of the variance. We conclude that instream primary production in agricultural streams of central Illinois is limited by temperature and light. |
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Keywords: | carbon Illinois light nitrate nutrient limitation periphyton phosphate streams temperature |
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