PHOSPHORUS DEFICIENCY DIAGNOSTICS IN THE EUTROPHIC RIMOV RESERVOIR

In order to assess the occurrence and the degree of phosphorus deficie ncy, the upper layer (0-2 m) of the eutrophic Rimov Reservoir (Czechos lovakia) was sampled from March to October 1990 in one- to three-week intervals. Soluble reactive phosphorus and maximum possible orthophosp hate (by Rigler's radiobioassay) concentrations, seston elemental stoi chiometry (C/P; N/P), orthophosphate turnover time, and phosphorus def iciency index (= ratio of the primary production to the Vmax of the PO 4 uptake) were estimated. Early in spring, during the spring clear-wat er period, and in the autumn, no indications of P-deficiency were foun d. Strong P-deficiency was detected in summer (June - September), mode rate to strong deficiency also during the spring phytoplankton maximum . The concentration of SRP < 5 mug.l-1 indicates phosphorus deficiency in the Rimov reservoir.