Four Environmental Hormones On Calyciflorus Rotifer Life History And Reproductive Effects

Rotifers are useful as models in ecotoxicology because they play an important in the freshawater and marine ecosystems. Using the rotifer to evaluate environmental hormone effect is a worldwide concern. The effects of bisphenol A (BPA), atrazine, carbaryl and monocrotophos on the acute test, life history, asexual and sexual reproduction of Brachionus.calyciflorus were studied. The main results were presented as the following:1. The effect of BPA on the acute toxicity (24hLC50) of BPA for B. calyciflorus was13.76mg/L. BPA had a significant interference effect on the life stage and life table parameter, especially on the effect of sexual reproduction. In the life history test, the tested concentration0.25-4.0mg/L had no significant effect on the embryonic development compared to the control, BPA at2.0and4.0mg/L extended significantly the durations of juvenile development than the control, but shortened the reproductive period and post-reproductive period. BPA at0.5mg/L increased significantly net reproduction rate (Ro) compared the control. But BPA at2.0and4.0mg/L decreased significantly the Ro, and BPA at4.0mg/L reduced the generation time (7). BPA from1.0to4.0mg/L decreased significantly the intrinsic rate of increase (rm), the mix rate of total offsprings was increased markedly at0.5and1.0mg/L than the control. The results showed that different endpoints of both development and reproduction had different sensitivity to BPA. Ro and mixis rate endpoint of the rotifers appeared to be more sensitive than other endpoints. The effects of BPA (0.313,0.0625,0.125,0.25,0.5,1.0mg/L) on the population growth rate (r) of rotifer at2d showed that BPA at0.5,1.0mg/L reduced markedly the r, other concentration did not affect the r. The reproduction of3d indicated that BPA from0.25mg/L to1.0mg/L decreased significantly the mictic female/amictic female (MF/AF), mix rate (MR) than the control. At the same time, BPA from0.125mg/L reduced the fertilization rate (FR). The resting egg (RE) production at7d showed that the BPA from0.125mg/L reduced the RE production, and0.0625mg/L and above decreased significantly the resting egg hatching rate at3d. All these results indicated that resting egg hatching rate were most sensitive parameter and resting egg production, fertilization rate were second to assess environmental hormone effect of BPA.2.24h median lethal concentration (24h LC50) value of atrazine for B. calyciflorus were39.2mg/L. life history (rotifer exposed atrazine0.04-10.24mg/L) showed that atrazine from0.64to10.24mg/L significantly pronged pre-reproductive period (JP) compared to the control, atrazine from2.56to10.24mg/L extended significantly the embryonic development time, but reduced significantly the reproduction period and mean life span. Atrazine did not affect the post reproduction period of rotifer. Life table showed that atrazine from0.64mg/L to10.24mg/L decreased significantly the rm,2.56-10.24mg/L reduced markedly the eo and R0, the concentration from0.04mg/L to10.24mg/L had no effect on the Tthan the control. The recovery of rotifer exposed atrazine concentration showed that the first rotifer(1st) produced from mother rotifer(Fo) raised at free atrazine, first brood F1(1st) produced by Fo exposed from2.56and10.24mg/L had no significant effect on pre-reproductive period(PP), reproduction period (RP), mean life (ML), e0and Ro, but from the second brood F1(2nd) from the Fo exposed atrazine all the parameter had been recovered except rm of rotifer produced from the F0exposed2.56-10.24mg/L, PP, Ro of F1(2nd) produced from the mother female (Fo) exposed10.24mg/L had not been recovered, all these results showed that atrazine had potential effect on the offsprings.3. Acute toxicity of carbaryl on the rotifer24h LC50was4.10mg/L. Carbaryl from1.6to2.0mg/L extended the pre-reproductive period (JP), but reduced the PP and ML, concentration from1.2mg/L to2mg/L extended significantly embryonic development time (EP),2.0mg/L decreased markedly PP. Life table showed carbaryl from0.8to2.0mg/L decreased significantly Ro and rm, concentration from1.2mg/L reduced significantly T and e0.Effect of rotifer populations were exposed to atrazine at low concentrations from0to5.12mg/L and carbaryl from0.02mg/L to1.62mg/L, the2-d population growth rate,3-d reproduction parameter,7-d resting egg production (RE), and3-d resting egg hatching rate (HR) were measured. The results showed that atrazine concentration had effect on the mix rate, male number and fertilization rate, and no effect on OF/NOF. The no effect concentration (NOEC) and lowest effect concentration (LOEC) of atrazine were1.28mg/L and5.12mg/L for population growth rate (r), and for carbaryl were0.54mg/L and1.62mg/L. In sexual reproduction, the NOEC and LOEC of atrazine for MR were0.32and1.28mg/L. However, carbaryl did not show similar results because0.06mg/L carbaryl increased the MR compared with the control. The NOEC and LOEC of atrazine for RE and HR were the same (0.08and0.32mg/L) and the NOEC and LOEC of carbaryl for RE were slightly lower. HR was the most sensitive of all indices with NOEC and LOEC of atrazine from0.02to0.32mg/L nominal concentration. The result showed that the resting egg hatching rate was the most sensitive parameter to atrazine and carbaryl.4. Effect of monocrotophos on the life history and reproduction of rotifer were investigated. The24h median lethal concentration value was5.65mg/L. Life history indicated monocrotophos from0.25to2.0mg/L prolonged significantly pre-reproduction period, total eggs, Ro and rm,1.0-2.0mg/L reduced markedly the RP, PP and ML. The results of3d population growth test showed that monocrotophos at0.5mg/L reduced the r,0.25mg/L decreased significantly the mix rate, but had no effect on the fertilization rate, concentration from0.125to0.5mg/L decreased significantly the resting egg production,0.0625-0.5mg/L decreased markedly the resting egg hataching rate. The results showed that resting egg hating rate was the most parameter, and discovered that the fertilization rate sometimes was not the more sensitive parameter than other reproductive parameters.5. Atrazine (0,0.02,0.08mg/L) and monocrotophos(Mop)(0、0.0079、0.0157、0.0313mg/L) had no significant effect on r at2d, MR, OF/NOF, FR at4d, resting egg production at7d of rotifer respectively. But atrazine mixed Mop at different concentrations, the reproductive parameters of rotifer had been affected depended on the concentrations of atrazine and Mop concentration. Atrazine at0.08mg/L mixed Mop at0.0313mg/L had significnt effect on reproduction of rotifer. But atrazine at lowerst concnentration mixed Mop at lowerest concentration had no significant effect on the reproduction of rotifer compared the control. Other concentrations mixed affected the reproduction of rotifer between the lowest and highest concentrations. Compound effect of atrazine and mop on the resting egg production in all reproductive indicides is the most sensitive. The results showed that simple environment hormone could not assess the envirnonmental effect on rotifer fully, but when different environmental hormone mixed, they could affect the reproduction of rotifer. The results showed that the simple environmental hormone might not affect the reproduction of rotifer, but different environmental hormone combined, the reproduction of rotifer might be affected.