This research project consists of four interrelated project areas utilizing field manipulations and laboratory experiments designed to elucidate several features of epipelic periphyton function in lake ecosystems. Specific objectives are 1) to determine how widespread are diel fluctuations in phosphorus efflux rates from sediments among different lake types, 2) to further define the mechanism(s) controlling diel variation in phosphorus efflux 3) to quantify the effects of hydrodynamics and epipelic algal photosynthesis on seasonal oxygen dynamics of lake hypolimnia, and 4) to quantify the relative contributions of epipelic periphyton production and seston sedimentation to annual sediment accretion. The mechanistic approach to examining these process- level questions will rely on extensive use of oxygen and pH sensitive microelectrodes in both field and laboratory, and on radiotracers for laboratory studies of biogeochemical processes affected by the metabolic activity of periphyton. The research will be based at The University of Notre Dame Environmental Research Center in northern Wisconsin.
