Gulf Stream Ring Water Intrusion on the Mid-Atlantic Bight Continental Shelf Break Affects Microbially Driven Carbon Cycling
Gulf Stream Ring Water Intrusion on the Mid-Atlantic Bight Continental Shelf Break Affects Microbially Driven Carbon Cycling
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DOI：
10.3389/fmars.2019.00394
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发表时间：
2019-07
影响因子：
3.7
通讯作者：
A. Hoarfrost;J. Balmonte;S. Ghobrial;Kai Ziervogel;J. Bane;G. Gawarkiewicz;C. Arnosti
中科院分区：
文献类型：
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作者：
A. Hoarfrost;J. Balmonte;S. Ghobrial;Kai Ziervogel;J. Bane;G. Gawarkiewicz;C. Arnosti
从墨西哥湾流中分离出来的温核反气旋环在大西洋中部海湾的直接近海区域循环。如果一个温暖的核心环到达大陆架断裂，其温暖的、高盐度的水可能会淹没在更凉爽、更新鲜的大陆架表层水之下，导致陆架断裂处和上大陆坡的地下水具有高温和盐度，以及墨西哥湾流水独特的物理和化学性质。这种入侵的水还可能具有具有不同功能的微生物群落，这反过来可能会影响这种沿海/陆架环境中碳循环的速度和性质。然而，环状入侵水域内微生物群落相对于周围大陆架水域的功能能力在很大程度上尚未得到探索。我们通过测量横跨中大西洋海湾陆架、陆架断裂和上坡的横断面上一套多糖、多肽和葡萄糖底物的水解度，研究了微生物群落启动有机质再矿化的能力。在最外层的采样点，来自墨西哥湾流暖核环的温暖和咸水出现在水柱的下部。这些水表现出不同于其他采样点的水解力，并且总体上表现出较低的异养细菌生产力。近几年来，大西洋中部海湾陆架附近的暖核环出现的频率和持续时间都有所增加。随着未来暖核环对大陆架和陆坡的影响加大，大陆架上有机质再矿化的速度和性质也可能发生变化。
Warm core, anticyclonic rings that spin off from the Gulf Stream circulate through the region directly offshore of the Mid-Atlantic Bight. If a warm core ring reaches the continental shelf break, its warm, highly saline water may subduct under cooler, fresher continental shelf surface water, resulting in subsurface waters at the shelf break and over the upper continental slope with high temperatures and salinities and distinct physical and chemical properties characteristic of Gulf Stream water. Such intruding water may also have microbial communities with distinct functional capacities, which may in turn affect the rate and nature of carbon cycling in this coastal/shelf environment. However, the functional capabilities of microbial communities within ring intrusion waters relative to surrounding continental shelf waters are largely unexplored. We investigated microbial community capacity to initiate organic matter remineralization by measuring hydrolysis of a suite of polysaccharide, peptide, and glucose substrates along a transect oriented across the Mid-Atlantic Bight shelf, shelf break, and upper slope. At the outermost sampling site, warm and salty water derived from a Gulf Stream warm core ring was present in the lower portion of the water column. This water exhibited hydrolytic capacities distinct from other sampling sites, and exhibited lower heterotrophic bacterial productivity overall. Warm core rings adjacent to the Mid-Atlantic Bight shelf have increased in frequency and duration in recent years. As the influence of warm core rings on the continental shelf and slope increases in the future, the rate and nature of organic matter remineralization on the continental shelf may also shift.