Assessing interacting stressors in lakes

评估湖泊中相互作用的压力源

• 批准号: RGPIN-2022-03173
• 负责人: MacIsaac, Hugh
• 金额: $ 4.01万
• 依托单位: University of Windsor
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=755163
• 关键词: Assessing; interacting; stressors; lakes

Lakes are among Canada's most defining landscapes and most our sensitive sentinels of environmental change. Stressors of these systems include cultural eutrophication, habitat loss, species introductions, and climate change. Identifying the impact of an individual stressor on a lake's plankton community is often challenging because stressors commonly occur in combination. Previous work identified that interacting stressors may encompass everything from additive effects to more complex situations in which they enhance (synergism) or damp one another (antagonistic effects). In this proposal I will use a combination of lake sampling over space and time, experimental mesocosms, and modeling to create a landscape of expected responses to major interacting stressors. The main field site for development of the model will be western Lake Erie. This basin can experience gradients in cyanobacteria (mainly Microcystis aeruginosa) blooms near major inflowing rivers that foster blooms while other sections of the basin are bloom-free. At the same time, the basin experiences annual development of a key introduced predator, the waterflea Bythotrephes longimanus, whose abundance and impact vary seasonally and spatially. Major zooplankton groups vary with respect to sensitivity to presence of cyanobacteria colonies, with specialist feeders (e.g. rotifers) little affected, while others, like the major herbivore Daphnia spp., are strongly and negatively impacted. These same zooplankton groups also vary with respect to vulnerability to ingestion by Bythotrephes, with rotifers not affected and Daphnia heavily impacted. Interestingly, then, the same two co-occurring stressors that harm populations of grazers like Daphnia could simultaneously either neutrally or positively affect rotifers (owing to insensitivity and competitive release). The complexity of these responses indicates that defining the impact of interacting stressors will be a challenging problem. In this proposal we will assess zooplankton community composition and abundance spatially and seasonally in conjunction with development of cyanobacteria blooms and Bythotrephes populations, with the expectation that shifts in community composition and abundance will reflect sensitivity to the interacting stressors. Mesocosm experiments will be conducted across a gradient of Microcystis and Bythotrephes densities with lab-reared mixed community of a key cladoceran (Daphnia) and rotifers (Keratella). Modeling exercises will explore the nature of the interactions between this mixed community in the absence of stressors, and with one or both stressors present. Finally, we will validate our models using inland lakes and other areas of the Great Lakes where both Bythotrephes populations and Microcystis blooms co-occur. Our projects will shed light on the complexity of interacting stressors that are expected as co-occurring Bythotrephes and Microcystis blooms spread to more lakes across Canada.

湖泊是加拿大最具定义的景观之一，也是我们大多数敏感的环境变化前哨。这些系统的压力包括文化富营养化，栖息地丧失，物种引入和气候变化。由于通常结合发生压力源，因此通常会挑战确定个体压力源对湖泊浮游生物社区的影响。先前的工作表明，相互作用的压力源可能包含从添加效应到更复杂的情况，在这些情况下它们增强（协同作用）或互相抑制（拮抗作用）。在此提案中，我将在空间和时间，实验性中心和建模上使用湖泊采样的结合，以创建对主要相互作用应激源的预期响应的景观。该模型开发的主要现场将是伊利湖西部。该盆地可以在主要流入的河流附近体验蓝细菌（主要是微囊藻）血液，这些河流促进血液，而其他盆地的其他部分则没有开花。同时，盆地经历了关键引入的捕食者，水流旁路longimanus的年度发展，其丰富性和影响季节性和经常变化。主要的浮游动物组因对蓝细菌菌落的敏感性而有所不同，专家喂食器（例如旋转液）受到的影响很小，而像主要的草食动物达夫尼亚属属的其他人则受到强烈和负面影响。这些相同的浮游动物组也随着副脉摄入的脆弱性而有所不同，绳索不受影响，达芙妮（Daphnia）受到严重影响。有趣的是，那么，损害像水仙这样的放牧者种群的两个同时发生的压力源可能只是中立或积极地影响绳索（由于不敏感和竞争性释放）。这些反应的复杂性表明，在本提案中定义浮游动物社区组成和抽象在空间和季节性上评估，并结合氰基细菌血液和旁足种群的发展，期望社区组成和抽象的转移将反映对相互作用压力的敏感性。中验实验将跨微囊藻梯度和旁足密度进行，具有关键cladoceran（daphnia）和rotifers（keratella）的实验室混合群落。建模练习将探索在没有压力源的情况下以及存在一个或两个压力源的情况下，这种混合社区之间相互作用的性质。最后，我们将使用内陆湖泊和大湖区的其他区域验证我们的模型，那里的旁路种群和微囊血液共发生。我们的项目将阐明相互作用的压力源的复杂性，这些压力源被期望，这些压力源是同时发生的旁路和微囊血液，传播到加拿大更多湖泊。