Plankton and Zoobenthos in the Southern Region of the Nile in Egypt: Community Structure, Relative Abundance and Diversity

Major biological parameters along with nutrient concentrations of the Nile in Upper Egypt were analyzed during 2007 for a better understanding of community structure and diversity of the main functional groups of organisms. The abundance of plankton and zoobenthos was followed seasonally. Altogether 168 taxa (85 phytoplankton, 43 zooplankton and 40 zoobenthos) were encountered from the Nile in Upper Egypt. The combined contribution of chironomid larvae, Mollusca and Oligochaetae represented the abundant groups of the Nile zoobenthos throughout the study period. The results of this study suggested that the sediment contents of organic matter and CaCO3, as well as water temperature and NO3-N concentrations, seemed to be important in determining the abundance and biomass of zoobenthos. Most importantly, the results of this study will provide valuable information for river management. Simultaneously; alpha, beta, gamma and Shannon (H̀) diversities of these communities were measured. Alpha and gamma diversities for phytoplankton were higher than those of zooplankton or zoobenthos. Shannon diversity index for the different groups was relatively low due to the less water retention of the lotic ecosystem. The composition similarity of the investigated samples and the weak rate of species displacement among sites were reflected by β diversity.