Multigenerational cadmium acclimation and biokinetics in Daphnia magna.
A Cd exposure (3 microg L(-1)) experiment was conducted for six successive generations to investigate the responses to chronic Cd stress in Daphnia magna. We observed a biphasic accumulation of Cd in the six generations and suggested a similar pattern with respect to daphnids' tolerance. Cd assimilation efficiencies, daphnid growth, and reproduction corresponded to the changes of tolerance, which was partially accounted for by metallothionein induction. When maternally exposed neonates grew in Cd-free water for one or two generations, their growth, MT concentration and biokinetic parameters partially or totally recovered. The rapid recovery suggests the high potential for ecological restoration from Cd pollution. Our results indicate that the tolerance of sensitive D. magna clones to Cd was dependent on long-term or multigenerational exposure. The tolerance developed within the first several generations might not be maintained, and the animals may become even more sensitive to Cd stress in subsequent generations.
Guan
Rui
R
Atmospheric Marine Coastal Environment Program, and Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
Wang
Wen-Xiong
WX
D000064:Acclimatization; D000222:Adaptation, Physiological; D000818:Animals; D001682:Biological Availability; D002104:Cadmium / Q000032:analysis* / Q000493:pharmacokinetics / Q000633:toxicity; D003621:Daphnia / Q000737:chemistry* / Q000254:growth & development / Q000502:physiology; D004435:Eating / Q000502:physiology; D004781:Environmental Exposure / Q000009:adverse effects; D008668:Metallothionein / Q000032:analysis; D012098:Reproduction / Q000502:physiology; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000493:pharmacokinetics / Q000633:toxicity
D014874:Water Pollutants, Chemical; D002104:Cadmium; D008668:Metallothionein