Hypoxia in a warming world: performance and fitness consequences of dual stressors for inland fishes

变暖世界中的缺氧：双重压力源对内陆鱼类的性能和健康影响

• 批准号: RGPIN-2020-04315
• 负责人: Chapman, Lauren
• 金额: $ 3.42万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716390
• 关键词: Hypoxia; warming; world; performance; fitness

Freshwater organisms face multiple threats associated with land conversion, pollution, and eutrophication, in addition to overharvesting and species invasions. In addition, there is mounting evidence that freshwaters are highly sensitive to climate change. Ultimately, to understand and predict effects of human activities on aquatic biodiversity, we must explore both independent and interactive effects of multiple stressors. Hypoxia (low dissolved oxygen, DO) is a widespread stressor in aquatic systems driven by influxes of wastes and fertilizers that can accelerate eutrophication; and severe hypoxia can be a powerful limiting factor on fish performance. Climate warming is likely to exacerbate hypoxia because fish metabolism and therefore oxygen demand increase with water temperature, while hypoxia limits oxygen supply. Potential interactions between these dual stressors have been the focus of several recent studies; many of which have focused on short-term (days, weeks) exposures of fish to one or both stressors. In this research program, we will quantify performance and fitness consequences of both short-term and life-long (rearing studies) exposure of fish to different temperature and DO regimes; and we will explore how fish populations from different temperature and DO regimes differ in their response. We will build on our 30-yr foundation of studies on East African fish species that cross strong gradients of temperature and DO in nature. A combination of ecophysiological assays on field populations and lab acclimation and rearing studies will be used to (a) test for oxygen dependency of upper thermal limits; (b) quantify interactive effects of hypoxia and thermal stress on performance and fitness-related traits, and (c) test whether local adaptation to hypoxia (e.g., larger gills) improves tolerance to warming waters. We will study populations crossing natural gradients of temperature and DO, and those experiencing change in DO or temperature in response to human impacts, such as deforestation that can increase water temperature or eutrophication that can decrease DO. Disentangling effects of multiple stressors is a key challenge to conservation and management of fish populations across the globe. Our long-term field system in Africa allows us to test specific predictions on independent and interactive effects of hypoxia and thermal stress on fishes based on long-term data and integrative research. By blending interpopulational studies, long-term environmental data, and rearing experiments, we will provide a much needed link between effects of dual stressors under controlled lab conditions and in nature. Consistency in field versus lab effects with strengthen our ability to predict consequences of the global hypoxia crisis in the face of climate change, and knowledge gained will help us to study and manage systems locally and abroad.

除了过度捕捞和物种入侵外，淡水生物还面临着与土地转换、污染和富营养化有关的多种威胁。此外，越来越多的证据表明，淡水对气候变化高度敏感。最终，为了理解和预测人类活动对水生生物多样性的影响，我们必须探索多种应激源的独立和交互影响。低氧(低溶解氧，DO)是水生系统中普遍存在的一种应激源，原因是废物和化肥的涌入会加速富营养化；而严重的低氧可能是鱼类性能的一个强大限制因素。气候变暖可能会加剧缺氧，因为鱼类的新陈代谢和氧气需求随着水温的升高而增加，而缺氧限制了氧气的供应。这些双重应激源之间的潜在相互作用一直是最近几项研究的焦点；其中许多研究集中在鱼对其中一种或两种应激源的短期(几天、几周)暴露。在这项研究计划中，我们将量化短期和终身(饲养研究)鱼暴露在不同温度和DO制度下的表现和适合性结果；我们将探索来自不同温度和DO制度的鱼类种群在反应上的差异。我们将建立在我们30年来对东非鱼类物种研究的基础上，这些物种跨越强烈的温度梯度，并在自然界中做到这一点。结合野外种群的生态生理分析和实验室驯化和饲养研究，将被用于：(A)测试热上限的氧依赖性；(B)量化低氧和热应激对表现和体能相关特征的交互影响；以及(C)测试局部对低氧(例如，较大的鳃)的适应是否提高了对加温水的耐受性。我们将研究跨越温度和溶解氧自然梯度的种群，以及那些经历溶解氧或温度变化以应对人类影响的种群，例如可能提高水温的森林砍伐或可能降低溶解氧的富营养化。 解开多种应激源的影响是全球鱼类种群保护和管理的关键挑战。我们在非洲的长期田间系统使我们能够在长期数据和综合研究的基础上，测试关于低氧和热应激对鱼类的独立和交互影响的具体预测。通过融合种群间研究、长期环境数据和饲养实验，我们将在受控实验室条件下的双重应激源的影响和自然界中的双重应激源之间提供亟需的联系。现场效应与实验室效应的一致性增强了我们在面对气候变化时预测全球缺氧危机后果的能力，所获得的知识将有助于我们研究和管理本地和国外的系统。