Environmental studies on phytoplankton diversity in drainage water of main drains in Eastern Delta, case study

Abstract

In order to monitor the ecological status of the largest Egyptian northern drains, an environmental comparison is performed between Bahr El Baqar Drain and Hadous Drain based on water quality and the community composition of their phytoplankton groups to assess the environmental hazard impacts on Lake Manzala. From both drains during the period 2015–2020 (5 years average), fourteen parameters were seasonally recorded; Hydrogen Ion, biological oxygen demand, chemical oxygen demand, electric conductivity, total suspended solids, total dissolved solids, bicarbonates, cations and anions (nitrates, sulfates, Calcium, Sodium, Potassium, Magnesium and Chloride), as well as seven heavy metal parameters (Copper, Iron, Manganese, Nickel, Lead, Boron, and Zinc). Statistically, phytoplankton seasonal dominance and abundance, diversity indices, species richness, evenness, Shannon and Simpson indices, and Pearson correlation were statistically calculated. The results showed that the average values of pH, HCO₃, BOD, COD, EC, TSS, TDS, NO₃, anions and cations in Bahr El Baqar Drain were higher than those in Hadous Drain. Phytoplankton groups in both drains belonged to five major groups with a descending order of dominance; Cyanophyta > Chlorophyta > Bacillariophyta > Euglenophyta > Dinophyta. Bicarbonates positively correlated with Chlorophyceae (evenness = 0.871, Shannon = 2.029), Cyanophyceae (1.964, 0.853), Euglenophycea (0.857, 1.535), and Dinophyceae (0.836, 0.918). BOD and COD positively correlated with Nitzschia sp., Euglena velata, and Peridinium volzii, and negatively correlated with Amphora sp., Euglena viridis, and Ceratium hirundinella. Chlorophyceae correlated positively with K, Mg, Cl, SO₄ and NO₃. Cyanophyceae correlated negatively with K, Mg, Na, B, Cl and SO₄. Bacillariophycea positively correlated with Ni and NO₃. Dinophyceae negatively correlated with Cl and SO₄. Phytoplankton species expressed different dominance, diversity indices and statistical correlation with each water quality parameter, which reflected the selectivity and growth manners of algae. From the former mentioned results, it was concluded that the phytoplankton groups are very sensitive and useful indicator of the health status of any water stream. Concerning the bad quality of water in Bahr El Baqar Drain and Hadous Drain, management plan should be implemented for both drains, in particularly Bahr El Baqar Drain, to preserve the environmental status of Lake Manzala.