Wind Control of Algae Growth in Eutrophic Lakes

In eutrophic lakes, light and turbulent mixing near the water surface often controls the actual occurrence and disappearance of algal blooms. While nutrients provide necessary materials for a high growth potential, light and mixing provide energetic controls. An expression for an equilibrium phytoplankton concentration supportable under given physical conditions is provided. Loss of phytoplankton mass, e.g., by respiration or grazing, is included. For illustrations, time variable phytoplankton concentrations are computed on a daily timescale and as a function of insolation, mixed layer depth for a very eutrophic lake from April-October with a constant set of coefficients for the whole season. The length of the growth season, time variable phytoplankton concentrations in the mixed layer, and other features of the biomass are well predicted. Daily mixed layer depths are computed for input from weather and lake morphological data.