Responses in the population growth and reproduction of freshwater rotifer Brachionus calyciflorus to four organochlorine pesticides

摘要

In China, although the production and use of organochlorine pesticides (OCPs) have been banned for decades, relatively high levels of OCP residues have still been found in some water bodies, and can result in adverse acute and chronic effects on zooplankton including rotifers, which have caused public concern for many years. Responses in the population growth and reproduction of freshwater rotifer Brachionus calyciflorus to four OCPs including aldrin, dieldrin, b-hexachlorocyclohexane (b-HCH) and chlordecone were studied by 3-day population growth and 4-day resting eggs (RE) production tests. In comparison with control, aldrin at 10 mg.Lx1, b-HCH at 1000 mg.Lx1 and chlordecone at 0.05 mg.Lx1 significantly increased the population growth rate (r); but aldrin at 100 mg.Lx1, dieldrin at 0.001 and 0.1 mg.Lx1, b-HCH at 0.1-100 mg.Lx1 and chlordecone at 50 mg.Lx1 markedly decreased it. Aldrin at concentrations higher than 1 mg.Lx1, dieldrin at 0.01 and 1000 mg.Lx1, b-HCH at concentrations 0.1 and higher than 1 mg.Lx1, and chlordecone at concentrations 0.005 and higher than 0.5 mg.Lx1 significantly decreased the ratio of ovigerous females to non-ovigerous females (OF/NOF), but the reverse was true for aldrin at 0.1 mg.Lx1 and b-HCH at 0.001 mg.Lx1. Dieldrin at 0.001, 0.01 and 1000 mg.Lx1 significantly decreased the ratio of mictic females to amictic females (MF/AF), but b-HCH at 1 and 10 mg.Lx1 highly significantly increased it. Dieldrin at 1000 mg.Lx1 and b-HCH at concentrations higher than 10 mg.Lx1 markedly decreased the fertilization rate (FR). Both aldrin and chlordecone have no significant effect on the MF/AF and FR of rotifers. Aldrin at concentrations higher than 1 mg.Lx1, dieldrin at lower than 0.1 and higher than 10 mg.Lx1, b-HCH at 1000 mg.Lx1 and chlordecone at 0.005, 0.05 and 50.0 mg.Lx1 significantly decreased the mictic rate (MR) of rotifers, but the reverse was true for b-HCH at 1 mg.Lx1. Aldrin at 10 mg.Lx1, dieldrin at 0.001, 0.1 and 1000 mg.Lx1, b-HCH at concentrations higher than 1 mg.Lx1 and chlordecone at concentrations higher than 0.005 mg.Lx1 markedly decreased RE production of rotifers, but b-HCH at 0.01 mg.Lx1 significantly increased it. A clear dose-response relationship existed between the RE and the concentration of dieldrin, b-HCH and chlordecone, and the OF/NOF and the aldrin concentration. The RE and OF/NOF in rotifer population might be suitable endpoints for monitoring the low concentration of three OCPs (dieldrin, b-HCH and chlordecone) and aldrin, respectively.