Phosphorus Uptake Dynamics as Related to Mathematical Modeling of Cladophora at a Site on Lake Huron

Cladophora is a significant symptom of eutrophication in Lakes Erie and Ontario and is a local problem associated with nutrient perturbations in Lakes Huron, Michigan, and Superior. This paper presents results of measurements of phosphorus uptake rates as a function of internal phosphorus levels by Cladophora growing near Harbor Beach, Michigan. Cladophora collected near the Harbor Beach wastewater treatment plant had high levels of internal phosphorus and low (or even negative) phosphorus uptake rates. Cladophora distant from the wastewater treatment plant had low internal phosphorus levels and rapid phosphorus uptake rates. The experimental results are discussed in terms of quantitative kinetic formulations which may be incorporated into mathematical models useful for predicting the response of Cladophora to alternative management and control strategies. Preliminary model simulations of Cladophora biomass, internal phosphorus, and external phosphorus are qualitatively similar to observed field data.