RELATIONSHIPS BETWEEN LIGHT AVAILABILITY, CHLOROPHYLL-A, AND TRIPTON IN A LARGE, SHALLOW SUBTROPICAL LAKE

The relationships between planktonic chlorophyll a and mean light avai lability in the mixed layer were examined for Lake Okeechobee, a shall ow eutrophic lake in south-central Florida. There were significant spa tial differences in the nature of this relationship. In the northern a nd central regions of the lake, concentrations of nonalgal suspended s olids, tripton, were high due to muddy sediments and polymictic condit ions. Light attenuation was predominantly correlated to the concentrat ion of tripton and chlorophyll a concentrations were positively correl ated to mean light availability in the mixed layer, I-m. The western a nd southern regions of the lake had lower concentrations of tripton an d light attenuation was correlated to chlorophyll a concentrations in summer and fall. Variables which estimate mean light availability in t he mixed layer, such as I-m, may provide insight into the role of ligh t availability in the control of phytoplankton standing crop.