Biological Journal of Microorganism (Mar 2017)
Effects of different types of herbicides and insecticides on population of green microalgae Scenedesmus quadricauda
Abstract
Introduction:Agricultural pesticides into aquatic ecosystems of use discriminate eventually devastating impact on the populations of aquatic species.Sensitivity of algae to various pollutants such as herbicides, organochlorin, heavy metals and industrial organic matter has been shown in various studies. In addition to its application, checking the pollution is common. This study aimed to investigate the effects of different concentrations of two groups of herbicides, (macheteand saturn), and insecticides (malathion and diazinon) on the population of green algae (Scenedesmusquadricauda) with 96 hour EC50. Materials and methods: The experiment was conducted in a completely randomized design during 96 hours in 4 treatments (four levels of pesticide and control) and 3 replicates in accordance with the standard method, OECD. The exposure regime consisted of a 12-hour photoperiod with a 12:12light-dark regimewith intensity of 80 µmol photons/m2/s in BBM medium (Bold Basal Medium) at 22± 2 °C. Results: Statistical analysis of results also showed significant differences in daily growth rate (p < 0.05) between some different concentrations of studied toxic material, as the significant changes in the cell density observed by increasing concentrations of toxins. The highest mortality rate caused by herbicides in 52.81 µg/L of saturn and 58.36 µg/L ofmachete, and by insecticides in 63.76 µg/L of malathion and 6.087 µg/L. Also, 96 hour EC50was determined, as 174.234 µg/L for diazinon, 9.858 µg/L formalathion,1.9µg/L formachete and 1.029µg/Lfor Saturn. Discussion and conclusion: According to the results of this study, (Scenedesmus quadricauda) can be used as a biological indicator in aquatic ecosystems while it needs more extensive and intensive studies.
