Multiple stressors in watersheds

流域暴露于各种污染物，以及自然和人为的压力源，这些压力源可以相互作用，对鱼类和其他生物造成不利影响。污染物通常也以复杂混合物的形式进入流域，具有不同的成分和性质，极大地影响其环境命运、生物利用度和毒性（生态毒理学）。我们目前对这些相互作用缺乏了解，在评估各种人类活动的环境风险时造成了相当大的不确定性，特别是在考虑跨流域的多种压力源时。目前的研究项目正致力于更好地理解污染物对流域的影响和相互作用，以及在自然变化的背景下考虑多种压力源的预测累积效应框架的发展。我们过去的研究表明，城市污水中含有多种化学物质，这些化学物质有可能改变鱼类的生理、代谢和内分泌功能。在格兰德河流域，野生彩虹鲈（Etheostoma caeruleum）暴露于废水排放中，引起了生物组织（从分子到种群）各个层面的变化。不幸的是，由于我们对这些不同的化学物质如何在早期发育过程中相互作用导致鱼类不良后果的理解不足，我们无法将环境中的特定污染物与野生鱼类的影响联系起来。这一建议的重点是将彩虹刺鱼（鱼卵到成鱼）控制在实验室暴露于可能通过不同机制对鱼产生影响的特定化学物质（乙炔雌醇、三氯生、二甲双胍），并与废水（复杂混合物）进行对比。它将测试这些化学物质单独或混合引起（可能增强）生理和生殖方面的各种关键变化的能力，包括基因表达、性腺发育（包括双性人）、性类固醇产生和行为。我们将利用十年来对大河中鱼类的化学暴露和影响数据，以及对最近流出水质变化的反应，开发命运和影响模型，以补充这项研究。最后，我们将开始研究新型功能化纳米颗粒（纳米药物）的环境风险，这些纳米颗粒也有望在不久的将来释放到废水系统中。因此，这项研究将继续促进我们对重要机制和过程的理解，这些机制和过程目前限制了国家和国际机构评估和管理排放到我们流域的这种多样性污染物的不确定性和风险的能力。

Watersheds are exposed to a variety of contaminants, as well as both natural and anthropogenic stressors that can interact to cause adverse effects in fish and other organisms. Contaminants also normally enter watersheds as complex mixtures, with differing composition and properties that greatly influence their environmental fate, bioavailability and toxicity (ecotoxicology). Our current lack of understanding of these interactions creates considerable uncertainty when assessing environmental risk of various human activities, especially when multiple stressors are considered across watersheds. The current research program is working toward a better understanding of contaminant effects and interactions in watersheds, and the development of predictive cumulative effects frameworks that consider multiple stressors in the context of natural variability. In our past studies it has been shown that municipal wastewaters contain a large variety of chemicals that have the potential to alter physiology, metabolism and endocrine function in fish. In the Grand River watershed, wild rainbow darter (Etheostoma caeruleum) exposed to wastewater discharges caused changes across all levels of biological organization (molecular to populations). Unfortunately making linkages between specific contaminants in the environment and effects in wild fish is hampered by our poor understanding of how these diverse chemicals interact during early development to cause adverse outcomes in fish. This proposal is focused on applying controlled lab exposures of rainbow darter (eggs to adult) to specific chemicals suspected of causing effects in fish though different mechanisms (ethynylestradiol, triclosan, metformin) and contrasted to wastewater effluents (complex mixture). It will test the ability of these chemicals individually and as a mixture to cause (possibly potentiate) a variety of key changes in physiology and reproduction, including gene expression, gonad development (including intersex), sex steroid production, and behaviour. We will compliment this research with the development of a fate and effects model utilizing a decade of chemical exposure and effects data on fish in the Grand River, and the responses to recent changes in effluent quality. Finally we will initiate studies of the environmental risk of the emerging threat of novel functionalized nanoparticles (nanomedicines) that are also expected to be released into wastewater systems in the near future. The research will therefore continue to advance our understanding of important mechanisms and processes currently limiting the ability of national and international agencies to assess and manage the uncertainty and risk of this diversity of contaminants being released into our watersheds.