Collaborative Research: Physical Limnology for the Parasite Ecologist

传染病是如何影响种群动态和群落相互作用的，这是水生生态学研究较少的一个方面。本文主要研究了一种常见的微寄生真菌与其寄主水蚤之间的生态相互作用及其对共存浮游动物和其猎物浮游植物的影响。PI正在合并三个学科(群落生态学、物理湖沼学和流行病学建模)来解释宿主-寄生虫动态的空间和时间模式。在建立模型的同时，正在进行比较和操控实验，以在广泛的湖泊中将物理混合与宿主-寄生虫种群动态结合起来。生态和物理混合过程的耦合通常是一个重要的目标，因为大多数水生微寄生虫与它们的动物宿主不同，不会游泳。因此，从沉积物中下沉和再悬浮寄生虫孢子可能会限制疾病在湖泊和海洋中的水平传播和传播。这项工作的动机是在水蚤自然种群中疾病爆发的季节性时间，以及不同湖泊之间流行病严重程度的显著差异，这些湖泊的形态和混合潜力不同。PI正在研究单个湖泊内宿主-寄生虫相互作用的时间动态，以及控制多个湖泊之间宿主-寄生虫结果的更广泛的物理-生物过程。实验室和现场研究正被用来对标准宿主-寄生虫模型进行参数化，并得出预测，特别是阈值效应的预测，并在整个水柱操纵实验中进行测试。对湖泊热结构、底部剪切力和湍流速度尺度的测量，结合孢子浓度的变化，使模型开发能够预测湖泊沉积物中的孢子悬浮和再悬浮。物理混合模型的输出被耦合到该模型，以预测疫情爆发的可能性。寄主和寄生虫的多世代动态正在大型围栏中进行探索，以检查一个水蚤种群内的感染对与同种生物及其浮游植物猎物的竞争相互作用的间接影响。更广泛的影响：利用这种多湖、水蚤-寄生虫系统，这项合作研究正在解决疾病流行率的自然变异及其对食物网结构的影响这一普遍现象。这项研究汇集了初级和高级教员，他们在人口和群落生态学、物理湖沼学和建模方面具有综合专业知识。其次，PI是水生生态学研究较少的领域，病原体的作用。疾病生态学是一个新兴的令人担忧的领域，尽管有大量证据表明病原体是食物链的重要组成部分，但淡水生态学家在很大程度上忽视了它们。第三，通过描述性、比较性和操纵性实验与建模相结合的方法，在多个时间和空间尺度上研究疾病生态学。该项目强调对本科生、研究生和博士后进行物理湖泊学、种群建模和社区生态学方面的培训。最后，物理湖沼学和寄生虫学方面的工作正在加强KBS(野外观测站)周围湖泊的知识基础，并直接惠及在这些系统中开展工作的多个机构的水生生态学家的研究计划。它正在为KBS的K-12教师伙伴关系项目和其他外联活动作出贡献。

How infectious diseases influence population dynamics and community interactions is an understudied aspect of aquatic ecology. This work focuses on the ecological interaction between a common microparasitic fungus and its Daphnia host species, and the consequences to coexisting zooplankton and their phytoplankton prey. The PIs are merging three disciplines (community ecology, physical limnology and epidemiological modeling) to explain spatial and temporal patterns of host-parasite dynamics. Comparative and manipulative experiments are being conducted in parallel with modeling to couple physical mixing with host-parasite population dynamics in a broad set of lakes. The coupling of ecological and physical-mixing processes is a generally important goal since most aquatic microparasites, unlike their animal hosts, do not swim. Hence, sinking and resuspension of parasite spores from the sediment may limit horizontal transmission and spread of diseases in lakes and oceans. This work is motivated by the seasonal timing of disease outbreaks in natural populations of Daphnia and the substantial variability in the severity of epidemics among lakes differing in morphometry and potential for wind mixing. The PIs are examining both the temporal dynamics of host-parasite interactions within single lakes and broader scale physical-biological processes that govern host-parasite outcome among multiple lakes. Laboratory and field studies are being used to parameterize a standard host-parasite model and derive predictions, especially of threshold effects, and tested in whole water-column manipulative experiments. Measurements of lake thermal structure, bottom shear stresses and turbulent velocity scales, in conjunction with changes in spore concentration, are enabling model development to predict spore suspension and resuspension from lake sediments. Output from the physical mixing model are coupled to the model to predict the likelihood of epidemic outbreaks. Multi-generational dynamics of host and parasite are being explored in large enclosures to examine the indirect effects of infection within one Daphnia population on competitive interactions with congeners, and their phytoplankton prey. Broader impacts: Using this multiple-lake, Daphnia-parasite system, this collaborative research is addressing the general phenomenon of natural variation in disease prevalence and its impact on the structure of food webs. This research brings together junior and senior faculty with combined expertise in population and community ecology, physical limnology and modeling. Second, the PIs are a poorly studied area of aquatic ecology, the role of pathogens. Disease ecology is an emerging area of concern, but despite substantial evidence for pathogens as important components of food web, freshwater ecologists have largely ignored them. Third, the study of disease ecology at multiple temporal and spatial scales is being approached with a combination of descriptive, comparative and manipulative experiments with modeling. The project emphasizes training of undergraduates, graduates and a postdoc at the interface of physical limnology, population modeling, and community ecology. Finally, the work on physical limnology and parasitism is enhancing the knowledge base for the lakes around KBS (a field station) and directly benefit the research programs of aquatic ecologists from multiple institutions who conduct their work in these systems. It is contributing to the K-12 teacher partnership project at KBS and to other outreach activities.