Shuttle System for Evaluating Effects of Environmental Stressors on Fish Behaviour

缺氧（低溶解氧，DO）是人类对内陆和沿海水域造成压力的最严重表现之一，其原因是废物和肥料径流的流入加速了富营养化和污染。气候变化可能会加剧缺氧，因为氧的溶解度会随着温度的升高而降低，而像鱼这样的变温动物（冷血生物）的新陈代谢会增加。鱼类采用许多不同的策略来避免与缺氧有关的问题。有些反应是快速激活的（例如，几分钟，几天），而其他反应是发育可塑性和/或基因固定的。对缺氧应激的最初（快速）反应通常是行为性的（例如，回避行为），并且可能发生在远高于致死水平的DO水平。这些行为反应可以改变鱼与其环境之间的重要关系（例如，捕食者-猎物的相互作用）。鉴于世界范围内缺氧发生率的增加，我们学习预测低氧导致行为改变和生态影响的水平是至关重要的。解决这些问题的一个非常有用的途径是使用“选择”或“偏好”测试来确定生态相关的阈值。穿梭箱是由Loligo系统设计的自动化2室偏好/回避测试系统，其独特之处在于它可以严格估计DO和热偏好/回避行为以及由热应激和缺氧应激引起的行为变化的临界阈值。使用该系统，我们提出(1)量化DO/温度偏好；(2)量化缺氧和热应激如何改变行为相互作用；(3)缺氧和热应激相互作用如何改变对1-2的反应。该设备将促进国内和国际的合作和培训，其结果将直接应用于预测对缺氧（全球环境压力源）的反应及其与气候变暖（另一种普遍压力源）的相互作用。我们估计每年该系统将被至少1名PDF， 2-3名研究生，3名本科生和一名研究助理使用，从而每年有助于培养7-8名HQP。

Hypoxia (low dissolved oxygen, DO) is one of the most serious manifestations of human-induced stress to inland and coastal waters driven by influxes of wastes and fertilizer runoffs that accelerate eutrophication and pollution. Climate change may exacerbate hypoxia, because oxygen solubility decreases with rising temperature while the metabolism of ectotherms (cold-blooded organisms) like fish increases. Fishes employ many and diverse strategies to avoid problems associated with hypoxia. Some responses are activated quickly (e.g., minutes, days), whereas others are developmentally plastic and/or genetically fixed. Initial (fast) responses to hypoxic stress are often behavioural (e.g., avoidance behaviour) and may occur at DO levels far higher than lethal levels. These behavioural responses can alter crucial relationships between a fish and its environment (e.g., predator-prey interactions). Given the increasing incidence of hypoxia worldwide, it is critical that we learn to predict the levels at which low DO leads to behavioural changes and ecological effects. A very useful route to addressing these issues is the use of "choice" or "preference" tests to determine ecologically relevant thresholds. The Shuttle Box, an automated 2-compartment preference/avoidance test system designed by Loligo Systems, is unique in that it allows rigorous estimates of DO and thermal preference/avoidance behaviour and critical thresholds at which behavioural changes are induced by thermal and hypoxic stress. Using this system we propose to (1) quantify DO/temperature preference; (2) quantify how hypoxia and thermal stress modify behavioural interactions, and (3) how the responses to 1-2 are altered by the interaction of hypoxia and thermal stress. This equipment will facilitate collaboration and training both nationally and internationally, and results will have direct application to predicting response to hypoxia, a global environmental stressor, and its interaction with climate warming, another pervasive stressor. We estimate that each year this system will be used by at least 1 PDF, 2-3 graduate students, 3 undergraduates, and a research assistant, thus contributing to the training of 7-8 HQP per year.