Temporal dynamics of intra-and extra-cellular microcystins concentrations in Koka reservoir (Ethiopia): Implications for public health risk. (October 2019)

• Record Type: Journal Article
• Authors: Tilahun, Samson; Kifle, Demeke; Zewde, Tigist W.; Johansen, Jostein A.; Demissie, Taye B.; Hansen, Jørn H.
• Is Part Of: Toxicon. Volume 168(2019)
• Page Start: 83
• Page End: 92
• Publication Date: 2019-10
• Subjects: Cyanobacteria -- Intra-cellular -- Extra-cellular -- Eutrophication -- Microcystis, microcystin nitrogen -- Tropical; Toxins -- Periodicals; Venom -- Periodicals; 615.9
• DOI: 10.1016/j.toxicon.2019.06.217
• Languages: English
• ISSNs: 0041-0101

Abstract

Abstract: This study was carried out with a view of understanding the temporal dynamics of microcystin concentrations in both algal seston and water samples and the associated public health risk. All the major MC variants, namely MC-LR, MC-YR, and MC-RR, were detected in both the algal seston and water samples. In the majority of the samples, the most potent variant, MC-LR, constituted the greatest proportion of the total MC concentration suggesting extremely high potential public health risk. The exceptionally high concentrations (μg L −1 ) of all the variants, MC-LR (815), MC-YR (466.6) and MC-RR (265.68), were observed in May. Although the extracellular MCs were relatively less concentrated and less frequently detected, concentrations (μg L −1 ) of up to 20 of MC-LR, 6.13 of MC-YR, and 1.27 MC-RR were encountered. The strong and significant association between Microcystis abundance and concentration of nitrate (Spearman Rank Order Correlation r = 0.793, p < 0.001) may suggest that nitrate is the key dictating factor in the dynamics of Microcystis, and may have consequently influenced the MC levels in the reservoir. Highlights: This study is the first report on microcystin levels in Koka reservoir involving both algal seston and water samples. This study revealed extremely high public health risk associated with cyano-toxin in the reservoir. Microcystin (MC) exceeded the permissible level in the majority of samples despite low Microcystis abundance. MC-LR, the most potent toxin constituted the greatest proportion compared to other variants in majority of the samples.