ECOLOGICAL STUDIES ON ZOOPLANKTON COMMUNITIES WITH PARTICULAR REFERENCE TO FREE LIVING PROTOZOANS AT RIVER NILE­ DAMIETTA BRANCH

Abstract

The present study is an attempt to provide recent information on some biological components of the ecosystem in River Nile- Damietta Branch, specially the free-living protozoa Six stations were chosen along Damietta Branch representing different conditions and human activities on the river. Four main groups of protozooplankton community were recorded during the present study namely, Rotifera, Copepoda, Protozoa and Cladocera • 19• . Protozoan species were recorded for the first time in the Nile in Egypt during the present study. The seasonal variation of the total zooplankton showed two peaks during the period of study one in May and other in February. Abundance and distribution of the Nile protozooplankton were found to be affected by both biotic and abiotic factors. Along the area of study Talkha was poor in protozooplankton density in all months of the study, while Faraskour was found to suffer from eutrophic conditions due to stagnation of its water as a result of the complete closure of the Faraskour Dam gates. Finally we concluded that Damietta Branch of the Nile is eutrophic productive water body, which needs a plan•: to improve its conditions, since the complete closure of the Damietta Branch seems to exert harmful effect. So, the opening ofFaraskour Dam from time to time in regular way will help in improving the conditions at this branch of the Nile. Controlling the amount of the supplementary food added to the river in the area of fish culture, since the excess food harm the water quality of the river leading to high eutrophication.