Diversity of euglenoids in a drinking water source in Burkina Faso (West Africa): implications for sustainability and water quality

Euglenophyta are a group of algae that occur in water polluted by organic matter, which makes them a good indicator for organic pollution. This study aimed to determine the diversity of Euglenophyta, the environmental conditions favourable to their development and their implication in the sustainability and quality of the water in Loumbila reservoir. Algal and chemical water samples were collected monthly between January 2015 and June 2015. Phytoplankton species were identified under a light microscope using a Fuchs-Rosenthal chamber for algal cell counting. In total, 34 species of Euglenophyta were identified, four of which are new to the algal flora of Burkina Faso. The abundance and number of species of the genera Euglena and Phacus were significantly (p < 0.05) higher in the dry season. Euglena deses, Euglena texta, Euglena caudata, Phacus lefevrei, Phacus ranula and Phacus orbicularis were identified as indicator species of high nutrient concentration. The abundance of these genera was positively correlated with pH, dissolved oxygen, water transparency, conductivity, nitrates and orthophosphates. This study on the diversity of Euglenophyta enabled us to identify indicator species of reservoir pollution and the environmental factors favourable to their development. This can be used to guide the future water quality monitoring and management of the reservoir.