REVIEW OF A 17-YEAR CHLOROPHYLL RECORD AS IT PERTAINS TO THE TROPHIC STATUS OF LAKE-OKEECHOBEE, FLORIDA, USA

A 17-year record of chlorophyll alpha at eight limnetic sampling stati ons was used to evaluate putative changes in the trophic status of Lak e Okeechobee, a shallow polymictic lake located in the subtropical env ironment of South Florida. Significant spatial differences were observ ed in the temporal patterns and variability of chlorophyll alpha conce ntrations. The highest chlorophyll alpha values were found in the nort hern and northwestern regions of the lake. The center of the lake, sub ject to high levels of non-algal suspended solids, exhibited relativel y low chlorophyll alpha values and coefficient of variation. The lowes t chlorophyll alpha values were observed at the southernmost sampling station in the lake. This was also the station that showed a significa nt upward trend in annual mean chlorophyll alpha values over the 17-ye ar period of record. Examination of the relationship between chlorophy ll alpha and three key environmental variables (i.e., total phosphorus concentration, phosphorus loading, and lake stage) revealed significa nt correlations at two out of the eight stations. The overall results of this study indicate that spatial and temporal disparities in the di stribution and dynamics of chlorophyll alpha in Lake Okeechobee mandat e more temporally and spatially intense approaches to the evaluation o f trophic state than used in previous studies.