Distribution of Zooplankton Community in the River Nile at Esna Barrages, Egypt in relation to some ecological factors

Abstract

In riverine systems, zooplankton communities are usually thought to be driven by abiotic forces. This study was designed to assess the effect of ecological factors on the distribution of zooplankton community in the River Nile at Esna barrages which located 1.2 km downstream the old barrages. Monthly samples were collected during a period of one year from six sites situated in the River Nile, (upstream and downstream) of Esna Barrages. Seven physic-chemical parameters were measured during sampling using electronic portable instruments: air and water temperature, hydrogen ion concentration, dissolved oxygen, conductivity, total dissolved solids and turbidity. The collected zooplankton groups were Cladocera, Copepoda and Ostracoda where Cladocera exhibited the highest peak of density. The highest value of total abundance of zooplankton was recorded during winter 40% and the lowest value was recorded during summer 11%. The results indicated that Turbidity, pH and conductivity were the most affecting factors on abundance of all zooplankton groups during the study. Cladocera group correlated significantly with dissolved oxygen (p>0.01) and pH (p<0.01). Moreover, temperature and turbidity were the most affecting factors on Copepoda, while Ostracoda was affected by pH and conductivity.