Trophic interactions and contaminant exposures under climate-driven species redistribution

全球变化引起的物种相互作用的变化，如资源竞争和捕食，可能对野生动物种群和整个生态系统产生深远但不可预测的影响。生态学理论认为，关键物种可能是气候变化的“生物倍增器”，这些物种可能以顶级捕食者的形式出现。顶级捕食者对全球变化高度敏感，并对猎物种群造成自上而下的影响。由于它们处于营养顶端，这些捕食者也会在整个食物网中产生影响，例如，化学污染物的营养放大。因此，通过对快速变化的北极地区的顶级捕食者的研究，我将解决这个研究项目的长期目标，即回答这个问题：本地物种和向北重新分布的非本地物种之间的主要种间相互作用是什么？这些相互作用如何形成对环境压力源（特别是污染物、病原体和寄生虫）的暴露和影响？在接下来的五年里，我的研究小组将通过三个短期目标来回答这个问题，分别关注北极两种主要顶级捕食者的竞争、污染物暴露和捕食，分别：(1)确定北极原生海洋顶级捕食者和再分布的亚北极海洋顶级捕食者之间的捕食生态位宽度和重叠；(2)在这两种捕食者中，评估新型营养相互作用对污染物暴露（即生物放大）的比较影响；(3)建立并实施定量模型，估算北极海洋生态系统原生和新型顶端捕食者饮食中本地和非本地猎物物种的组成。了解不断变化的物种关系和压力源暴露将为未来全球变化下的人口和群落预测提供可靠的模型。由于减轻影响取决于预测未来结果的能力，结果将有助于提高加拿大及其他地区海洋生物自然资源的可持续性。研究结果还将支持联邦政府对联合国污染物协议的监测要求。最后，研究结果将通过评估不断变化的国家食品篮子和污染物负荷，从而评估野生食品对北方社区的健康益处，从而提高对传统海洋食品安全和安全的认识。

Global change-induced shifts in species interactions, such as resource competition and predation, may have profound but unpredictable impacts on wildlife populations and whole ecosystems. Ecological theory suggests that key species may act as “biotic multipliers” of climate change and that these species are likely to take the form of top predators. Top predators are highly sensitive to global change and cause top-down impacts on prey populations. Given their apex trophic position, such predators also accrue effects occurring throughout the food web, e.g., trophic magnification of chemical pollutants. Thus, through studies on apex predators in a rapidly transforming Arctic, I will address the long-term objective of this research program, which is to answer the question: what are the key interspecific interactions of native and northward-redistributing non-native species and how do these interactions shape exposures to, and effects of, environmental stressors, particularly pollutants, pathogens, and parasites? In the next five years, my research group will work towards answering this question by focussing on competition, pollutant exposures, and predation in two key apex predators in the Arctic through three short-term objectives, respectively: (1) determine feeding niche breadth and overlap between the native Arctic marine top predator and the redistributing sub-Arctic marine top predator; (2) assess the comparative influence of novel trophic interactions on pollutant exposure, i.e., biomagnification, in these two predators; and (3) develop and implement quantitative models to estimate composition of native and non-native prey species in the diets of the native and new apex predator of Arctic marine ecosystems. Understanding changing species relationships and stressor exposures will inform robust models of population and community projections under future global change. As mitigation of impacts relies on ability to predict future outcomes, results will contribute to improved sustainability of living marine natural resources in Canada and beyond. Results will also support federal monitoring requirements for United Nations agreements on pollutants. Lastly, findings will improve knowledge on the security and safety of traditional marine foods by evaluating shifting country food baskets and contaminant loads, and thus the health benefits of wild foods for Northern communities.