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Effects of mercury concentration on life table demography of Moina macrocopa under different Scenedesmus obliquus densities.

HUANG Ya, WANG Ling, MU Wei-ping, REN Tong-tong, PAN Ling, XI Yi-long   

  1. (College of Life Sciences, Anhui Normal University / Collaborative Innovation Center of Recovery and Reconstruction of Degraded Ecosystem in Wanjiang City Belt, Anhui Province, Wuhu 241000, Anhui, China)
  • Online:2015-12-18 Published:2015-12-18

Abstract: In order to compare the chronic toxicity of pollutants to organisms in an aquatic environment under different food densities, the cladoceran Moina macrocopa was used as test animal to investigate the effects of Hg2+ concentrations (0, 0.4, 1.1, 1.8, 2.5, 3.2 and 3.9 μg·L-1) on its life table demography under low (0.5×106 cells·mL-1), medium (1.0×106 cells·mL-1) and high (2.0×106 cells·mL-1) densities of Scenedesmus obliquus. The results showed that at low and high food levels, certain concentrations of Hg2+ had inhibitory effects on survival, reproduction and population growth of M. macrocopa. However, at the medium food level, the inhibitory effects disappeared. Compared with the control, at the low food level, Hg2+ at 0.4-2.5 and 3.9 μg·L-1 significantly decreased the life expectancy at hatching, Hg2+ at 0.4, 1.1, 2.5 and 3.9 μg·L-1 decreased the generation time, Hg2+ at 1.1, 2.5 and 3.9 μg·L-1 decreased the net reproduction rate, and Hg2+ at 3.9 μg·L-1 decreased the gross reproduction rate of M. macrocopa. At the high food level, Hg2+ at 1.1 μg·L-1 decreased the intrinsic rate of population increase, and Hg2+ at 3.9 μg·L-1 decreased the life expectancy at hatching and the net reproduction rate of M. macrocopa. However, at the medium food level, Hg2+ at 3.2 μg·L-1 increased the life expectancy at hatching of M. macrocopa. When S. obliquus density was 0.5×106 cells·mL-1, there were significant doseeffect relationships between Hg2+ concentration and the life expectancy at hatching, the generation time as well as the cross reproduction rate of M. macrocopa. However, when S. obliquus density was 1.0×106 or 2.0×106 cells·mL-1, there were no any significant doseeffect relationships between Hg2+ concentration and each of the life table demographic parameters of M. macrocopa.