Seasonal rates of benthic primary production in a Greenland fjord measured by aquatic eddy correlation
Seasonal rates of benthic primary production in a Greenland fjord measured by aquatic eddy correlation
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DOI：
10.4319/lo.2014.59.5.1555
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发表时间：
2014-09-01
影响因子：
4.5
通讯作者：
Rysgaard, Soren
中科院分区：
文献类型：
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作者：
Attard, Karl M.;Glud, Ronnie N.;Rysgaard, Soren
我们首次对格陵兰岛西南部峡湾四个浅层（3-22 m 深）底栖生境的底栖初级生产力进行了全年估计。使用非侵入性水生涡相关 (EC) 氧 (O-2) 通量方法进行原位测量。一系列高质量的多日 EC 数据集记录了全年高效的底栖光养群落的存在。春季和夏季浅水区平均自养，高达43.6 mmol O-2 m(-2) d(-1)，秋季和冬季异养或接近代谢平衡。全年测量了大量的海底总初级生产力（GPP）。春季测量到最高的 GPP 速率，高达 5.7 mmol O-2 m(-2) h(-1) (136.8 mmol O-2 m(-2) d(-1))，即使在深秋和冬季的低光照水平下（< 80 μmol 量子 m(-2) s(-1)），我们测量到的速率也高达 1.8 mmol O-2 m(-2) h(-1) (43.2 mu mol O-2 m(-2) d(-1)) 峰值辐照度期间。底栖光养群落对环境光照水平做出季节性反应，并表现出全年的高光合作用效率。冬季原位下降辐照度低至2μmol量子m(-2)s(-1)，引起自养反应，光饱和指数(I-k)低至11μmol量子m(-2)s(-1)。年时间尺度上，底栖GPP平均面积率为11.5 mol O-2 m(-2) yr(-1)，相当于峡湾30-50 m深透光区综合中上层初级生产力的1.4倍。这些结果记录了底栖光合作用在生态系统水平上的重要性，并表明在评估碳和养分预算以及北极沿海生态系统对气候变化的响应时应考虑底栖光养区室。
We present the first year-round estimates of benthic primary production at four contrasting shallow (3-22 m depth) benthic habitats in a southwest Greenland fjord. In situ measurements were performed using the noninvasive aquatic eddy-correlation (EC) oxygen (O-2) flux method. A series of high-quality multiple-day EC data sets document the presence of a year-round productive benthic phototrophic community. The shallow-water sites were on average autotrophic during the spring and summer months, up to 43.6 mmol O-2 m(-2) d(-1), and heterotrophic or close to metabolic balance during the autumn and winter. Substantial benthic gross primary production (GPP) was measured year-round. The highest GPP rates were measured during the spring, up to 5.7 mmol O-2 m(-2) h(-1) (136.8 mmol O-2 m(-2) d(-1)), and even at low light levels (< 80 mu mol quanta m(-2) s(-1)) during late autumn and winter we measured rates of up to 1.8 mmol O-2 m(-2) h(-1) (43.2 mu mol O-2 m(-2) d(-1)) during peak irradiance. The benthic phototrophic communities responded seasonally to ambient light levels and exhibited year-round high photosynthetic efficiency. In situ downwelling irradiances as low as similar to 2 mu mol quanta m(-2) s(-1) induced an autotrophic response and light saturation indices (I-k) were as low as 11 mu mol quanta m(-2) s(-1) in the winter. On an annual timescale, the average areal rate of benthic GPP was 11.5 mol O-2 m(-2) yr(-1), which is similar to 1.4 times higher than the integrated gross pelagic primary production of the similar to 30-50 m deep photic zone of the fjord. These results document the importance of benthic photosynthesis on an ecosystem level and indicate that the benthic phototrophic compartment should be accounted for when assessing carbon and nutrient budgets as well as responses of coastal Arctic ecosystems to climate change.