Performance and fitness consequences of hypoxia and thermal stress in fishes

缺氧和热应激对鱼类的表现和健康影响

• 批准号: RGPIN-2015-06675
• 负责人: Chapman, Lauren
• 金额: $ 3.57万
• 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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614292
• 关键词: Performance; fitness; consequences; hypoxia; thermal

Environmental stress, whether natural or human-induced, may constrain local adaptation if populations decline, have not had sufficient time to adapt, or if reduced predation/competition allows populations to persist despite poor adaptation to local conditions. Hypoxia (low dissolved oxygen, DO) is a serious and widespread manifestation of anthropogenic stress to inland and coastal waters driven by influx of wastes and fertilizers that accelerate eutrophication and pollution. Under severe hypoxia, oxygen can be a powerful limiting factor on fitness-related performance traits, such as endurance swimming or escaping predators. Climate change is likely to exacerbate the impacts of hypoxia on fishes, because oxygen solubility decreases with rising temperature while metabolism of ectotherms (cold-blooded organisms) increases. Conversely, hypoxia may exacerbate thermal stress by limiting aerobic performance at higher temperatures. Our studies of East African fishes from hypoxic swamps and normoxic river/lake sites have demonstrated that DO is a strong driver of divergence among populations in traits related to oxygen uptake. In comparisons of populations from low-DO and high-DO sites we have documented larger gills, larger heads (to accommodate larger gills), and greater tolerance to hypoxia in fish from low-DO sites. Despite this strong evidence that populations are adapted to their local environments, our recent studies suggest that adaptive divergence in morpho-physiological traits may not have positive fitness consequences in low-DO fish. This research program will build on these foundational studies, integrating the morphology and physiology of fishes with their ecology and evolution to understand performance and fitness consequences of hypoxia and the interaction of hypoxia with thermal stress. We will blend field surveys across DO and temperature gradients, lab acclimation and rearing studies, and field experiments to (a) test a series of predictions on interactive effects of hypoxia and thermal stress on performance and fitness and (b) test for signatures of local adaptation to extreme hypoxia in nature. By exploring potential exceptions to expected patterns of local adaptation and quantifying interactions between hypoxia and thermal stress, we can more fully understand the ecological and evolutionary consequences of environmental stressors and identify characteristics of organisms that may facilitate persistence in extreme environments or in the face of environmental change.

如果种群数量减少，没有足够的时间适应，或者如果减少的捕食/竞争使种群尽管对当地条件的适应能力较差，但减少捕食/竞争，环境压力，无论是自然的还是人为的，都可能限制当地的适应。低氧(低溶解氧，DO)是人类对内陆和沿海水域的一种严重和普遍的应激表现，其原因是废物和化肥的大量涌入，加速了富营养化和污染。在严重缺氧的情况下，氧气可能是与健康相关的表现特征的强大限制因素，如耐力游泳或逃避捕食者。气候变化可能会加剧低氧对鱼类的影响，因为氧的溶解度随着温度的升高而下降，而外温动物(冷血生物)的新陈代谢则会增加。相反，低氧可能通过限制在较高温度下的有氧表现来加剧热应激。我们对来自低氧沼泽和常氧河流/湖泊地点的东非鱼类的研究表明，DO是种群之间在与氧气吸收相关的特征上存在差异的强大驱动因素。在对低氧和高氧地点鱼类种群的比较中，我们记录了来自低氧地点的鱼更大的鳃、更大的头(以容纳更大的鳃)，以及对低氧地点鱼类的更强的耐缺氧能力。尽管有强有力的证据表明种群适应了当地的环境，但我们最近的研究表明，形态生理特征的适应性差异可能不会对低氧鱼类产生积极的适应结果。这项研究计划将在这些基础研究的基础上，将鱼类的形态和生理学与它们的生态学和进化结合起来，以了解低氧的表现和健康后果，以及低氧和热应激的相互作用。我们将结合DO和温度梯度的现场调查，实验室驯化和饲养研究，以及现场实验，以(A)测试一系列关于低氧和热应激对运动能力和体能的交互影响的预测，以及(B)测试局部适应自然界极端低氧的特征。通过探索局部适应预期模式的潜在例外并量化低氧和热应激之间的相互作用，我们可以更充分地了解环境应激源的生态和进化后果，并识别可能有助于在极端环境中或面对环境变化时持续存在的生物体的特征。