Seagrass Recovery Following Marine Heat Wave Influences Sediment Carbon Stocks
Seagrass Recovery Following Marine Heat Wave Influences Sediment Carbon Stocks
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DOI：
10.3389/fmars.2020.576784
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发表时间：
2021-01-07
影响因子：
3.7
通讯作者：
Orth, Robert J.
中科院分区：
文献类型：
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作者：
Aoki, Lillian R.;McGlathery, Karen J.;Orth, Robert J.
在世界范围内，海草草甸积累了大量的有机碳（C），被称为“蓝色”碳，可以保持几十年到几个世纪的埋藏。然而，当海草草甸受到干扰时，这些C库存可能会被矿化，导致显著的CO2排放。海洋温度升高，热浪频率和严重程度增加，威胁着海草草甸及其沉积物蓝C。到目前为止，没有研究直接测量海草的高温对沉积物碳储量的影响。在这里，我们使用一个长期的记录，从7平方公里的沉积物C股票，恢复鳗草（Zostera滨海）草甸显示，海草枯死后，一个单一的海洋热浪（MHW）导致沉积物C的显着损失。沉积物碳的损失和再积累模式滞后于海草恢复模式。沉积物C的损失集中在草甸的中心区域，在MHW和沉积物C的20%的净损失，在接下来的3年中经历了极端的拍摄密度下降90%。然而，这种影响是不均匀的，外部草甸网站表现出很少的证据表明，拍摄下降在MHW和净增加60%的沉积物C在接下来的3年。总体而言，具有较高海草恢复率的网站保持了1.7倍的C与较低恢复率的网站相比。我们的研究表明，虽然海草蓝C容易受到MHWs的影响，但海草损失的本地化可以防止草地范围内的C损失。海草蓝C的长期（十年期及以后）稳定性取决于海草对短期扰动事件的恢复力。
Worldwide, seagrass meadows accumulate significant stocks of organic carbon (C), known as "blue" carbon, which can remain buried for decades to centuries. However, when seagrass meadows are disturbed, these C stocks may be remineralized, leading to significant CO2 emissions. Increasing ocean temperatures, and increasing frequency and severity of heat waves, threaten seagrass meadows and their sediment blue C. To date, no study has directly measured the impact of seagrass declines from high temperatures on sediment C stocks. Here, we use a long-term record of sediment C stocks from a 7-km2, restored eelgrass (Zostera marina) meadow to show that seagrass dieback following a single marine heat wave (MHW) led to significant losses of sediment C. Patterns of sediment C loss and re-accumulation lagged patterns of seagrass recovery. Sediment C losses were concentrated within the central area of the meadow, where sites experienced extreme shoot density declines of 90% during the MHW and net losses of 20% of sediment C over the following 3 years. However, this effect was not uniform; outer meadow sites showed little evidence of shoot declines during the MHW and had net increases of 60% of sediment C over the following 3 years. Overall, sites with higher seagrass recovery maintained 1.7x as much C compared to sites with lower recovery. Our study demonstrates that while seagrass blue C is vulnerable to MHWs, localization of seagrass loss can prevent meadow-wide C losses. Long-term (decadal and beyond) stability of seagrass blue C depends on seagrass resilience to short-term disturbance events.