Occurrence of microcystins in freshwater bodies in Southern Mozambique.

Sammendrag

Many countries have started to monitor cyanobacterial cell densities and microcystin concentrations in raw water sources and recreational water due to human and animal poisonings and the results of toxicological studies, which have shown the adverse effects of microcystins to some mammals. Mozambique has no reports of intoxications or deaths of animals or human by cyanobacterial toxins. However, blooms of cyanobacteria have been reported in some aquatic ecosystems. The aim of this study was to detect and quantify the microcystins extracted in water samples from Pequenos Libombos Dam, Nhambavale Lake and Chòkwé Irrigation Channel, all located in southern Mozambique using LCMS. The Microcystins MC-LR, -YR and –RR were detected in the three sampling areas. MC-LR was found in higher concentrations than the other two variants. The highest total concentration of microcystins detected was 7.89 μg/L in water samples from Nhambavale Lake. Pequenos Libombos Dam revealed concentrations of MC-LR at below quantifiable levels. Based on these results, it is recommended that drinking water supplies in Mozambique are monitored and that the risks of human and animal intoxication by cyanotoxins are assessed and managed.