The toxic effect of three allelochemicals on natural algal assemblage and Moina macrocopa.

To safely and effectively apply fatty acids and phenolic acids to control and prevent water-bloom,the article studied the toxicity of linoleic acid,salicylic acid and p-hydroxybenzoic acid on natural algal assemblage of pond water and zooplankton Moina macrocopa.The results showed that linoleic acid had the strongest toxicity,while salicylic acid and p-hydroxybenzoic acid had moderate toxicity on the natural algal assemblage of pond water,when the concentration of linoleic acid was 0.3mg/L,the biggest inhibitory ratio was up to 87.6%.The collective activity of a mixture of two allelochemicals were also examined and the synergistic growth inhibition on the natural algal assemblage were proved,in which the mixture of linoleic acid and salicylic acid had stronger toxicity.The three allelochemicals to some extent also showed toxicity on Moina macrocopa,but linoleic acid had stronger toxicity,while salicylic acid and p-hydroxybenzoic acid had lower toxicity on Moina macrocopa,the EC50s of the three allelochemicals on Moina macrocopa was far higher than the EC50s on the natural algal assemblage,which indicated that there exists great potential for using the three allelochemicals,especially linoleic acid,to be developed biological algicide agent while no evident toxicity on environment within the concentrations of controling the growth of water-bloom algae.