Department of Biology, University of Waterloo, 200 University Ave W., Waterloo, ON, N2L 3G1, Canada.
Aquat Toxicol. 2012 Apr;110-111:149-61. doi: 10.1016/j.aquatox.2012.01.004. Epub 2012 Jan 13.
During the winter low flow periods, Wascana Creek, Saskatchewan, Canada, can be 100% treated municipal wastewater downstream of the City of Regina's Wastewater Treatment Plant. The objective of this study was to determine if exposure to municipal effluent affects the health and reproductive development of fish in an effluent-dominated stream. Field studies were conducted on post-spawning (August 2006), spawning (June 2007), recrudescent (October 2007) and pre-spawning (May 2008) sentinel fish [Fathead Minnow Pimephales promelas and Brook Stickleback Culaea inconstans] to assess responses in terms of growth (condition factor), reproduction (in vitro sex steroid biosynthetic capacity, and gonadosomatic indices, histology) and survival associated with the effluent outfall. Sentinel species demonstrated varying responses depending on the season of field collections. While Stickleback collected downstream of the sewage discharge were often longer, heavier and had greater condition, Fatheads from the same site were shorter and lighter. Exposed fish of both species exhibited delayed spawning and altered gonadal development depending on the season. Exposed male Fathead Minnows also had significantly lower scores of secondary sexual characteristics (fewer nuptial tubercles, little or no development of the dorsal pad, and the lack of presence of a dorsal fin dot). Histopathology of exposed Fathead Minnows revealed thickening of the gill lamellae and alterations in structure of the kidneys (inflammation of the proximal tubules and Bowman's capsule). It is not known if the effluents are affecting natural reproduction and recruitment into this population or if these impacted populations rely on immigration from upstream reaches to sustain the populations. Climate change and human population growth will further challenge this effluent-dominated stream's ability to assimilate nutrients and contaminants which may further impair the performance of fish in this arid environment.
在冬季低流量期间，加拿大萨斯喀彻温省的瓦斯卡纳溪在里贾纳市污水处理厂下游可接纳 100%经处理的城市废水。本研究的目的是确定暴露于市政污水是否会影响以污水为主的溪流中鱼类的健康和生殖发育。实地研究于产卵后（2006 年 8 月）、产卵期（2007 年 6 月）、恢复期（2007 年 10 月）和产卵前期（2008 年 5 月）对[黑头呆鱼（Pimephales promelas）和溪红点鲑（Culaea inconstans）]示踪鱼进行了研究，以评估与污水排放口相关的生长（条件系数）、繁殖（体外性类固醇生物合成能力和性腺指数、组织学）和存活的反应。示踪物种的反应因野外采集季节而异。虽然在污水排放口下游收集的棘鱼通常更长、更重、状况更好，但来自同一地点的黑头呆鱼则更短、更轻。两种鱼类的暴露鱼都表现出随季节而延迟产卵和改变性腺发育。暴露的雄性黑头呆鱼的第二性征（较少的婚垫、背部垫的发育很少或没有、缺乏背部鳍点）评分也明显较低。暴露的黑头呆鱼的组织病理学显示鳃片增厚和肾脏结构改变（近端小管和鲍曼氏囊炎症）。目前尚不清楚污水是否会影响该种群的自然繁殖和补充，或者这些受影响的种群是否依赖上游的移民来维持种群。气候变化和人口增长将进一步挑战这条以污水为主的溪流同化营养物质和污染物的能力，这可能进一步损害这种干旱环境中鱼类的表现。
