DECLINE IN TOTAL PHOSPHORUS IN THE SURFACE WATERS OF LAKES DURING SUMMER STRATIFICATION, AND ITS RELATIONSHIP TO SIZE DISTRIBUTION OF PARTICLES AND SEDIMENTATION

The decline in total phosphorus (TP) in the surface waters of 40 oligotrophic to mesotrophic lakes during stratification varied from 0 to 59.0%. Sediment traps were deployed in four of the lakes to examine the relationship between decline in TP and sedimentation. Declines in TP and sedimentation of P were similar in magnitude when summed over the stratified season, and a positive correlation between TP decline and sedimentation rate was observed. Lakes possessing larger particles exhibited larger declines in particulate phosphorus (PP) than lakes with smaller plankton. Declines in TP were not significantly related to particle size, possibly because of the influence of spring concentrations of dissolved P, which quickly declined in all lakes in which they were observed. These results support the contention that sedimentation plays a major role in the decline in TP during stratification and that sedimentation is influenced by plankton community structure.