PHOSPHORUS DEFICIENCY AND ITS VARIATION AMONG LAKES

The rate constant of orthophosphate uptake (k1), a measure of orthophosphate demand:supply, proved to be only weakly related to watershed area and to the total phosphorus (P) concentration of the water (R2=0.210). Abundance of the biota and other aspects of water chemistry were all unrelated to the intensity of P-deficiency as it varies among lakes. In contrast, within-lake seasonal variability of the rate constant of orthophosphate turnover (kt, which is approximately equal to k1) is strongly related to temperature and bacterial abundance (R2 = 0.575 to 0.828). The results indicate that the seasonal variation in phosphorus deficiency depends strongly on bacterioplankton activity, whereas inter-lake variability in phosphorus deficiency is determined mainly by factors other than morphometry, plankton abundance, or trophic richness. -from Author