Mobile Field Respirometry System for Evaluating Effects of Environmental Stressors on Fish Performance

人类活动导致的生物多样性丧失是一个重要而紧迫的科学问题。因此，提高我们理解和预测环境压力因素对表现和健康特征的影响的能力变得越来越重要。缺氧（低溶解氧，DO）是人为压力对淡水和沿海水域造成的最严重的表现之一，其原因是废物和肥料的流入加速了富营养化。而且，对于鱼类来说，严重的缺氧可能是与健身相关的表现（例如游泳）的强大限制因素。气候变暖可能会加剧缺氧，因为氧气在水中的溶解度会随着温度的升高而降低，而鱼类等变温动物（冷血生物）的新陈代谢会增加。缺氧也可能通过限制鱼类在较高温度下的有氧表现而加剧热应激的影响。鉴于缺氧和全球变暖都是普遍存在的水生应激源，解决它们的相互作用至关重要。这对热带鱼来说尤其重要，因为许多热带鱼对发展中国家的粮食安全至关重要，而且由于热窗狭窄，它们可能对气候变暖特别敏感。移动呼吸测量实验室（MRL）提供了一个独特的机会，通过我们在东非乌干达水生场所的长期（24年）DO和温度数据库，对多个物种和多个地点的鱼类性能和热耐受性进行标准化的“现场”测量。通过允许我们在多个鱼类谱系中寻找对两种普遍压力源的平行（和独特）反应模式，MRL将把我们的研究项目推向一个新的水平。MRL是一种现场兼容系统，集成了Loligo Systems （http://www.loligosystems.com）提供的呼吸测量设备和软件，安装在四轮驱动的拾取车中，带有硬化（安全）顶盖和附带的便携式室外外壳。该系统使用便携式太阳能电池板、现场发电机和电池驱动的泵来运行，使我们能够在偏远地区对鱼类进行分析，为更广泛、更有代表性的鱼类对环境压力的反应分析打开了大门。实验将量化温度敏感性和短期适应能力的标准和静息代谢率，临界氧张力和临界热最大值使用急性暴露和热驯化的组合。我们将在广泛的环境梯度中瞄准一系列系统发育遥远的鱼类，包括对该地区粮食安全至关重要的鱼类。MRL将促进国内和国际的合作和培训；我们估计每年该系统将被1名PDF， 1-2名研究生，1-2名本科生和一名研究助理使用，从而每年为培训多达6名HQP做出贡献。

Biodiversity loss in response to human activities is a critical and compelling scientific issue. It has thus become increasingly important to advance our ability to understand and predict effects of environmental stressors on performance and fitness traits. Hypoxia (low dissolved oxygen, DO) is one of the most serious manifestations of anthropogenic stress to fresh and coastal waters driven by influxes of wastes and fertilizers that accelerate eutrophication. And, for fish, severe hypoxia can be a powerful limiting factor on fitness-related performance (e.g., swimming). Climate warming may exacerbate hypoxia, because the solubility of oxygen in water decreases with rising temperature, while the metabolism of ectotherms (cold-blooded organisms) like fish increases. Hypoxia may also exacerbate effects of thermal stress by limiting aerobic performance of fish at higher temperatures. Given that hypoxia and global warming are both pervasive aquatic stressors, it is critical to address their interactive effects. This is particularly important in tropical fishes, many of which are critical to food security in the developing world, and may be particularly sensitive to climate warming given narrow thermal windows. The Mobile Respirometry Lab (MRL) offers a unique opportunity to carry out standardized “on-site” measures of fish performance and thermal tolerance across multiple species and multiple locations identified from our long-term (24-yr) data base of DO and temperature for aquatic sites in Uganda, East Africa. The MRL will move our research programs to the next level by allowing us to look for parallel (and unique) patterns of response to two pervasive stressors across multiple fish lineages. The MRL is a field-compatible system that integrates respirometry equipment and software provided by Loligo Systems (http://www.loligosystems.com) housed in a 4-wheel drive pick-up with a hardened (secure) canopy cover and an accompanying portable outdoor enclosure. This system, run using portable solar panels, a field generator, and battery-operated pumps will allow us to assay fish at remote sites, opening the door for a more widespread and representative analysis of fish response to environmental stressors. Experiments will quantify temperature sensitivity and short-term acclimation capacity of standard and resting metabolic rate, critical oxygen tension, and critical thermal maximum using a combination of acute exposures and thermal acclimations. We will target a suite of phylogenetically distant fish species across broad environmental gradients including fishes critical to food security in the region. The MRL will facilitate collaboration and training both nationally and internationally; and we estimate that each year this system will be used by 1 PDF, 1-2 graduate students, and 1-2 undergraduates, and a research assistant, thus contributing to the training of up to 6 HQP per year.