Effects of dieldrin and 17β-estradiol on life history characteristics of freshwater rotifer Brachionus calyciflorus Pallas

Abstract

The effects of dieldrin and 17β-estradiol (E2) at seven concentrations (0.001, 0.01, 0.1, 1, 10, 100 and 1000 µg/L) on development, survival and reproduction of the freshwater rotifer B. calyciflorus were studied using a life table demographic method. Compared to the control, dieldrin at 0.01, 0.1 and 10 µg/L and E2 at 0.001–0.1 and 10 µg/L shortened the duration of embryonic development (p < 0.05). E2 at 0.01, 0.1 and 10 µg/L prolonged the juvenile period but dieldrin at 1000 µg/L shortened the juvenile period of the rotifers (p < 0.01). Dieldrin at 0.001–100 µg/L, and E2 at 0.001, 0.01, 1, 100 and 1000 µg/L prolonged the reproductive period of the rotifers (p < 0.01), Dieldrin at 0.001 and 10–1000 µg/L and E2 at 100 and 1000 µg/L prolonged the post-reproductive period of the rotifers (p < 0.05). Dieldrin at 100 µg/L decreased the intrinsic rate of population increase of rotifers but the reverse was true for E2 at 1 µg/L. The net reproduction rate was increased by dieldrin at 0.001 µg/L and E2 at 100 and 1000 µg/L. Dieldrin at 0.001–1000 µg/L and E2 at 0.01, 100 and 1000 µg/L prolonged the generation time. Life expectancy at hatching was prolonged by dieldrin at 0.001–1000 µg/L and E2 at 0.01, 1, 100 and 1000 µg/L. Both dieldrin and E2 at low concentrations caused a shortening in the duration of embryonic development, an increase in the reproductive period, post-reproductive period, net reproduction rate, generation time, and life expectancy at hatching of B. calyciflorus.