Utilization of phytoplankton distribution and water quality criteria for the environmental assessment: A case study on Lake Manzala, Egypt

Aim Lake Manzala is a dynamic ecosystem, receiving enormous pollutants and wastewater that pose serious environmental threats and risks. Using integrated methods for environmental assessment in Lake Manzala, as an applied model, is what the current study aspires to achieve. Methods Sampling was carried out via 8 stations, covering the entire Lake during November 2022. Phytoplankton distribution and water quality index (WQI) were investigated. Results and conclusions A total of 60 phytoplankton taxa, belonging to five classes were obtained. Bacillariophyceae was the most productive (27 sp.) and predominated by Nitzschia. Cyanophyceae. Chlorophyceae, Dinophyceae and Euglenophyceae were detected and represented by 13, 8, 7 and 5 sp., respectively. A strong positive correlation between Chl. a content and the total count of phytoplankton was observed at the majority of stations. Water quality variables showed correlations, both positive and negative, with the distribution of phytoplankton. The water quality index showed extreme values ranging between 829.18 and 315, 37 at stations 2 and 7, respectively, as we go ahead towards the drains, the more we detected a higher WQI value. The water quality index (WQI) showed a confirmed highly significant correlation with the dominance and prosperity of the given classes of phytoplankton, as well as most of their corresponding species. This provides an integrated view for the environmental assessment of the water body, by highlighting the sources of pollution and the affected stations. This was reflected in the assessment of Lake Manzala, by indicating the need for extensive monitoring and taking urgent measures related to drainage water treatment.