Hypoxia, or low dissolved oxygen (DO), is a widespread water quality problem affecting estuaries and coastal waters around the world. Water quality criteria for DO have been established for every estuary in the US and are an important part of the regulatory response to nutrient pollution and associated anthropogenic eutrophication. Experimental studies examining effects of low DO exposure have been to quantify outcomes based on hypoxia effects observed in individuals, such as increased mortality or growth impairment. Although laboratory exposure tests provide useful benchmarks for policy development, most of those considered in policy development did not consider behavioral responses to low DO. However, experimental research has shown that behavioral responses occur, and that behavior modifies exposure to low DO conditions. Here we begin development of a spatially explicit individual based model (SEIBM) intended to project behavioral outcomes of exposure to spatially variable hypoxia in estuaries. Our goal is to consider the responsiveness of an SEIBM to both different behavioral hypotheses, as well as realistic spatial patterns in hypoxia. A sensitivity analysis was used to explore responsiveness based on two movement strategies: avoidance and behavioral switching. We tested the sensitivity of a suite of movement parameters to changes in spatial patterns representative of an index estuary. The sensitivity analysis demonstrated that model responses to changes in movement strategies include biologically meaningful changes in site occupancy and movement distance centered on individual behavior near a normoxic–hypoxic boundary. Further, the model demonstrated important sensitivity to realistic changes in movement parameters, including the size and shape of the individual neighborhood describing knowledge useful for movement decisions. These results support the utility of the developed SEIBM for exploring behavioral responses of fish to hypoxia in estuaries. The sensitivity analysis also demonstrates parameter values that must be set based on empirical data and are sensitive to data quality. These results will be used to further develop the model and to plan field and laboratory studies to support model parametrization. The end goal is a model framework that can inform policy decisions regarding hypoxia resulting from anthropogenic nutrient loading in estuaries.

中文翻译：

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模拟鱼类行为反应对管理具有空间溶解氧变化的河口缺氧的影响

缺氧或低溶解氧 (DO) 是影响世界各地河口和沿海水域的普遍水质问题。美国每个河口都制定了溶解氧水质标准，这是针对营养物污染和相关人为富营养化监管响应的重要组成部分。检验低溶解氧暴露影响的实验研究是根据个体观察到的缺氧效应来量化结果，例如死亡率增加或生长障碍。尽管实验室暴露测试为政策制定提供了有用的基准，但政策制定中考虑的大多数人并没有考虑对低溶解氧的行为反应。然而，实验研究表明，行为反应会发生，并且行为会改变暴露于低溶解氧条件的情况。在这里，我们开始开发一个空间明确的基于个体的模型（SEIBM），旨在预测河口暴露于空间可变缺氧的行为结果。我们的目标是考虑 SEIBM 对不同行为假设以及缺氧情况下的现实空间模式的响应能力。敏感性分析用于探索基于两种运动策略的响应能力：回避和行为转换。我们测试了一系列运动参数对代表指数河口的空间模式变化的敏感性。敏感性分析表明，模型对运动策略变化的反应包括以常氧-低氧边界附近的个体行为为中心的场地占用和运动距离的具有生物学意义的变化。此外，该模型表现出对运动参数的实际变化的重要敏感性，包括描述对运动决策有用的知识的各个邻域的大小和形状。这些结果支持了所开发的 SEIBM 在探索河口鱼类对缺氧的行为反应方面的实用性。敏感性分析还表明必须根据经验数据设置并对数据质量敏感的参数值。这些结果将用于进一步开发模型并规划现场和实验室研究以支持模型参数化。最终目标是建立一个模型框架，可以为有关河口人为营养物负荷导致缺氧的政策决策提供信息。