Incidence of microcystin-producing cyanobacteria in Lake Tana, the largest waterbody in Ethiopia

摘要

The occurrence of toxic cyanobacterial blooms is a serious problem for fast-developing countries in Africa, such as Ethiopia, that are struggling with significant degradation of the natural environment and limited access to water of good quality. Research undertaken on Lake Tana in Ethiopia between 2009 and 2011 was intended to assess the seasonal threat from cyanobacteria and to select methods for tracking of this threat in the future. The cyanobacterial genus Microcystis was found to be present throughout the monitoring period, and M.aeruginosa was determined as the dominant species. Moreover, in all samples, toxigenic cyanobacteria with the potential to produce microcystins were detected. High levels of microcystins, ranging from 0.58 to 2.65gL(-1), were detected each November, which indicates that in the postrainy season, water usage should be limited. The correlation between concentrations of chlorophyll-a and microcystins suggested that chlorophyll-a could be used as an indicator of the potential presence of cyanobacterial-derived hepatotoxins in Lake Tana in the future. Furthermore, for quick quantitative confirmation of the presence of microcystins, a simple and rapid ELISA test was recommended.