We sought to investigate the impacts of nutrient loading, warming, and open-water boundary exchanges on a shallow estuary through idealized numerical model experiments. We performed these simulations using a stand-alone implementation of the Regional Ocean Modeling System-Row-Column AESOP biogeochemical model in the Chester River estuary, a tributary estuary within the Chesapeake Bay estuarine complex. We found that metabolic rates were elevated in the shallow tributary creeks of the estuary relative to open waters and that rates of gross primary production, respiration, and net ecosystem metabolism were a function of both water temperature and local phytoplankton biomass. Warming 0.75°C and 1.25°C led to reductions in dissolved oxygen concentrations throughout the estuary. Reductions (50%) in dissolved nitrogen and phosphorus loading did not substantially alter hypoxic volumes in this turbid, nutrient-rich estuary, but warming increased hypoxic volumes by 20%–30%. Alterations of the open-water boundary that represent improved oxygen concentrations in the adjacent Chesapeake Bay mainstem led to more substantial relief of hypoxia in model simulations than nutrient reductions (~50% reductions in hypoxia). These simulations reveal the complex interplay of watershed nutrient inputs and horizontal exchange in a small tributary estuary, including the finding that future warming and nutrient reduction effects on Chesapeake Bay hypoxia will be translated to some tributary estuaries like the Chester River.

中文翻译：

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模拟营养负荷、变暖和边界交换对浅河口生态系统缺氧和代谢的影响

我们试图通过理想化的数值模型实验来研究养分负荷、变暖和开放水域边界交换对浅河口的影响。我们使用独立实施的区域海洋建模系统-行-列 AESOP 生物地球化学模型在切斯特河河口进行了这些模拟，切斯特河河口是切萨皮克湾河口综合体内的一个支流河口。我们发现，相对于开阔水域，河口浅支流的代谢率升高，初级生产总值、呼吸作用和生态系统净代谢率是水温和当地浮游植物生物量的函数。升温 0.75°C 和 1.25°C 导致整个河口溶解氧浓度降低。溶解氮和磷负荷的减少 (50%) 并没有显着改变这个浑浊、营养丰富的河口的缺氧量，但变暖使缺氧量增加了 20%–30%。代表相邻切萨皮克湾干流中氧气浓度提高的开放水域边界的改变导致模型模拟中缺氧的缓解比营养减少（缺氧减少约 50%）更显着。这些模拟揭示了小支流河口流域养分输入和水平交换之间复杂的相互作用，包括发现未来变暖和养分减少对切萨皮克湾缺氧的影响将转化为一些支流河口，如切斯特河。代表相邻切萨皮克湾干流中氧气浓度提高的开放水域边界的改变导致模型模拟中缺氧的缓解比营养减少（缺氧减少约 50%）更显着。这些模拟揭示了小支流河口流域养分输入和水平交换之间复杂的相互作用，包括发现未来变暖和养分减少对切萨皮克湾缺氧的影响将转化为一些支流河口，如切斯特河。代表相邻切萨皮克湾干流中氧气浓度提高的开放水域边界的改变导致模型模拟中缺氧的缓解比营养减少（缺氧减少约 50%）更显着。这些模拟揭示了小支流河口流域养分输入和水平交换之间复杂的相互作用，包括发现未来变暖和养分减少对切萨皮克湾缺氧的影响将转化为一些支流河口，如切斯特河。