Oxygen and carbon metabolism of Zostera muelleri across a depth gradient - Implications for resilience and blue carbon
Oxygen and carbon metabolism of Zostera muelleri across a depth gradient - Implications for resilience and blue carbon
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DOI：
10.1016/j.ecss.2017.01.005
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发表时间：
2017-03-05
影响因子：
2.8
通讯作者：
Scanes, Peter
中科院分区：
文献类型：
--
作者：
Ferguson, Angus J. P.;Gruber, Renee;Scanes, Peter
人们对海草作为“蓝碳”储存库或汇的作用，以及它们抵消大气中不断上升的二氧化碳水平的潜力越来越感兴趣。本研究测量了结缕草草甸在季节生物量最低和最大值期间跨深度梯度的碳平衡的主要方面(生物量、群落新陈代谢、溶解有机碳[DOC]通量、Seston陷阱)。在年度估计中，草甸既不是碳的汇，也不是碳的来源，赛斯顿的投入(相当于总投入的58%)被WARK和DOC的出口所平衡。以WARK EXPORT为代表的碳汇取决于WARK积累的环境的性质；如果它到达潮下沉积物，它将在每年的循环中被很大程度上重新矿化，而如果将材料出口到陆地环境，WARK可能会保留14%到26%的WARK。由于缺乏对其组成和稳定性的了解，海草渗出的DOC的命运尚不清楚；然而，许多证据表明，很大一部分DOC是矿化的。草甸的净群落代谢(NCM)是平衡的，表明光合作用产生的O2平衡了群落呼吸和/或根际还原化合物(硫和铁)的再氧化。我们认为，平衡的NCM可能是带状藻的首选状态。并可能限制它们在植物无法平衡Seston输入施加的呼吸需求的环境中出现。新陈代谢和生物量之间存在密切的耦合，这反过来又受到前120天(最能预测生物量的先行光的时间积分窗口)的先行光的强迫。新陈代谢随深度和光照的季节变化而增加，伴随着地上：地下生物量比率(AGB：BGB)的下降。这一趋势被认为是一种形态适应，它平衡了在富营养化和光梯度之间维持中性植物碳平衡的相互竞争的要求。我们的研究结果表明，藻类可能是最重要的“蓝碳”储存库(即作为生物质储备储存的碳)，因此如果海草消失，这种储存库很容易退化。皇冠版权(C)2017由爱思唯尔有限公司出版。
There is growing interest in the role that seagrasses play as 'blue carbon' stores or sinks, and their potential to offset rising CO2 levels in the atmosphere. This study measured primary aspects of the carbon balance (biomass, community metabolism, dissolved organic carbon [DOC] fluxes, seston trapping) across the depth gradient in a Zostera muelleri meadow during the seasonal biomass minimum and maximum. Over the annual estimation, the meadow was neither a sink nor source of carbon, with inputs of seston (similar to 58% of total inputs) balanced by exports of wrack and DOC. The carbon sink represented by wrack export depends on the nature of the environment where the wrack accumulates; if it reaches subtidal sediments it will largely be remineralised over the annual cycle, whereas between 14 and 26% of the wrack may be preserved if the material is exported to terrestrial environments. The fate of DOC exuded by seagrasses is unknown due to a lack of knowledge about its composition and lability; however, a number of lines of evidence suggest that a large fraction of DOC is mineralised. The net community metabolism (NCM) of the meadow was balanced, indicating that photosynthetic 02 production balanced community respiration and/or the reoxidation of reduced compounds (sulphur and iron) in the rhizosphere. We suggest that a balanced NCM may be the preferred state for Zostera spp. and may limit their occurrence in environments where plants cannot balance the respiratory demand exerted by seston inputs. There was a close coupling between metabolism and biomass, which in turn is forced by antecedent light over the preceding 120 days (the time integration window for antecedent light that best predicted biomass). Increased metabolism with depth and seasonal variation in light is accompanied by a decrease in the above ground:below ground biomass ratio (AGB:BGB). This trend is suggested to be a morphological adaptation that balances the competing requirements of maintaining a neutral plant carbon balance across enrichment and light gradients. Our results suggest that Zostera muelleri may be most important as a 'blue carbon' store (i.e. carbon stored as biomass standing stock), which is therefore vulnerable to degradation if seagrasses are lost. Crown Copyright (C) 2017 Published by Elsevier Ltd.