The Role of Zooplankton in Water Clarification and Purification in a Polluted Highly Eutrophic Fish Pond

A high turbidity of water is observed in a fish pond with a high content of organic matter. Because of this, phytoplankton develops poorly. Daphnia longispina predominated among zooplankton, consuming small-sized detritus, bacteria, and other suspended organic matter. Daphnia was located in the upper part of the reservoir. The fish in the studied pond were large and lived mainly near the bottom. Accordingly, their trophic impact on zooplankton was low. Clarification of water in the upper layers of the pond occurs due to the high filtration activity of Daphnia.