Microbial Community Dynamics Provide Evidence for Hypoxia during a Coral Reef Mortality Event
Microbial Community Dynamics Provide Evidence for Hypoxia during a Coral Reef Mortality Event
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DOI：
10.1128/aem.00347-22
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发表时间：
2022-02
影响因子：
4.4
通讯作者：
Shawn M. Doyle;Miabel J. Self;Joseph Hayes;K. Shamberger;A. Correa;S. Davies;Lory Z. Santiago-Vázquez;J. Sylvan
中科院分区：
文献类型：
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作者：
Shawn M. Doyle;Miabel J. Self;Joseph Hayes;K. Shamberger;A. Correa;S. Davies;Lory Z. Santiago-Vázquez;J. Sylvan
2016年7月，在墨西哥湾西北部，东花园岸一小块区域内约82%的珊瑚突然死亡，没有任何预警。氧气耗尽被认为是原因。2016年7月，在德克萨斯州加尔维斯顿东南约200公里处的东花园岸发生了一次严重的珊瑚礁无脊椎动物死亡事件，其中0.06平方公里区域内约82%的珊瑚死亡。在这次死亡事件发生后不久，根据对死珊瑚和其他无脊椎动物的调查，应答者假设局部缺氧是最可能的直接原因。然而，没有可用的溶解氧数据来验证这一假设，因为在花园银行保护区内没有持续监测氧气。在这里，我们量化了浮游微生物群落的多样性，这是基于2年内在花园银行进行的四次巡航，其中包括在首次观察到死亡事件后5至8天进行的巡航。与非死亡条件下收集的观察结果相比，温跃层中浮游微生物群落的富集程度不同，已知在氧气最低区活跃和丰富的分类群或已知在死亡事件发生后不久适应氧气限制的分类群（例如SAR324， Thioglobaceae， Nitrosopelagicus和Thermoplasmata MGII）。出乎意料的是，这些富集并不局限于东岸，而是在整个研究区域普遍存在，这表明在死亡事件发生前后，温跃层中溶解氧浓度普遍减少。水文分析显示，东岸南部的珊瑚礁（局部死亡事件发生的地方）在这个时候是唯一位于温跃层内的。我们的研究结果表明，微生物群落的时间监测如何成为解决与过去环境事件相关问题的有用工具。2016年7月，在墨西哥湾西北部，东花园岸一小块区域内约82%的珊瑚突然死亡，没有任何预警。氧气耗尽被认为是原因。然而，有相当大的不确定性，因为没有从事件发生时开始的氧气数据。微生物对氧气的变化很敏感，可以作为氧气损失的生物指标。在这项研究中，我们分析了多年来在花园银行收集的水样中的微生物群落，包括在死亡事件发生后不久。我们的研究结果表明，与正常情况相比，在死亡事件期间，深水层的氧气消耗普遍存在。对水团的水文分析进一步揭示了一些低氧水可能上涌到珊瑚礁上。
In the northwestern Gulf of Mexico in July 2016, ∼82% of corals in a small area of the East Flower Garden Bank coral reef suddenly died without warning. Oxygen depletion is believed to have been the cause. ABSTRACT In July 2016, a severe coral reef invertebrate mortality event occurred approximately 200 km southeast of Galveston, Texas, at the East Flower Garden Bank, wherein ∼82% of corals in a 0.06-km2 area died. Based on surveys of dead corals and other invertebrates shortly after this mortality event, responders hypothesized that localized hypoxia was the most likely direct cause. However, no dissolved oxygen data were available to test this hypothesis, because oxygen is not continuously monitored within the Flower Garden Banks sanctuary. Here, we quantify microbial plankton community diversity based on four cruises over 2 years at the Flower Garden Banks, including a cruise just 5 to 8 days after the mortality event was first observed. In contrast with observations collected during nonmortality conditions, microbial plankton communities in the thermocline were differentially enriched with taxa known to be active and abundant in oxygen minimum zones or that have known adaptations to oxygen limitation shortly after the mortality event (e.g., SAR324, Thioglobaceae, Nitrosopelagicus, and Thermoplasmata MGII). Unexpectedly, these enrichments were not localized to the East Bank but were instead prevalent across the entire study area, suggesting there was a widespread depletion of dissolved oxygen concentrations in the thermocline around the time of the mortality event. Hydrographic analysis revealed the southern East Bank coral reef (where the localized mortality event occurred) was uniquely within the thermocline at this time. Our results demonstrate how temporal monitoring of microbial communities can be a useful tool to address questions related to past environmental events. IMPORTANCE In the northwestern Gulf of Mexico in July 2016, ∼82% of corals in a small area of the East Flower Garden Bank coral reef suddenly died without warning. Oxygen depletion is believed to have been the cause. However, there was considerable uncertainty, as no oxygen data were available from the time of the event. Microbes are sensitive to changes in oxygen and can be used as bioindicators of oxygen loss. In this study, we analyze microbial communities in water samples collected over several years at the Flower Garden Banks, including shortly after the mortality event. Our findings indicate that compared to normal conditions, oxygen depletion was widespread in the deep-water layer during the mortality event. Hydrographic analysis of water masses further revealed some of this low-oxygen water likely upwelled onto the coral reef.