The influence of microcystin-LR and hepatotoxic cyanobacterial extract on the water plant Spirodela oligorrhiza.

The eutrophication of the Sulejów Reservoir dam in Poland is related to toxicity from cyanobacterial blooms. The main species responsible for hepatotoxic bloom formation is Microcystis aeruginosa. The aim of this study was to evaluate the influence of toxic cyanobacterial extract on the growth and morphology of the water plant Spirodela oligorrhiza, compared with commercial-grade microcystin-LR (MC-LR). It was found that after 96 h of incubation the highest concentration of cyanobacterial extract, containing 0.344 mg MC-LR/L, reduced the number of fronds by about 50% in comparison with the control. The extract effected a reduction in the frond mass and a decrease in chlorophyll (a + b) concentration. A reduction in the number of fronds was also observed after the first 24 h of incubation in the presence of 0.2 and 0.1 microg/L of commercial-grade MC-LR. Changes in activity of constitutive acid phosphatase and RNase after 7 days of incubation with commercial-grade MC-LR were observed. The results confirm the toxicity of cyanobacterial hepatotoxins to Spirodela oligorrhiza, which can be used as a sensitive bioindicator.