Factors determining the distributions of total phosphorus, total nitrogen, and chlorophyll a in Florida lakes

Abstract

Using data from 1387 lakes collected over 3 decades, we found a wide range in the concentrations of total phosphorus (TP), total nitrogen (TN) and chlorophyll (Chl-a) in Florida lakes, and that edaphic factors as outlined by the United States Environmental Protection Agency's Florida Lake Regions were dominant in determining the concentrations of plant nutrients in the state's lakes. The hypothesis that the majority of the eutrophic lakes in Florida without known point source pollution are the result of nonpoint source nutrient pollution was tested in several ways and rejected. There was no correlation between the Landscape Development Intensity index and the concentrations of TP, TN, and Chl-a examined in Florida lakes. Several of Florida's 30 benchmark lakes (lakes with minimal human impact and meeting designated uses) were eutrophic, and there was no significant difference between the mean concentrations of TP and TN in these lakes versus all remaining Florida lakes. Paleolimnological studies also showed that several lakes were eutrophic to hypereutrophic prior to 1900, a time before significant population growth in the State of Florida. To help develop numeric nutrient criteria for Florida lakes that take regional differences into account, we grouped similar lakes into 6 TP zones and 5 TN zones. [Supplemental materials are available for this article. Go to the publisher's online edition of Lake and Reservoir Management to view the supplemental file.]