Benthic O2 exchange across hard-bottom substrates quantified by eddy correlation in a sub-Arctic fjord
Benthic O2 exchange across hard-bottom substrates quantified by eddy correlation in a sub-Arctic fjord
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DOI：
10.3354/meps08795
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发表时间：
2010-01-01
影响因子：
2.5
通讯作者：
Rysgaard, Soren
中科院分区：
文献类型：
--
作者：
Glud, Ronnie N.;Berg, Peter;Rysgaard, Soren
海底的氧气交换是量化底栖碳周转的关键指标。然而，技术限制使得此类测量仅限于沉积区域。尽管硬底基质在许多海岸线上很常见，但对其评估却很少。2009年春季，我们使用非侵入式涡动相关技术对西格陵兰岛的3种典型基质的原位O₂交换率进行了量化：（1）在软沉积物中，黑暗中的O₂交换平均为2.0毫摩尔/平方米·小时。该速率比微剖面测量所确定的O₂交换率高80%，但与平行的岩心培养结果无显著差异。（2）对固结的沙子和石头进行的测量显示出较高的活性，平均O₂交换率与沉积区域相似。尽管是净异养型，但底栖初级生产力平均达到27毫摩尔O₂/平方米·天，按单位面积计算，与峡湾中部的浮游总生产力相似。底栖硅藻和珊瑚红藻固定的碳被微生物有效循环利用，或被大量的底表动物摄食。（3）一个覆盖着海参的垂直峭壁也显示出较高的O₂消耗率（1.2毫摩尔/平方米·小时）。由涡动相关方法得出的O₂交换呈现出明显的短期变化，反映了多种动态控制因素的相互作用，其中最重要的是局部水动力的短期变化。总之，对硬底基质的测量揭示了活跃的底栖生物群落，它们介导了较高的碳周转率。
Oxygen exchange across the seabed is a key measure for quantifying benthic carbon turnover. However, technical limitations have restricted such measurements to sedimentary areas. Few assessments on hard-bottom substrates exist although such biotopes are frequent along many coastlines. In spring 2009, we used the non-invasive eddy correlation technique to quantify the in situ O-2 exchange rate across 3 typical substrates in West Greenland: (1) in soft sediments, the O-2 exchange in darkness averaged 2.0 mmol m(-2) h(-1). The rate exceeded the O-2 exchange quantified from microprofile measurements by 80%, but was not significantly different from parallel core incubations. (2) Measurements across consolidated sand and stones revealed a high activity with average O-2 exchange similar to that of sedimentary areas. Despite being net heterotrophic, the benthic primary production on average amounted to 27 mmol O-2 m(-2) d(-1), which per unit area is similar to the pelagic gross production of the central fjord. Carbon fixed by benthic diatoms and coralline red algae was efficiently recycled by microbes or grazed by the abundant epifauna. (3) A vertical cliff covered with sea cucumbers also revealed high O-2 consumption rates (1.2 mmol m(-2) h(-1)). The O-2 exchange derived from the eddy correlation approach exhibited pronounced short-term variability reflecting the interplay of several dynamic controls, most importantly short-term variations in local hydrodynamics. All together, measurements across hard-bottom substrates revealed active benthic communities that mediate high carbon turnover rates.