Oyster reefs as carbon sources and sinks
Oyster reefs as carbon sources and sinks
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DOI：
10.1098/rspb.2017.0891
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发表时间：
2017-07-26
影响因子：
4.7
通讯作者：
Ridge, Justin T.
中科院分区：
文献类型：
--
作者：
Fodrie, F. Joel;Rodriguez, Antonio B.;Ridge, Justin T.
碳掩埋作为一种由受威胁的沿海植被生境提供的服务，越来越受到重视。同样，贝类珊瑚礁含有大量的碳库，在全球范围内濒临灭绝，但贝类珊瑚礁作为大气CO2的源（+）或汇（2）的作用仍然存在相当大的不确定性。虽然CO2释放是碳酸盐贝壳生产（然后埋葬）的副产品，但贝类也通过过滤和固定碳的初级生产者的快速生物沉积促进大气CO2下降。我们提供了一个框架来解释无机碳和有机碳的双重埋藏，并证明了潮间带滩涂上十年的实验珊瑚礁是CO2的净来源（7.1 +/- 1.2 MgC ha（-1）yr（-1）（mu + s.e.））主要由碳酸盐沉积造成，而浅潮下礁（-1.0 +/- 0.4 MgC ha（-1）yr（-1））和盐沼边缘礁（-1.3 +/- 0.4 MgC ha（-1）yr（-1））主要由富含有机碳的沉积物组成，并作为净碳汇（与植被沿海栖息地相当）。这些贝类水平的差异反映了贝类生长、生存和贝壳生物侵蚀的梯度。值得注意的是，在100至4000岁的珊瑚礁反映实验珊瑚礁的数据，表明我们的结果是相关的百年至千年尺度，虽然我们注意到，这些天然珊瑚礁似乎作为轻微的碳源（0.5 +/- 0.3 MgC公顷（-1）年（-1））。在全球范围内，历史上对贝类礁顶米的开采可能已将超过4亿毫克的有机碳重新引入河口。重要的是，珊瑚礁的形成和破坏不会对大气中的二氧化碳产生相互抵消的影响，因为挖掘出的有机物质可能会被矿化，而贝壳可能会通过重新掩埋而继续保存。因此，可将保护现有珊瑚礁视为侧重于沿海地区的气候减缓方案的一个组成部分。
Carbon burial is increasingly valued as a service provided by threatened vegetated coastal habitats. Similarly, shellfish reefs contain significant pools of carbon and are globally endangered, yet considerable uncertainty remains regarding shellfish reefs' role as sources (+) or sinks (2) of atmospheric CO2. While CO2 release is a by-product of carbonate shell production (then burial), shellfish also facilitate atmospheric-CO2 drawdown via filtration and rapid biodeposition of carbon-fixing primary producers. We provide a framework to account for the dual burial of inorganic and organic carbon, and demonstrate that decade-old experimental reefs on intertidal sandflats were net sources of CO2 (7.1 +/- 1.2 MgC ha(-1) yr(-1) (mu + s.e.)) resulting from predominantly carbonate deposition, whereas shallow subtidal reefs (-1.0 +/- 0.4 MgC ha(-1) yr(-1)) and saltmarsh-fringing reefs (-1.3 +/- 0.4 MgC ha(-1) yr(-1)) were dominated by organic-carbon-rich sediments and functioned as net carbon sinks (on par with vegetated coastal habitats). These landscape-level differences reflect gradients in shellfish growth, survivorship and shell bioerosion. Notably, down-core carbon concentrations in 100- to 4000-year-old reefs mirrored experimental-reef data, suggesting our results are relevant over centennial to millennial scales, although we note that these natural reefs appeared to function as slight carbon sources (0.5 +/- 0.3 MgC ha(-1) yr(-1)). Globally, the historical mining of the top metre of shellfish reefs may have reintroduced more than 400 000 000 Mg of organic carbon into estuaries. Importantly, reef formation and destruction do not have reciprocal, counterbalancing impacts on atmospheric CO2 since excavated organic material may be remineralized while shell may experience continued preservation through reburial. Thus, protection of existing reefs could be considered as one component of climate mitigation programmes focused on the coastal zone.