Phytoplankton Productivity in an Arctic Fjord (West Greenland): Estimating Electron Requirements for Carbon Fixation and Oxygen Production.
Phytoplankton Productivity in an Arctic Fjord (West Greenland): Estimating Electron Requirements for Carbon Fixation and Oxygen Production.
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DOI：
10.1371/journal.pone.0133275
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Glud RN
中科院分区：
文献类型：
--
作者：
Hancke K;Dalsgaard T;Sejr MK;Markager S;Glud RN
准确量化中上层初级生产对于量化海洋碳周转和食物网的能源供应至关重要。了解碳（C）固定（K C）和氧气（O2）产生（K O2）的电子需求（K）后，可变荧光有可能量化微藻的初级生产，从而与传统方法相比提高测量的空间和时间分辨率。在这里，我们通过脉冲幅度调制 (PAM) 荧光测定、C 固定和北极峡湾（格陵兰西部 Godthåbsfjorden）的 O2 产生来量化 Κ C 和 Κ O2。通过短期（2 小时）和长期（24 小时）实验，对电子转移速率 (ETRPSII)、C 固定和/或 O2 产生进行了量化和比较。 ETR 的绝对率是通过考虑光系统 II 光吸收和光谱光成分得出的。两小时的孵育揭示了光限制光合作用期间 ETRPSII 与总 14C 固定之间的线性关系 (R2 = 0.81)，给出 Κ C 为 7.6 ± 0.6（平均值 ± S.E.）mol é (mol C)−1。 Diel 净速率还证明了 ETRPSII 和 C 固定之间的线性关系，给出 Κ C 为 11.2 ± 1.3 mol é (mol C)−1 (R2 = 0.86)。对于净 O2 产生，电子需求低于净 C 固定，为 6.5 ± 0.9 mol é (mol O2)−1 (R2 = 0.94)。然而，这仍然是 O2 生产的理论最小值的 1.6 倍高的电子需求 [即。 4 mol é (mol O2)−1]。这种差异可以通过呼吸活动和非光化学电子需求来解释，并讨论了变异性。总之，生物光学方法和衍生的电子需求支持将 ETR 转换为 C 或 O2 单位，为提高初级生产估算的空间和时间分辨率铺平了道路。
Accurate quantification of pelagic primary production is essential for quantifying the marine carbon turnover and the energy supply to the food web. Knowing the electron requirement (Κ) for carbon (C) fixation (Κ C) and oxygen (O2) production (Κ O2), variable fluorescence has the potential to quantify primary production in microalgae, and hereby increasing spatial and temporal resolution of measurements compared to traditional methods. Here we quantify Κ C and Κ O2 through measures of Pulse Amplitude Modulated (PAM) fluorometry, C fixation and O2 production in an Arctic fjord (Godthåbsfjorden, W Greenland). Through short- (2h) and long-term (24h) experiments, rates of electron transfer (ETRPSII), C fixation and/or O2 production were quantified and compared. Absolute rates of ETR were derived by accounting for Photosystem II light absorption and spectral light composition. Two-hour incubations revealed a linear relationship between ETRPSII and gross 14C fixation (R2 = 0.81) during light-limited photosynthesis, giving a Κ C of 7.6 ± 0.6 (mean ± S.E.) mol é (mol C)−1. Diel net rates also demonstrated a linear relationship between ETRPSII and C fixation giving a Κ C of 11.2 ± 1.3 mol é (mol C)−1 (R2 = 0.86). For net O2 production the electron requirement was lower than for net C fixation giving 6.5 ± 0.9 mol é (mol O2)−1 (R2 = 0.94). This, however, still is an electron requirement 1.6 times higher than the theoretical minimum for O2 production [i.e. 4 mol é (mol O2)−1]. The discrepancy is explained by respiratory activity and non-photochemical electron requirements and the variability is discussed. In conclusion, the bio-optical method and derived electron requirement support conversion of ETR to units of C or O2, paving the road for improved spatial and temporal resolution of primary production estimates.