Effects of bisphenol A on the toxicity and life history of the rotiferBrachionus calyciflorus

应用生态毒理学研究方法,研究了双酚A(BPA)对萼花臂尾轮虫毒性及生活史影响。结果表明:BPA对萼花臂尾轮虫24 h急性毒性LC₅₀为13.76 mg/L,95%置信限为10.97-17.10 mg/L。生活史研究显示:与对照组相比,0.25-4.0 mg/L的BPA对轮虫胚胎发育历时影响不显著;2.0-4.0 mg/L的BPA显著延迟了轮虫幼体发育时间;当BPA为0.5 mg/L时,轮虫净生殖率(R₀)显著上升,但BPA浓度为2.0和4.0 mg/L时R₀显著降低;4.0 mg/L的BPA显著缩短世代时间(T);BPA浓度为2.0、4.0 mg/L时,轮虫生命期望值(e₀)显著下降;BPA浓度为1.0、2.0、4.0 mg/L时,轮虫内禀增长率(r_m)显著下降;BPA浓度为0.5、1.0 mg/L时轮虫所产后代混交率(MR)显著增长。研究结果表明BPA对轮虫的生殖具有干扰作用,其中R₀和MR受BPA影响最为显著。;The presence of toxic agents in aquatic environments has increased in recent years. Some of them that are released into the aquatic environment interfere with the endocrine system of organisms by affecting development time, causing reproductive abnormalities and reducing population growth rates in zooplankton including rotifers. Bisphenol A (BPA, 4,4¹-isopropylidine diphenol) is a commercially important chemical with an estimated worldwide production capacity of 3.7 million metric tons per year and demonstrates estrogenic activity. Many acute and chronic toxicity studies under controlled conditions have used either fish or the cladoceran Daphnia magna. However there is little information using rotifers with BPA. With short life spans and high reproductive abilities, rotifers such as Brachionus calyciflorus are particularly useful for environmental toxicology because of their higher sensitivities to most toxicants. Moreover, rotifers are important trophic components of aquatic food webs constituting a major food source for fish and invertebrate predators and thus play a vital role in transporting energy and nutrients in aquatic ecosystems. The aim of the present work was therefore to use B. calyciflorus to study the effect BPA on the life history characteristics and mixis.
Population of B.calyciflorus was (0-2 h old) obtained by hatching resting eggs in EPA medium. Resting eggs were endowed by professor T W. Snell. Test toxicant solutions were prepared by US EPA medium. The rotifers were fed using unicellular green algae Chlorella pyrenoidosa at 1.0×10⁶ cells/mL,the alga was cultured in a semi-continuous culture using HB-4 medium in 3 L transparent flasks under a light intensity of 4000 lux and photo period was 12∶12 (L∶D). The results showed that 24 h median lethal concentration (24 h LC₅₀) value of BPA for B. calyciflorus was 13.76 mg/L, and 95% limits was 10.97-17.10 mg/L. In the tested concentration range of 0.25-4.0 mg/L, BPA at 2.0 and 4.0 mg/L extended significantly the durations of juvenile development and total eggs production. At 2.0-4.0 mg/L BPA did not affect significantly the durations of embryonic development. BPA concentration at 0.5 mg/L increased markedly net reproductive rate (R₀), 2.0-4.0 mg/L decreased R₀. BPA concentration had no effect on generation time (T) except at 4.0 mg/L. BPA concentration from 1.0 to 4.0 mg/L decreased the intrinsic rate of population increase (r_m), 0.5, 1.0 mg/L increased significantly mixis rate of B.calyciflorus. The results showed that different endpoints of both development and reproduction had different sensitivity to BPA. R₀ and mixis rate endpoint of the rotifers appeared to be more sensitive than other endpoints.