Photoacclimation Responses in Subarctic Atlantic Phytoplankton Following a Natural Mixing-Restratification Event
Photoacclimation Responses in Subarctic Atlantic Phytoplankton Following a Natural Mixing-Restratification Event
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DOI：
10.3389/fmars.2018.00209
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发表时间：
2018-06-14
影响因子：
3.7
通讯作者：
Behrenfeld, Michael J.
中科院分区：
文献类型：
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作者：
Graff, Jason R.;Behrenfeld, Michael J.
表层海洋中强烈的物理扰动垂直地重新分布浮游生物，并导致生物与其生长环境之间的新关系。浮游植物携带到更深的深处减少了光暴露，而分层使表面混合层中的细胞暴露在更高的光下。浮游植物可以利用光驯化过程，如非光化学猝灭和色素和其他大分子的变化，对生长照度(例如)的变化做出快速反应。虽然在实验室中观察光生理对生长光照变化的反应是很常见的，但很少有研究能够在拉格朗日框架下记录田间的这些过程。我们能够跟踪一个自然浮游植物群落4天，并在亚北极大西洋发生深度混合和再分层事件后，观察到快速的光生理反应和低至200米的生物量净积累模式。应用流式细胞术和快速重复荧光法(FRRf)，我们报道了多个分类类群与快速进化的物理环境有关的光驯化反应。在深层夹带事件之后发生了显著的层结，将细胞隔离在活跃的混合和浅化的表层、较低的真光层和光层以下。在这些不同的光历史的深度之间，积累和光适应的模式明显不同。聚球藻、微真核生物和纳米真核生物群体之间的光适应模式大体上是一致的，但光适应范围的差异和差异表明了不同的生理学。在散装海水上收集的连续FRRf测量结果表明，光系统II反应中心的数量减少，功能截面同时增加，这意味着维持整个混合层的光合作用速率。了解群体的特定差异以及群体适应策略对于根据光驯化参数确定生长和积累速率以及净初级生产力的模型将是重要的。更重要的是，细胞适应风暴事件的频率和空间动态的速率，如这里记录的那样，直接影响在不平衡增长的背景下对浮游植物叶绿素、碳及其比率的远程反演的解释和应用。
Strong physical disturbances in the surface ocean vertically redistribute plankton and lead to new relationships between organisms and their growth environment. Entrainment of phytoplankton to deeper depths decreases light exposure while stratification exposes cells in the surface mixing layer to higher light. Phytoplankton can rapidly respond to alterations in growth irradiance (Eg) using photoacclimation processes such as nonphotochemical quenching and alterations in pigments and other macromolecules. While it is common to observe photophysiological responses to shifts in growth irradiance in the laboratory it is rare that a study is able to document these processes in the field in a lagrangian framework. We were able to follow a natural phytoplankton community for 4 days and observe rapid photophysiological responses and net accumulation patterns of biomass down to 200 m following a deep mixing and restratification event in the subarctic Atlantic ocean. Applying flow cytometry and fast rate repetition fluorometry (FRRf) we report on the photoacclimation responses of multiple taxonomic groups in relation to the rapidly evolving physical environment. Significant stratification occurred following the deep entrainment event, isolating cells within an actively mixing and shoaling surface layer, the lower euphotic zone, and below the photic zone. Distinct differences in patterns of accumulation and photoacclimation are apparent between these depths of disparate light histories. Photoacclimation patterns are generally consistent between Synechococcus, picoeukaryote, and nanoeukaryote groups yet diel patterns and variability in the range of photoacclimation suggest divergent physiology. Results from continuous FRRf measurements collected on bulk seawater show a decrease in the number of photosystem II reaction centers and a concurrent increase in the functional cross section with implications for maintaining photosynthetic rates throughout the mixed layer. Understanding group specific differences as well as bulk community acclimation strategies will be important for informing models relying on photoacclimation parameters to determine growth and accumulation rates and net primary production. More so, the rates at which cells acclimate within the context of the frequency and spatial dynamics of storm events, such as the one recorded here, directly impact interpretations and applications of remote retrievals of phytoplankton chlorophyll, carbon, and their ratio in the context of unbalanced growth.