Department of Biology, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
Aquat Toxicol. 2011 Aug;104(3-4):278-90. doi: 10.1016/j.aquatox.2011.05.008. Epub 2011 May 13.
The Grand River watershed in Ontario, Canada, receives and assimilates the outflow of 29 Municipal Wastewater Effluent (MWWE) discharges which is a mixture of domestic and industrial wastes. The purpose of this study was to investigate the cumulative impact of multiple sewage discharges on populations of wild fish. In field studies, responses of fish populations and individual fish responses in terms of growth (condition factor), reproduction (in vitro sex steroid production, gonadosomatic indices, histology [cellular development and intersex]) were assessed upstream and downstream of two municipal discharges. Fish [Greenside Darters Etheostoma blennioides and Rainbow Darters E. caeruleum] collected downstream of two municipal wastewater plants had the potential to have greater growth (longer and heavier) when compared to reference fish collections regardless of sex. Fish were not assimilating additional anthropogenic resources into energy storage (increased condition, liver somatic index). Impacts on ovarian development appeared to be minor with no differences in growth, steroid production or cellular development. Sewage exposed male fish were experiencing impairment in the capacity to produce testosterone and 11-ketotestosterone in vitro, and in cellular development (GSI, intersex). Male darters of both species collected in the upstream agricultural region demonstrated no evidence of intersex whereas our urban reference sites had incidence of intersex of up to 20%. Rates of intersex were elevated downstream of both sewage discharges studied (33% and>60%, respectively). Lower rates of intersex at the intermediate sites, and then increases downstream of second sewage discharge suggests that fish populations have to potential to recover prior to exposure to the second sewage effluent. Pre-spawning darters demonstrated dramatically higher incidence of intersex in the spring at both urban reference sites (33% and 50%, respectively), and increased more so downstream of the near-field and far-field exposure sites (60% and 100%, respectively). These findings suggest that the compounds released in STP effluents have a tendency to act on the male reproductive system. These effects may become more pronounced as projected human population growth will require the aquatic environment to assimilate an increasing amount of sewage waste.
加拿大安大略省的格兰德河流域接收并同化了 29 个城市污水废水（MWE）排放口的流出物，这些排放物是生活污水和工业污水的混合物。本研究的目的是调查多个污水排放口对野生鱼类种群的累积影响。在野外研究中，评估了两种城市污水排放口上下游鱼类种群和个体鱼类生长（体况系数）、繁殖（体外性类固醇产生、性腺指数、组织学[细胞发育和间性]）的反应。无论性别如何，与参考鱼类采集相比，从两个市政废水厂下游采集的鱼类[格林赛德达特鱼（Etheostoma blennioides）和虹彩达特鱼（E. caeruleum）]生长潜力更大（更长、更重）。鱼类没有将额外的人为资源同化到能量储存中（增加的条件、肝体指数）。对卵巢发育的影响似乎很小，生长、类固醇产生或细胞发育没有差异。暴露于污水的雄性鱼类在体外产生睾酮和 11-酮睾酮以及细胞发育（GSI、间性）的能力受损。在上游农业区采集的两种达特鱼类雄性均未表现出间性的证据，而我们的城市参考点的间性发生率高达 20%。在研究的两个污水排放口下游，间性的发生率升高（分别为 33%和>60%）。在第二个污水排放口下游的中间位点，间性发生率较低，然后升高，表明鱼类种群在暴露于第二个污水废水之前有恢复的潜力。在春季，两个城市参考点的预产卵达特鱼的间性发生率明显更高（分别为 33%和 50%），在近场和远场暴露点下游增加更多（分别为 60%和 100%）。这些发现表明，污水处理厂排放的化合物有倾向于作用于雄性生殖系统。随着预计人口增长，人类将需要水生环境来同化越来越多的污水废物，这些影响可能会变得更加明显。
