Section 16
Chapter 15,625

Effect of pulsed exposure to heavy metals (copper and cadmium) on some population variables of Brachionus calyciflorus Pallas (Rotifera : Brachionidae : Monogononta)

Gama-Flores, J.-Luis; Castellanos-Paez, M.-Elena; Sarma, S.S.S.; Nandini, S.

Hydrobiologia 593: 201-208


ISSN/ISBN: 0018-8158
DOI: 10.1007/s10750-007-9042-0
Accession: 015624039

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Heavy metals are widely recognized as potential toxic agents to zooplankton, yet experiments are usually performed with a continuous exposure to the metal being analyzed. Here we describe experiments that examined the influence of pulsed exposure of the heavy metals copper and cadmium to a parthenogenetic population of the planktonic rotifer Brachionus calyciflorus. Our protocol called for exposure durations of 3, 6, 12, and 24 h to either copper ( as CuSO4) at concentrations of 0.0375, 0.075, 0.15 mg l(-1) or cadmium ( as CdCl2) at concentration of 0.025, 0.05, 0.1 mg l(-1). Control animals were treated in similar ways but did not receive exposure to heavy metals. Four end points were used to evaluate the outcome of exposure: population growth ( r), body size, egg ratio, and egg hatching percent. Increase in heavy metal concentration and exposure time had an adverse influence on the population growth of B. calyciflorus. However, while the response of B. calyciflorus was similar for both heavy metals, the magnitude of the impact of cadmium was more severe. Population growth varied depending on which heavy metal was tested, as well as its concentration and the duration of exposure ( r = 0.11 - 0.28 day(-1)). There was a significant reduction in lorica size of B. calyciflorus subjected to different exposure times and concentrations of both Cd and Cu. Egg ratios were inversely related to population density in controls and in treatments involving Cu, but not for Cd. While nearly 100% of eggs hatched in the control treatments, egg hatching in experimental treatments containing Cu, were reduced ( range = 16 - 41%) depending on the exposure time and the concentration.

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