The study compared changes in water quality and organisms in Nasser Lake and the Nile River after the Aswan High Dam was built. Nasser Lake had warmer and more alkaline water, while the Nile River had higher levels of pollutants. Different types of tiny animals called zooplankton were found in each water body, with more rotifers in the river and more copepods in the lake. Some zooplankton species were only in the river, suggesting they came from the lake. Both water bodies were found to be eutrophic, but the river was less polluted than the lake.