THE EFFECT OF WATER-FLOW RATE ON ZOOPLANKTON AND ITS ROLE IN PHOSPHORUS CYCLING IN SMALL IMPOUNDMENTS

The attempt was made to determine the effect of water flow rate on zoo plankton density, trophic structure and the role of phosphorus regener ation by zooplankton in phosphorus sedimentation in four impoundments with a water exchange from less than 10 hours to 8-12 days. Formation of stagnant environments together with the increasing time of water ex change in impoundments created good conditions for development of zoop lankton communities. As a result, the rate of phosphorus regeneration was higher and the turnover time of the total and seston phosphorus wa s shorter in impoundments than in streams above impoundments. A hypoth esis that the stations with a long time of water exchange could be a k ind of a trap for nutrients excluded from cycling in running waters is validated.