Performance and fitness consequences of hypoxia and thermal stress in fishes

如果种群数量下降，没有足够的时间适应，或者如果捕食/竞争的减少使种群能够在不适应当地条件的情况下生存，无论是自然的还是人为的环境压力都可能限制当地适应。缺氧（低溶解氧，DO）是废物和肥料流入导致内陆和沿海水域加速富营养化和污染的人为压力的一种严重和广泛表现。在严重缺氧的情况下，氧气可能是与健身相关的表现特征的一个强大限制因素，比如耐力游泳或逃离捕食者。气候变化可能加剧缺氧对鱼类的影响，因为氧溶解度随着温度升高而降低，而变温动物（冷血生物）的代谢增加。相反，缺氧可能通过限制在较高温度下的有氧运动而加剧热应激。

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.