Toxicity of Seven Herbicides to the Three Cyanobacteria Anabaena flos-aquae, Microcystis flos-aquae and Mirocystis aeruginosa

The toxicity of 7 herbicides to the three cyanobacteria was tested in this work. The results indicated that: (1) There was a highly significant relationship between dried weight or chlorophyll-a and OD680nm for tested cyanobacteria; (2) the toxicity of the tested herbicides with the order from high to low was: photosynthesis-inhibiting > ACCase inhibitor > protox inhibiting herbicides; (3) the sensitivity of various species exposed to cyanazine, diclofop, prometryn, simazine and simetryn varied by over one order of magnitude. The decreasing order of sensitivity of cyanobacteria to the selected herbicides was: M. Flosaquae > M. Aeruginosa > A. flos-aquae. Cyanobacteria can produce toxins including hepatotoxins e.g. microcystins and endotoxins e.g. lipopolysaccharides. Therefore, the research on comparing the differential sensitivity of cyanobacteria and green algae is of important scientific significance and realistic value