Changes in the physicochemical and biological characteristics in the lentic and lotic waters of the Nile river

This study aims to compare the changes in the physicochemical and biological characteristics simultaneously in Nasser Lake as lentic water and the main Nile River as lotic water due to the construction of the Aswan High Dam. Therefore, water samples were seasonally collected from four sites along the lentic water and five sites along the lotic water. The results showed an increase in the water temperature and pH in the lentic than the lotic waters, while TSS, nutrients, BOD, and TDS showed a reverse trend. Furthermore, zooplankton recorded 45 taxa; 31 rotifers, 7 cladocerans, and 3 copepods, in addition to 4 taxa represented in rare groups. Rotifera dominated the main river water, while Copepoda dominated Nasser Lake water. Twenty-two holozooplankters appeared only in the main river water, while three holozooplankters appeared in the lake water and 20 holozooplankters were shared in both waterbodies. The appearance of Ptygura libera in the river for the first time proved that the lake is the source of some zooplankters in the river. According to the trophic state index and the river pollution index calculations, the two waterbodies categorized as eutrophic and unpolluted, respectively.