Biochemical profile of phytoplankton and its nutritional aspects in some khors of Lake Nasser, Egypt

•The quantitative and qualitative phytoplankton biochemical contents were carried out seasonally at the selected Khors.•Cyanophyceae was the most dominant group at the studied khors.•Protein represents the main biochemical content, which reflects a healthy phytoplankton with high relative growth rates.•Winter was the optimum season for the measured biochemical contents; concurrently with high nitrate value.•High significant variation (p ≤ 0.05) was found between the four khors according to the studied phytoplankton biochemical parameters during winter.

Lake Nasser has a numerous side extensions known as khors. Four khors were selected, two at the northern region (Kalabsha and Wadi-Abyad) and the others at southern (Tushka and Korosko). Seasonal study was carried out to estimate the quantitative and qualitative phytoplankton biochemical contents at the studied khors. Cyanophyceae was the most dominant group at the studied khors, where Microcystis aeruginosa, Microcystis flos-aquae, Lyngbya limnetica, Microcystis wesenbergii and Merismopedia glauca were the most dominant species. Protein represents the main biochemical content of phytoplankton at the khors, which generally reflects a physiologically healthy phytoplankton with high relative growth rates. Khor Korosko recorded the highest nutritive characters of phytoplankton proteins, carbohydrates and lipids (6.6 g/l, 14.2 and 4.45 mg/l), contrary to chlorophyll a which attained the least value of 71.4 mg/l. Winter was the optimum season for the measured biochemical contents; concurrently with high nitrate value. Flourishing of Copepoda and Cladocera in winter and highly fish muscle contents of protein and lipid at the same time may be attributed to the elevation of the biochemical contents of microalgae. High significant variation (p ≤ 0.05) was found between the four khors according to the studied phytoplankton biochemical parameters during winter.