Relationships of Annual ChlorophyllaMeans, Maxima, and Algal Bloom Frequencies in a Shallow Eutrophic Lake (Lake Okeechobee, Florida, USA)

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Abstract
Fifteen years of historical data from Lake Okeechobee, Florida, were used to quantify relationships between annual mean and extreme values of algal biomass, measured as chlorophyll a Yearly chlorophyll a maxima and algal bloom frequencies (the percent of samples during a year containing >40 μg L−1 chlorophyll a) increased approximately 2-fold for each unit increase in the annual chlorophyll a mean, although there was some variation in these relationships among different regions of the lake. Threshold chlorophyll a concentrations (15–21 μg L−1) were also identified, below which bloom frequencies were reduced to near zero. Results indicate that if nutrient diversion strategies are successful in reducing annual mean chlorophyll a concentrations in Lake Okeechobee, even more pronounced reductions in algal blooms will occur. Reductions of lake-wide chlorophyll a means to early 1980s levels might nearly eliminate algal blooms as defined here.