Why is the South Orkney Island shelf (the world's first high seas marine protected area) a carbon immobilization hotspot?
Why is the South Orkney Island shelf (the world's first high seas marine protected area) a carbon immobilization hotspot?
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DOI：
10.1111/gcb.13157
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发表时间：
2016-03-01
影响因子：
11.6
通讯作者：
Sands, Chester J.
中科院分区：
文献类型：
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作者：
Barnes, David K. A.;Ireland, Louise;Sands, Chester J.
2010年，南大洋群岛南奥克尼群岛（SOI）成为世界上第一个完全公海海洋保护区（MPA）。SOI大陆架（约44000km（2））在冰川期不到一半被地面冰盖覆盖，生物丰富，是海面变暖和海冰损失的关键区域。人们对那里的碳循环知之甚少，但最近的研究表明，它是底栖生物碳固定（净年度碳积累）的一个非常重要的场所，是少数几个可证明的气候变化负反馈之一。SOI苔藓虫的碳固定是较高的，每种，单位面积和无冰天，比其他地方的极地。在这里，我们调查为什么碳固定在SOI如此之高，这是否是由于高密度，长寿或高年产量的苔藓虫（底栖悬浮饲料）的六个研究物种。我们比较了西南极洲周围主要地区的海底碳固定与海冰和初级生产，从遥感和直接采样的来源。最低的碳固定是在最北端的研究区域（南格鲁吉亚）和最南端的阿蒙森海。然而，年龄和密度标准化的数据显示，只有SOI是异常的（高）。SOI的高固定化是由于苔藓虫的年产量非常高（而不是高密度或寿命），分别比别林斯高晋、南格鲁吉亚和阿蒙森大陆架高2倍、3倍和5倍。我们发现，碳固定相关的浮游植物水华的持续时间（但不是峰值或综合生物量），无论是在直接采样，本地规模的数据和跨区域使用遥感数据。SOI的长期水华似乎推动了相当大的碳固定化，但整个南极洲西部的海冰损失意味着，在别林斯高晋海和阿蒙森海也可能形成显著的碳汇和对气候变化的负反馈。
The Southern Ocean archipelago, the South Orkney Islands (SOI), became the world's first entirely high seas marine protected area (MPA) in 2010. The SOI continental shelf (similar to 44000km(2)), was less than half covered by grounded ice sheet during glaciations, is biologically rich and a key area of both sea surface warming and sea-ice losses. Little was known of the carbon cycle there, but recent work showed it was a very important site of carbon immobilization (net annual carbon accumulation) by benthos, one of the few demonstrable negative feedbacks to climate change. Carbon immobilization by SOI bryozoans was higher, per species, unit area and ice-free day, than anywhere-else polar. Here, we investigate why carbon immobilization has been so high at SOI, and whether this is due to high density, longevity or high annual production in six study species of bryozoans (benthic suspension feeders). We compared benthic carbon immobilization across major regions around West Antarctica with sea-ice and primary production, from remotely sensed and directly sampled sources. Lowest carbon immobilization was at the northernmost study regions (South Georgia) and southernmost Amundsen Sea. However, data standardized for age and density showed that only SOI was anomalous (high). High immobilization at SOI was due to very high annual production of bryozoans (rather than high densities or longevity), which were 2x, 3x and 5x higher than on the Bellingshausen, South Georgia and Amundsen shelves, respectively. We found that carbon immobilization correlated to the duration (but not peak or integrated biomass) of phytoplankton blooms, both in directly sampled, local scale data and across regions using remote-sensed data. The long bloom at SOI seems to drive considerable carbon immobilization, but sea-ice losses across West Antarctica mean that significant carbon sinks and negative feedbacks to climate change could also develop in the Bellingshausen and Amundsen seas.