Hypoxia and fish: ecological and evolutionary consequences

在过去的一个世纪里，淡水生态系统由于人类的强烈改造而遭受破坏，对鱼类生物多样性造成了毁灭性的后果。淡水鱼类面临的诸多挑战之一是水中氧气短缺（缺氧）的日益严重。虽然低水平的溶解氧（DO）在以低光照和低混合为特征的水域（例如沼泽）中自然存在，但由于废物和肥料的流入加速了富营养化和污染，缺氧正变得越来越普遍。因此，了解低氧胁迫对鱼类种群的影响变得越来越重要。本研究计划旨在(1)了解缺氧胁迫对鱼类的生态和进化后果，(2)将这一认识应用于当前的保护和管理问题。我们将重点放在东非内陆水域，那里缺氧普遍存在，生物多样性保护问题严重。通过比较跨DO梯度和在不同DO条件下饲养的鱼类种群，我们可以检测对缺氧胁迫的形态学、生理学和行为的变化。在东非的维多利亚湖盆地，缺氧压力的增加与严重的富营养化有关。湖中水质的变化，加上尼罗河鲈鱼的引入，导致了许多当地鱼类的灭绝。该项目还研究了遗留物种在面对环境变化时可能促进其持久性的变化（形态，生理）。

Over the past century, freshwater ecosystems have suffered as a result of intense human modification, with devastating consequences for fish biodiversity. Of the many challenges facing freshwater fishes is the increasing occurrence of oxygen scarcity in the water (hypoxia). While low levels of dissolved oxygen (DO) occur naturally in waters characterized by low light and low mixing (e.g., swamps), hypoxia is becoming more widespread as influx of wastes and fertilizers accelerates eutrophication and pollution. It is therefore increasingly important to understand the consequences of low-oxygen stress on fish populations. This research program aims to (1) understand the ecological and evolutionary consequences of hypoxic stress for fishes, and (2) apply this understanding to current conservation and management issues. We focus on inland waters of East Africa where hypoxia is widespread and problems of biodiversity conservation are acute. By comparing fish populations that cross DO gradients and rearing fish under different DO conditions, we can detect changes in the morphology, physiology, and behaviour in response to hypoxic stress. In the Lake Victoria basin of East Africa, hypoxic stress has increased associated with severe eutrophication. Changes in water quality of the lake in conjunction with introduction of the predatory Nile perch has led to the extinction of many endemic fishes. This project also investigates changes (morphological, physiological) in remnant species that may have fostered their persistence in the face of environmental change.