Satellite-detected fluorescence: Decoupling nonphotochemical quenching from iron stress signals in the South Atlantic and Southern Ocean
Satellite-detected fluorescence: Decoupling nonphotochemical quenching from iron stress signals in the South Atlantic and Southern Ocean
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DOI：
10.1002/2013gb004773
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发表时间：
2014-05-01
影响因子：
5.2
通讯作者：
Moore, C. M.
中科院分区：
文献类型：
--
作者：
Browning, T. J.;Bouman, H. A.;Moore, C. M.
卫星探测到的阳光诱导的叶绿素荧光可以提供有关全球范围内浮游植物生理状况的宝贵信息。在对可能影响卫星信号的多种生态生理过程进行反卷积时，存在相当大的不确定性，这使实现这一潜力受到了干扰。目前不确定的一个主要来源是，当捕获卫星图像时，浮游植物通常暴露在高强度光下，造成叶绿素荧光减少的程度。在这项研究中，在从亚热带环流到南大洋水域的游轮上进行的200多次非光化学猝灭（NPQ）实验的结果证实，卫星荧光量子产率有可能揭示铁（Fe）应力的广泛区域。然而，我们的研究结果表明，浮游植物的NPQ行为在不同的海洋环境中存在显著的差异。因此，必须考虑动态NPQ，以便根据铁应力实现对卫星荧光的可靠解释。具体而言，分层副热带环流型水域的NPQ明显低于混合良好的南大洋水域。这种变化可能是由于浮游植物所经历的入射辐照度波动的差异造成的，高度变化的辐照条件可能驱使浮游植物适应或适应更高的动态NPQ能力。经验表明，海面温度与NPQ参数的相关性最强，并被认为是校正所研究区域叶绿素荧光特征的一种手段。通过这些校正，提出了南大洋夏季卫星观测的年代际复合资料，可能反映了铁应力分布和程度的空间变异性。
Satellite-detected sunlight-induced chlorophyll fluorescence could offer valuable information about the physiological status of phytoplankton on a global scale. Realization of this potential is confounded by the considerable uncertainty that exists in deconvolving the multiple ecophysiological processes that can influence the satellite signal. A dominant source of current uncertainty arises from the extent of reductions in chlorophyll fluorescence caused by the high light intensities phytoplankton are typically exposed to when satellite images are captured. In this study, results from over 200 nonphotochemical quenching (NPQ) experiments conducted on cruises spanning from subtropical gyre to Southern Ocean waters have confirmed that satellite fluorescence quantum yields have the potential to reveal broad regions of iron (Fe) stress. However, our results suggest significant variability in phytoplankton NPQ behavior between oceanic regimes. Dynamic NPQ must therefore be considered to achieve a reliable interpretation of satellite fluorescence in terms of Fe stress. Specifically, significantly lower NPQ was found in stratified subtropical gyre-type waters than in well-mixed Southern Ocean waters. Such variability is suggested to result from differences in incident irradiance fluctuation experienced by phytoplankton, with highly variable irradiance conditions likely driving phytoplankton to acclimate or adapt toward a higher dynamic NPQ capacity. Sea surface temperature empirically demonstrated the strongest correlation with NPQ parameters and is presented as a means of correcting the chlorophyll fluorescence signature for the region studied. With these corrections, a decadal composite of satellite austral summer observations is presented for the Southern Ocean, potentially reflecting spatial variability in the distribution and extent of Fe stress.