Population-level Consequences Of Exposure Of Fish To Oestrogenic Wastewater Treatment Works Effluents

英国许多河流中有相当多的水来自污水处理厂（WWTW）的废水，这可能会影响当地的野生动物。我们已经证明，生活在英国许多河流中的鱼类，尤其是蟑螂（鲤鱼家族的一种常见成员）的生殖能力，由于接触了污水中含有的化学物质而受到损害，这些化学物质会破坏人体的性激素系统。产生这些影响的化学物质是雌激素（女性性激素），包括天然雌激素、女性服用的避孕药中的药物雌激素，以及一些结构与天然雌激素相似的工业化学品。雌性化鱼类在野外的存在令人担忧，因为我们已经证明它们的繁殖能力下降，这可能会对种群产生不利影响，并更广泛地影响生态系统。人类生殖健康出现的紊乱在性质上与在野生鱼类中看到的影响非常相似，其中一些影响与接触雌激素有关。人们对英国河流中污水排放的进一步担忧是，长期接触鱼类已经发现了额外的不利健康影响，包括破坏免疫系统和基因损伤。该项目旨在调查暴露于雌性WWTW废水对生活在英国河流中的鱼类种群可持续性的可能后果，使用蟑螂作为哨兵物种。虽然蟑螂在许多受污染的水系统中很常见，但这有时会给人以人口健康状况的误导印象。有争议的是，计算种群中繁殖个体的数量比计算鱼的总数更好，因为繁殖鱼类数量少的种群遗传变异和近亲繁殖较少，甚至可能面临灭绝的危险。根据我们迄今为止进行的实验结果，我们认为来自污染更严重地区的蟑螂种群的繁殖个体数量会更少，而且会比来自干净地区的蟑螂种群的近亲繁殖更多，因为更高比例的鱼将无法繁殖。为了调查这一点，我们将首先评估蟑螂在群体中繁殖的能力，这些群体包括一生都暴露在具有雌性激素的污水处理厂废水中的鱼和一生都生活在清洁水中的鱼。我们将使用一种遗传技术（DNA微卫星）来识别所产生后代的父母，进而确定竞争群体中个体鱼的繁殖成功率，并试图将这种成功与它们的性生理联系起来。然后，我们将进行实验，研究暴露在雌性污水处理厂污水中超过一代和两代如何影响第二代的睾丸和卵巢发育以及随后的繁殖成功。在这个项目的最后一部分，我们将使用DNA微卫星来调查英国河流中野生蟑螂种群的潜在遗传健康，这些种群来自不同程度的污水处理厂雌激素污染的河流。最终，我们的研究结果将使我们能够评估长期暴露于雌性WWTW废水对个体和种群的影响，从而显著提高对英国河流中蟑螂种群可持续性如何受到影响的认识。这项工作的目的是大大改进对接触复杂化学排放物混合物对自然环境中鱼类种群健康影响的评估，以便更好地保护我们的水生资源和生物多样性。这项工作将对排放的监管具有重要意义，因此对政府监管机构、环境保护团体、工业和广大公众都非常感兴趣。

A very significant amount of the water flowing in many UK rivers originates from the effluent of wastewater treatment works (WWTW) and this can affect the native wildlife. We have shown that reproduction in fish living in many UK Rivers, most notably in the roach, a common member of the carp family of fish, has been damaged by exposure to chemicals contained in the WWTW effluents that disrupt the body's sex hormone systems. The chemicals identified responsible for these effects were oestrogens (female sex hormone) and included natural oestrogen hormones, pharmaceutical oestrogens taken by women as part of the contraceptive pill, and some industrial chemicals similar in their structure to natural oestrogens. The presence of feminised fish in the wild is of concern because we have shown that they have a reduced capacity to breed and this may potentially lead to adverse effects for the population and impact the ecosystem more widely. Disorders in human reproductive health occur that are very similar in nature to effects seen in wild fish and some of these effects have been associated with exposure to oestrogens. Adding further concern about WWTW effluents in UK Rivers, long term exposures of fish have found additional adverse health effects including disruption to the immune system and genetic damage. This project seeks to investigate the likely consequences of exposure to oestrogenic WWTW effluents for the sustainability of fish populations living in UK Rivers, using the roach as sentinel species. Although the roach is very common in many polluted water systems, this can sometimes give misleading impressions of the health of the population. Arguably, it is better to count the number of breeding individuals in a population rather than the total number of fish because fish populations with low numbers of breeding fish have low genetic variation and inbreeding and may even be at risk of extinction. Given the results of our experiments performed to date, we think that populations of roach from more polluted sites will have smaller numbers of breeding individuals and will be more inbred than those from clean sites, because a higher proportion of fish will be unable to breed. To investigate this we will first make assessments on the ability of roach to breed in in groups that include fish that have been exposed throughout their whole lives to an oestrogenic WWTW effluent and fish that have been maintained throughout their lives in clean water. We will use a genetic technique (DNA microsatellites) to identify the parents of the offspring produced and in turn determine the reproductive success of individual fish in the competing groups and try to relate this success to their sexual physiology. We will then conduct experiments to investigate how exposure to the oestrogenic WWTW effluent over one and two generations impacts the development of the testes and ovaries and consequent breeding success in the second generation. In the final part of this project we will investigate the underlying genetic health of wild roach populations in UK Rivers using DNA microsatellites for populations collected from rivers sites with different levels of pollution with oestrogenic WWTW effluent. Ultimately, our results will enable us to assess the implications of life long exposure to oestrogenic WWTW effluents on both individuals and populations, advancing significantly knowledge on how the sustainability of roach populations in UK Rivers may be impacted. This work is intended to greatly improve the assessment of the health impacts of exposure to complex mixtures of chemical discharges on fish populations in the natural environment for the better protection of our aquatic resources and biodiversity. The work will have importance in the regulation of discharges and thus is of very wide interest to the government regulatory bodies, environment protection groups, industry and the wider public.