A New Ecological Framework for Adverse Outcomes of Contaminants on Ecosystems: Microplastics as a Case Study

塑料污染现在被认为是一个全球性问题。从人口密集的城市到偏远的生态系统，科学家们几乎在任何地方都发现了塑料碎片。环境中发现的大多数塑料都是微塑料，主要来自大块垃圾的分解。微塑料正在挑战我们对污染物的科学理解，因为它们既是颗粒，又是化学物质的复杂混合物。高剂量的微塑料会以各种方式伤害动物，比如阻塞肠道或释放有毒化学物质。然而，我们不知道目前的微塑料污染水平是否会对环境造成危害。我们对加拿大这个问题的了解有限，尽管最近在全国各地的河流和湖泊中发现了微塑料。在NSERC的资助下，我将研究微塑料对淡水生态系统结构和功能的影响。更简单地说，我的研究将为我们提供关于微塑料如何改变湖泊中哪些物种茁壮成长的新见解，以及这些生态系统中关键过程发生的速度有多快。这项工作是及时和相关的，因为几乎所有关于微塑料的科学评论都指出，缺乏关于这些污染物如何影响更高水平的生物组织的信息。值得注意的是，这在最近发布的加拿大塑料科学议程中得到了回应。我的研究直接解决了这个高优先级的研究需求。在这项拨款中，我建议将微塑料添加到越来越复杂的“迷你湖泊”中。从水开始，随后的实验将逐步引入微型植物，然后是小型无脊椎动物，最后是脊椎动物。这种优雅的设计使我们在一个复杂层次上学到的知识能够传递给下一个复杂层次。在我们的模型生态系统中，我们将监测社区以及关键生态系统功能的速率如何对不同程度的污染作出反应。我的研究将为加拿大的环境科学和政策做出贡献。我的研究将提供科学证据，证明微塑料是否以及如何对淡水湖和我们作为一个社会最重视的这些生态系统的特征产生负面影响。我希望我的研究能够产生有趣的假设，这将推动生态学和生态毒理学的未来研究，并支持基于证据的政策决策，以管理微塑料污染带来的潜在威胁。更广泛地说，我的项目正在开创一个新的生态框架，建立一个毒理学方法，将污染物暴露与不良后果联系起来。这样做将是一个重大的进步，因为我的领域几十年来一直在努力将“生态”纳入生态毒理学。这一框架极有可能在国际上被采用，以评估有毒化学品的环境风险。

Plastic pollution is now recognized as a global issue. Scientists have found plastic debris virtually everywhere they have looked, from densely populated cities to remote ecosystems. Most plastics found in the environment are microplastics, which primarily come from the breakdown of larger pieces of litter. Microplastics are challenging our scientific understanding of contaminants because they are both particles and a complex mix of chemicals. High doses of microplastics can harm animals in various ways, such as obstructing the gut or releasing toxic chemicals. However, we don't know if current levels of microplastic pollution are causing harm to the environment. Our knowledge of this issue in Canada is limited, despite microplastics being recently found in rivers and lakes across the country. With funding from NSERC, I will examine the effects of microplastics on structure and function of freshwater ecosystems. More simply, my research will give us new insights into how microplastics change which species thrive in lakes, as well as how quickly critical processes happen in these ecosystems. This work is timely and relevant because virtually every scientific review written about microplastics points to the lack of information on how these contaminants impact higher levels of biological organization. Notably, this was echoed in the recently released Canadian Plastics Science Agenda. My research directly addresses this high-priority research need. In this grant, I propose to add microplastics to `mini-lakes' of increasing complexity. Starting with water only, subsequent experiments will phase-in microscopic plants, followed by small invertebrates, and culminating in the addition of vertebrates. This elegant design allows what we learn at one level of complexity to inform the next. In our model ecosystems, we will monitor how the community, as well as rates of critical ecosystem functions, respond to different levels of pollution. My research will contribute to environmental science and policy in Canada. My research will generate scientific evidence as to if, and if so how, microplastics negatively impact freshwater lakes and the characteristics of these ecosystems we most value as a society. I expect my research to generate intriguing hypotheses that will drive future research in ecology and ecotoxicology and support evidence-based policy decisions for managing potential threats posed by microplastic pollution. More broadly, my program is pioneering a new ecological framework for an established toxicological approach to link contaminant exposure with adverse outcomes. Doing so would be a significant advance because my field has been struggling for decades to put the `eco' into ecotoxicology. Such a framework has strong potential to be adopted internationally to assess environmental risks of toxic chemicals.