Toxicologie environnementale et analytique

Assessment of Cyanobactrial Blooms Associated with Water Quality Status of Lake Chamo, South Ethiopia

Abstract

Adane D Fenta and Almaz A Kidanemariam

Cyanobacterial blooms are group of phytoplankton called blue green algal blooms which are occurred commonly and naturally in many aquatic systems. In this paper, assessment of groups of different phytoplankton community and physicochemical water quality properties (pH, DO, TDS, temperature, total hardness, chloride, Chlorophyll a, nutrient level of PO4 3--P, NO3-N, NO2 --N, TP, TN) were analyzed and discussed using both original and literature data from the lake Chamo-known by its fish potential and fresh water in Ethiopia. Samples of water were taken from three different sites within the lake (from Inlet, Center and out let sites) during the dry season of 2014/15. Average Physicochemical properties of lake water were determined for each of the sites and cyanobacterial algae bloom was assessed by taking the composite sample of water biologically. The overall water quality parameters and phytoplankton biomass results have been observed as Turbidity (7.10-20.42 NTU), a maximum pH 9.02, TDS (622-651 mg/l), electric conductivity (720- 782 μS/cm), DO (10.26-17.61 mg/l), nitrate-nitrogen (3.12-5.35 mg/l), nitrite-nitrogen (0.03-0.11 mg/l), Total nitrogen (3.18-5.39 mg/l), phosphate (1.08-1.47 mg/l), Total phosphorus (0.43-0.55 mg/l), Chlorophyll a (23.85-28.87 μg/l) and total of 54 species from 9 classes of phytoplankton, dominated by large colonial forms of Microcystis and Anabaena species. The values of the whole analyzed parameters have shown significant variation in site (P<0.05). Finally, these results were compared with previous studies and concluded that the lake is getting worse and worst time to time and needs better follow up to protect and make it suitable for multiple purposes.