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次出现的传染病是加拿大和全球对人类、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容忍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，但即使是寄生虫的风险也会影响动物的觅食行为，对个人和种群造成后果。通过这种方式，寄生虫可以在不感染有机体的情况下对自然界产生重大影响，有时这种影响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蠕虫寄生虫的自由游动感染阶段。换句话说，寄生虫不仅潜在地影响宿主的饮食，而且可能是某些饮食的一部分。在我们之前以淡水生物及其蠕虫寄生虫为模型系统的基础上，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之间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丰度，这可能会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后果。 1)寄主饮食对于抵抗和耐受寄生虫感染的重要性 我们将重点关注通过吃藻类和植物来获得水生栖息地动物可获得的饮食抗氧化剂和基本脂质，我们将研究它们如何影响宿主-寄生虫的动态。这对于理解动物的自卫能力(如果有特定的饮食化合物可用)以及寄生虫传播具有重要意义。 2)寄生虫感染阶段的消耗 如果消耗了自由生活的感染阶段，这可以减少对其他宿主的传播。因此，确定主要消费者和他们将食用的感染阶段的范围，以及量化这种清除，对于了解以这种方式减少传播的潜在范围至关重要。如果这种消费很常见，而且寄生虫对一些水生动物的饮食有很大贡献，那么确定它们如何满足消费者的能量和营养需求也是很重要的。 3)寄生风险下觅食行为的改变 对于大多数动物来说，寻找食物是一项关键的活动，需要花费大量的时间和精力。如果被感染的风险导致动物以不太理想的方式改变它们的觅食行为，这可能会对它们满足需求的能力产生重大影响。我们将研究水生动物根据特定风险改变觅食的程度。

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.