A B S T R A C TLake 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.

This study was conducted to evaluate the impact of human activities on the ecological health and food chain at the shores of four Nile Islands in Great Cairo including El-Qeratten, El-Waraq, El-Zamalek, and El-Manial. Water quality, bacteria, phytoplankton, benthic algae, zooplankton, macrobenthic invertebrates, and bony fishes were examined at each island shore over two seasons including the lowest and the highest flow (February and July 2020, respectively). The obtained results showed that the average values of most of the chemicals in Nile Island’s water were within the Egyptian water quality limits. Discriminant analysis of physicochemical factors revealed a similarity between El-Waraq and El-Qerateen and between El-Manial and El-Zamalek. El-Qeratten was the most polluted island. It has the highest total and fecal coliform bacteria count (3.155 and 3.050 Log MPN/100 mL, respectively). El-Zamalek shores have the highest phytoplankton (33,582 cells × 104 L−1) and zooplankton count (310,891 organisms × m−3) and phyto-biochemical values. Biochemical analysis of phytoplankton demonstrated the richness of the bulk by protein (> 85% of biomass), indicating that phytoplankton has a high nutritional value. Elevated zooplankton count was recorded at El-Zamalek, which coincided with the peak of phytoplankton abundance. Mollusca were the dominant macrobenthic invertebrates on most of the island’s shores. Bony fishes were represented by 27 species and two crustaceans. The levels of the metals in fish samples were compared with the food safety guideline endorsed by the World Health Organization and Food and Agriculture Organization (WHO/FAO) to evaluate the toxicity level.

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B URULLUS Lagoon, also known as Lake Burullus, is a brackish water lake in the Nile Delta in Egypt. In this study, changes in environmental conditions were assumed to affect phytoplankton species composition and their biochemical structure. The biochemical content of phytoplankton in Lake Burullus was preliminarily explored. Winter cruises were compared with summer cruises from 12 sites representing the main eastern, middle, and western lake basins in 2018. Results revealed that phytoplankton exhibited seasonal variations. In particular, it attained the lowest value in winter (72300 units/L) and the highest value in summer (88700 units/L). This observation was consistent with the high total protein content (2692.5mg/L) in summer. The first major class was Chlorophyceae (37.9%) followed by Bacillariophyceae (29.31%) and Cyanophyceae (20.7%). By comparison, Euglenophyceae and Dinophyceae were rare classes constituting 8.63% and 3.4%, respectively. The maximum total biochemical contents were found in the middle of the lake in winter (870.5, 57.6, and 6.1 mg/L of proteins, carbohydrates, and lipids, respectively), indicating the increase in the total density of phytoplankton, especially Chlorophyceae (13700 units/L), in the central basin (29200 units/L). The optimum total biochemical structure was obtained in the western basin in summer (1909.1, 55.4, and 6.5mg/L of proteins, carbohydrates, and lipids, respectively), suggesting that the phytoplankton density increased to 56000 units/L. Q index showed that the middle and western basins were in mesotrophic to eutrophic states. These findings demonstrated that excessive nutrient loads of drainage water into Burullus Lagoon significantly affected the phytoplankton biodiversity. Therefore, highly efficient management strategies must be developed and implemented in Burullus Lagoon.