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.

湖泊是加拿大最具特色的景观之一，也是我们对环境变化最敏感的哨兵。这些系统的压力源包括文化富营养化，栖息地丧失，物种引进和气候变化。确定单个压力源对湖泊浮游生物群落的影响通常具有挑战性，因为压力源通常是组合发生的。以前的工作表明，相互作用的压力可能包括从加性效应到更复杂的情况，其中它们相互增强（协同作用）或抑制（拮抗效应）。在这个建议中，我将使用湖泊采样的空间和时间，实验性的围隔生态系统，和建模相结合，以创建一个景观的预期反应，主要的相互作用的压力。该模型开发的主要现场将是西部伊利湖。该流域可以经历蓝藻（主要是铜绿微囊藻）在主要流入河流附近的水华梯度，而流域的其他部分则没有水华。与此同时，该盆地每年都有一个关键的引进捕食者，水蚤Bythotrephes longimanus，其丰度和影响随季节和空间而变化。主要的浮游动物群体对蓝细菌菌落的敏感性各不相同，专门的饲养者（如轮虫）几乎不受影响，而其他人，如主要的食草动物水蚤，受到了严重的负面影响这些相同的浮游动物群体也不同的脆弱性Bythotrephes摄入，轮虫不受影响和水蚤严重影响。有趣的是，伤害水蚤等食草动物种群的两种共同发生的压力可以同时对轮虫产生中性或积极的影响（由于不敏感和竞争性释放）。这些反应的复杂性表明，确定相互作用的压力源的影响将是一个具有挑战性的问题。在这项建议中，我们将评估浮游动物群落的组成和丰富的空间和季节性的发展，蓝藻水华和Bythotrephes人口，与预期的变化，在社会组成和丰富的将反映相互作用的压力敏感性。将在微囊藻和Bythotrephes密度梯度上进行围隔实验，实验室饲养的关键枝藻（水蚤）和轮虫（Keratella）的混合群落。建模练习将探索在没有压力源的情况下，以及在存在一种或两种压力源的情况下，这种混合社区之间的相互作用的性质。最后，我们将验证我们的模型，使用内陆湖泊和其他地区的五大湖的Bythotrephes人口和微囊藻水华共同发生。我们的项目将揭示相互作用的压力源的复杂性，预计共同发生的Bythotrephes和微囊藻水华蔓延到加拿大各地的更多湖泊。