Episodic deep mixing events are one component of the biological carbon pump that physically transports organic carbon into the mesopelagic. Episodic deep mixing also disrupts summertime thermal stratification thereby changing the light field and nutrient concentrations available for phytoplankton growth. Phytoplankton survival and growth below the mixed layer following restratification depends on how rapidly cells can employ a variety of photoacclimation processes in response to the environmental changes. To compare the relative timescales of summertime episodic deep mixing events with the timescales of phytoplankton photoacclimation processes, we first analyzed autonomous float data to survey the frequency and magnitude of deep mixing events in the western North Atlantic Ocean. Next, we simulated a sustained deep mixing event in the laboratory and measured rates of acclimation processes ranging from light harvesting to growth in a model diatom and green alga. In both algae increases in chlorophyll (Chl) were coupled to growth, but growth of the green alga lagged the diatom by about a day. In float profiles, significant increases in Chl and phytoplankton carbon (C_phyto) were detected below the mixed layer following episodic deep mixing events. These events pose a previously unrecognized source of new production below the mixed layer that can significantly boost the amount of carbon available for export to the deep ocean.

中文翻译：

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间歇性深层混合过程中的快速光适应增加了生物碳泵

间歇性深层混合事件是生物碳泵的一个组成部分，该泵将有机碳物理输送到中生层。间歇性深层混合还会破坏夏季的热分层，从而改变可用于浮游植物生长的光场和营养物浓度。再定殖后，浮游植物在混合层以下的存活和生长取决于细胞对环境变化的响应能力，细胞可以利用多种光适应过程的速度有多快。为了将夏季突发性深层混合事件的相对时间尺度与浮游植物光适应过程的时间尺度进行比较，我们首先分析了自主漂浮数据，以调查北大西洋西部深层混合事件的频率和强度。下一个，我们在实验室中模拟了持续的深度混合事件，并测量了从光收集到模型硅藻和绿藻生长的适应过程的速率。在这两种藻类中，叶绿素（Chl）的增加都与生长相关，但是绿藻的生长在大约一天的时间里落后于硅藻。在浮游剖面中，Chl和浮游植物的碳显着增加（在突发性深度混合事件之后，在混合层下方检测到了C _phyto）。这些事件在混合层之下带来了以前无法识别的新生产来源，可以显着增加可用于出口到深海的碳量。