Toxicity and toxin composition of Microcystis aeruginosa from Wangsong reservoir

Abstract

Objective: The increasing world population, resulting in increased anthropogenic water pollution, is negatively impacting the limited available water resources. In South Korea, this similarly affects the water quality of reservoirs. As water is a basic necessity for life, water quality monitoring is essential but typically does not include toxicity testing. However, as toxic bloom event frequencies are increasing, this previously neglected aspect becomes pertinent. Therefore, in the present study, the toxin composition and toxicity of a Microcystis aeruginosa strain isolated from a persistent bloom in lake Wangsong, South Korea, was investigated. Methods: A combination of bioassays and chemical analysis was used for this purpose. The bioassay species included terrestrial and aquatic plants, an alga, a rotifer, a tubificid annelid, and crustaceans, representing various trophic levels. Results: The strain was found to produce microcystin-LR, -RR, and YR, as well as β-N-methylamino-L-alanine. The bioassays indicated that the primary producers were less sensitive to the crude extract. Conclusion: The presence or absence of a visible cyanobacterial bloom is also not an indication of the toxins that may be present in the afflicted waters, and thus does not predict exposure risk. Similarly, the presence and absence of toxins and mixtures thereof does not indicate the ecological effect. Therefore, it would be advantages to include toxicity testing into routine water testing regimes to better understand the impact of harmful algal blooms.