Environment Agency, Red Kite House, Howbery Park, Wallingford, Oxon, UK.
Aquat Toxicol. 2011 Jan 25;101(2):326-34. doi: 10.1016/j.aquatox.2010.11.005. Epub 2010 Nov 19.
Whilst the effects of oestrogenic contaminants in the aquatic environment are well documented in fish, effects in invertebrate species has been subject to debate, possibly due to differences in experimental conditions (temperature, timing and duration of exposure) between studies. It has been suggested that molluscs are only susceptible to oestrogens in periods either following the main spawning or leading up to the maturation of gametes. To investigate this possibility, two temperate, seasonally reproducing gastropods (Planorbarius corneus and Viviparus viviparus) were exposed to two concentrations of 17β-oestradiol (E2; 10ng/l and 100ng/l nominal) in an outdoor mesocosm (subject to natural seasons). In addition, P. corneus was also exposed to E2 (1, 10 and 100ng/l) in the laboratory at temperatures and photoperiods to simulate summer and autumn. In the mesocosm, both snail species produced similar numbers of eggs/embryos as reference groups in the summer, but the groups exposed to 10ngE2/l (nominal) had significantly higher productivities after the onset of autumn, when entering their quiescent phase, whilst the snails exposed to a higher concentration (100ng/l, nominal) had an increased rate of mortality, and did not experience increased reproduction. In the laboratory, the rate of egg laying in P. corneus was unaffected in simulated summer (20°C, 16h photoperiod), but snails exposed to 10 and 100ng/l (nominal) in simulated autumn (15°C, 12h photoperiod) showed a concentration-dependent inhibition of the natural decline in egg laying observed in the control snails. Overall, rather than an increase in reproductive rate, the response of this species was a perpetuation of summer reproductive rates into autumn. We conclude that exposure to E2 can affect reproduction in the freshwater gastropods studied, but in P. corneus at least, this is dependent on the seasonal conditions (temperature and photoperiod) at which exposures are made.
虽然水生环境中雌激素污染物对鱼类的影响已得到充分记录，但在无脊椎动物物种中的影响一直存在争议，这可能是由于研究之间实验条件（温度、暴露时间和持续时间）的差异所致。有人认为，软体动物只有在主要产卵期后或配子成熟前的一段时间内才容易受到雌激素的影响。为了研究这种可能性，两种温带、季节性繁殖的腹足纲动物（扁卷螺和圆田螺）在户外中观（受自然季节影响）中暴露于两种浓度的 17β-雌二醇（E2；10ng/l 和 100ng/l 名义浓度）下。此外，扁卷螺还在实验室中以模拟夏季和秋季的温度和光照周期暴露于 E2（1、10 和 100ng/l）。在中观中，两种蜗牛物种在夏季的参考组中产生了相似数量的卵/胚胎，但在秋季开始进入休眠期后，暴露于 10ngE2/l（名义浓度）的组的生产力显著提高，而暴露于较高浓度（100ng/l，名义浓度）的组死亡率增加，并且没有增加繁殖。在实验室中，扁卷螺在模拟夏季（20°C，16h 光照周期）中的产卵率不受影响，但在模拟秋季（15°C，12h 光照周期）中暴露于 10 和 100ng/l（名义浓度）的蜗牛显示出对自然下降的浓度依赖性抑制在对照蜗牛中观察到的产卵。总体而言，这种物种的反应不是繁殖率的增加，而是夏季繁殖率的持续到秋季。我们得出结论，暴露于 E2 会影响研究中淡水腹足纲动物的繁殖，但至少在扁卷螺中，这取决于暴露时的季节性条件（温度和光照周期）。
