Effect of Nile River water quality on algal distribution at Cairo, Egypt

Abstract

Changes of phytoplankton density and their relation to physicochemical characteristics along the Nile River have been noted in the Cairo district between 1976 and 1982. Three major phytoplankton groups were found to dominate the river Nile: green algae, blue-green algae, and diatoms. Diatoms represent the most dominant group and comprised from 42% to 96% of the phytoplankton community during the investigated period. Blue-green algae comprised from 0.7% to 48% of total cell number. Green algae represent the low percentage group, which ranges from 0.2% to 41% of Nile water algae. High species diversity ( H′) was detected in green algae (1.22) followed by diatoms (0.84); the lowest diversity was in blue-green algae (0.45). The density of total phytoplankton count fluctuated between 10 6 and 10 7 organism/L. The concentration of chlorophyll- a ranged from 5 to 37 mg/m 3. Primary production rates in the Nile River ranged from 8.5 to 52 mg O 2/m 3h. Statistical analysis revealed significant positive correlations between chlorophyll- a content, and concentrations of phosphoruss and nitrate. Phytoplankton diversity, primary production, ammonia, and nitrite content revealed that there is no indication of pollution in the Nile.