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Title: Direct and indirect influences of aquatic macrophyte communities on phosphorus mobilization from littoral sediments of an inlet region in Lake Delavan, Wisconsin
Authors: Geological Survey (U.S.)
Wisconsin. Department of Natural Resources
United States. Army. Corps of Engineers. St. Paul District
Water Operations Technical Support Program (U.S.)
James, William F., Aquatic biologist
Smith, Craig S., Biologist
Barko, John W.
Field, Stephen
Keywords: Aquatic macrophytes
Internal loading
Lake Delavan
Littoral zone
Phosphorus budget
Sediment phosphorus
Water quality
Littoral drift
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: Direct and indirect influences of aquatic macrophytes on phosphorus (P) mobilization from littoral sediments of the inlet region of Lake Delavan, Wisconsin, were examined. Macrophyte species composition, biomass, and P content were evaluated at the approximate peak in biomass to estimate the macrophyte P pool. Submersed macrophytes occupied over 50 percent of the inlet surface area and contained about 600 kg of P, most of which was derived presumably from the inlet sediments via root uptake. Rates of P release from sediments of the inlet region were examined in the laboratory under different redox and pH regimes using sediment systems and also in situ using sediment peepers. In the laboratory, rates of P release from sediments increased about twofold (i.e., to 7 mg m⁻² d⁻¹) under oxic conditions as a result of adjusting the pH of the overlying water from 8.5 to about 9.0. Laboratory rates increased to a maximum of 23 mg m⁻² d⁻¹ under anoxic conditions. Both pH and dissolved oxygen (DO) in the inlet region exhibited marked seasonal fluctuations, as a result of community metabolism. Using continuous records of pH and DO in the inlet region and ranges in rates of P release measured in the laboratory, an overall mean rate of P release of 5.7 mg m⁻² d⁻¹ from the littoral sediments was estimated during the summer (April-September) of 1994. Rates of P release estimated from Fickean diffusional fluxes were similar to rates estimated from pH and DO. Results suggest that the aquatic macrophyte community of the inlet region of Lake Delavan plays an important role in the P budget of this system.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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