Dissolved oxygen (DO) is a critically important ecological variable, and the prevalence of marine hypoxia is expected to increase due to the combined effects of ocean warming and eutrophication. Thermal stress can co-occur with hypoxia, especially in tropical systems, and can exacerbate its effects. We examine the physical processes that are important in regulating hypoxia and temperature inversions in Bahía Almirante, a semi-enclosed tropical embayment on the Caribbean coast of Panama. A 10-yr record of observations at 7 locations within Bahía Almirante reveals seasonal temperature inversions and hypoxia at depth that often co-occur. These features are more severe and persistent in the back bay, though they occur throughout Bahía Almirante. DO reductions correspond to periods with high freshwater input, including direct precipitation, resulting in strong salinity stratification that isolates bottom waters, allowing biological oxygen demand to draw down DO. Evidence indicates that lateral advection can contribute to reoxygenation events, and the relationship between near bottom DO and bottom salinities in the mid bay and back bay is consistent with deep-water renewal as the mechanism for bottom water ventilation. These hypoxia and temperature inversion events impact the biological communities of Bahía Almirante, and the physical dynamics that regulate these coincident and persistent stressors for marine organisms are likely present in other shallow, tropical estuaries.

中文翻译：

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热带海湾的季节性缺氧和逆温

溶解氧（DO）是一个至关重要的生态变量，由于海洋变暖和富营养化的综合影响，预计海洋缺氧的流行率会增加。热应激可能与缺氧同时发生，尤其是在热带系统中，并且会加剧其影响。我们研究了在巴拿马加勒比海岸半封闭的热带海湾 Bahía Almirante 中调节缺氧和温度反转的重要物理过程。Bahía Almirante 内 7 个地点的 10 年观测记录揭示了经常同时发生的季节性温度反转和深度缺氧。这些特征在后海湾更为严重和持久，尽管它们出现在整个 Bahía Almirante。DO 减少对应于淡水输入高的时期，包括直接降水，导致强烈的盐度分层，隔离底部水，使生物需氧量降低溶解氧。有证据表明，横向平流可以促进复氧事件，中湾和后湾的近底溶解氧与底盐度之间的关系与深水更新作为底水通风的机制是一致的。这些缺氧和逆温事件影响了 Bahía Almirante 的生物群落，调节海洋生物的这些同时和持续的压力源的物理动力学可能存在于其他浅水热带河口。中湾和后湾近底溶解氧与底盐度的关系与深水更新作为底水通风的机制是一致的。这些缺氧和逆温事件影响了 Bahía Almirante 的生物群落，调节海洋生物的这些同时和持续的压力源的物理动力学可能存在于其他浅水热带河口。中湾和后湾近底溶解氧与底盐度的关系与深水更新作为底水通风的机制是一致的。这些缺氧和逆温事件影响了 Bahía Almirante 的生物群落，调节海洋生物的这些同时和持续的压力源的物理动力学可能存在于其他浅水热带河口。