Diet and foraging-related aspects of host-parasite dynamics in freshwater systems

由寄生虫和病原体引起的新出现和再出现的传染病是加拿大和全球人类、家畜和野生动物健康的主要关切。因此，了解宿主如何抵抗和耐受寄生虫感染是至关重要的。饮食可能会影响抵抗力或耐受性，但即使是寄生的风险也会影响动物的觅食行为，从而对个体和种群产生影响。通过这种方式，寄生虫可以在不感染生物体的情况下对自然界产生重大影响，有时这种情况会以令人惊讶的方式发生。例如，最近有研究表明，各种水生动物很容易吃掉自由游动的感染阶段的寄生虫。换句话说，寄生虫不仅可能影响宿主的饮食，而且可能成为某些饮食的一部分。在我们之前以淡水生物及其寄生虫为模型系统的工作的基础上，我们将使用一套跨学科的工具和方法，通过三个特定的相关主题来研究宿主和寄生虫基于饮食的相互作用，作为水生疾病生态学长期计划的一部分。鉴于目前和预计的全球环境变化将改变水生生境，包括食物供应和寄生虫数量，这可能对宿主饮食和寄生虫消费产生影响，值得考虑，以便更好地预测和管理传染病的后果。

Emerging and re-emerging infectious diseases caused by parasites and pathogens are of major concern for the health of humans, domestic animals, and wildlife in Canada and globally. It is thus vital to understand how hosts can resist and tolerate parasitic infections. Diet may influence resistance or tolerance, but even the risk of parasitism can affect foraging behaviour in animals, with consequences for individuals and populations. In this way, parasites could have significant influences in nature without ever infecting an organism, and sometimes this occurs in surprising ways. For instance, it has recently been shown that various aquatic animals readily consume the free-swimming infectious stages of helminth parasites. In other words, parasites do not just potentially affect host diets, but can be a part of some diets. Building upon our previous work with freshwater organisms and their helminth parasites as a model system, we will use a suite of interdisciplinary tools and approaches to study diet-based interactions of hosts and parasites through three specific related themes as part of a long-term program in aquatic disease ecology. Given current and projected world-wide environmental changes that will alter aquatic habitats, including food availability and parasite abundance, this may have consequences for host diets and parasite consumption which merit consideration in order to better predict and manage infectious disease outcomes. 1) Importance of host diet for resistance and tolerance to parasite infection Focusing on dietary antioxidants and essential lipids available to animals in aquatic habitats by eating algae and plants, we will examine how these affect host-parasite dynamics. This has important implications for understanding the ability of animals to defend themselves if particular dietary compounds are available, but also for parasite transmission. 2) Consumption of parasite infectious stages If free-living infectious stages are consumed, this can reduce transmission to other hosts. Identifying key consumers and the range of infectious stages they will eat, along with quantifying such removal, is therefore essential for understanding the potential scope for reduced transmission in this way. If such consumption is common, and parasites contribute substantially to the diets of some aquatic animals, it is also important to determine how they meet consumer energetic and nutritional needs. 3) Alterations in foraging behaviour under the risk of parasitism Finding food is a critical activity that takes up a lot of time and energy for most animals. If the risk of becoming infected causes animals to change their foraging behaviour in sub-optimal ways, this could have significant consequences for their ability to meet their needs. We will examine the extent to which aquatic animals alter their foraging based on specific risk.