University of Exeter, Biosciences, College of Life & Environmental Sciences, Exeter EX4 4PS, United Kingdom.
Environ Sci Technol. 2011 Feb 15;45(4):1673-9. doi: 10.1021/es103232q. Epub 2011 Jan 5.
Feminized responses are widespread in wild populations of roach, Rutilus rutilus, living in UK rivers, and some of these responses have been shown to arise as a consequence of exposure to wastewater treatment works (WwTW) effluent discharges and the endocrine disrupting chemicals (EDCs) they contain. The causation of the ovotestis condition in wild roach, however, has yet to be established. Furthermore, the impact of long-term exposure to WwTW effluents on the reproductive fitness of wild fish populations is not known, and this information is crucial for population level effect assessments. We undertook a chronic exposure of roach to a treated estrogenic wastewater effluent for up to 3.5 years to assess principally for effects on subsequent reproductive fitness, as determined through parentage analysis on offspring from a competitive breeding study. In generating the fish for the breeding study we found that exposure to full strength WwTW effluent until sexual maturity resulted in sex reversal in almost all males in the population; 98% of the exposed fish were phenotypic females, containing ovaries. Furthermore, fish exposed to a 50% dilution of WwTW effluent contained ovotestis (21% of the male roach) that was absent from the control population. In competitive breeding studies, and applying DNA microsatellites to assess parentage, we show that presumptive females exposed to sexual maturity to WwTW effluent bred normally, albeit in the absence of nonexposed females, but putative sex-reversed males breeding as females contributed poorly, if at all, in a breeding population, depending on the competition. These novel findings on sex reversal add a new dimension for impact assessments of exposure to WwTW effluents on fish populations.
在英国河流中生活的罗非鱼野生种群中，雌性化反应非常普遍，其中一些反应是由于暴露于污水处理厂（WwTW）的污水排放及其所含的内分泌干扰化学物质（EDCs）所致。然而，野生罗非鱼卵睾的成因尚未确定。此外，长期暴露于 WwTW 污水对野生鱼类种群生殖适应性的影响尚不清楚，而这些信息对于种群水平的效应评估至关重要。我们对罗非鱼进行了长达 3.5 年的慢性雌激素处理废水暴露实验，主要评估了对后代生殖适应性的影响，这是通过竞争繁殖研究中的亲子关系分析来确定的。在进行繁殖研究的鱼类生成过程中，我们发现，暴露于全强度 WwTW 污水直到性成熟会导致种群中几乎所有雄性的性别反转；暴露组的 98%的鱼都是表型雌性，含有卵巢。此外，暴露于 WwTW 污水 50%稀释液的鱼类存在卵睾（雄性罗非鱼的 21%），而对照组中则没有。在竞争繁殖研究中，我们应用 DNA 微卫星来评估亲子关系，结果表明，暴露于 WwTW 污水至性成熟的假定雌性可以正常繁殖，尽管在没有未暴露雌性的情况下，但作为雌性繁殖的假定性反转雄性贡献很差，如果有的话，这取决于竞争。这些关于性别反转的新发现为评估暴露于 WwTW 污水对鱼类种群的影响增加了一个新的维度。
