Phytoplankton biomass in Monterey Bay, California is typically dominated by diatoms, but it shifted to dinoflagellates twice in the past 18 years (2004–2007, 2017–2018), which was associated with increased harmful algal blooms. Located within the central California Current System (CCS), Monterey Bay is strongly influenced by cycles of upwelling‐favorable winds and their relaxation or reversal. Both dinoflagellate‐dominated periods were linked to a negative North Pacific Gyre Oscillation (NPGO) and increased river discharge, but each had a different relationship with upwelling. To examine the connection between large‐scale and local forcings underlying floristic shifts in the phytoplankton assemblage, an Imaging FlowCytobot (IFCB) was deployed within the Monterey Bay upwelling shadow for a full year. A machine learning classifier differentiating IFCB images of the phytoplankton assemblage was developed. Despite anomalously strong upwelling in 2018, dinoflagellates comprised 57% of the annual phytoplankton‐specific biomass. During upwelling, dinoflagellates appear to have accumulated at convergent fronts, while during relaxation these frontal populations were transported to the nearshore where they seeded local blooms. Frequent upwelling‐relaxation cycles and local wind anomalies generated an unusually retentive circulation pattern in the upwelling shadow, producing a warm and stratified bloom incubator. Thus, local features and forcings (upwelling shadow, winds, river discharge) modified the effects of regional‐ and basin‐scale oceanographic variability (regional upwelling, NPGO), altering local phytoplankton patterns. As North Pacific decadal variability and CCS upwelling intensity increase under climate warming, dinoflagellates may become more common in some CCS regions, due to the enhancement or mitigation of large‐scale trends by local forcings.

中文翻译：

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蒙特利湾“鞭毛虫年龄”的回归：使用自动成像流式细胞仪和长期时间序列分析检查了鞭毛虫主导地位的驱动因素

加利福尼亚州蒙特雷湾的浮游植物生物量通常以硅藻为主，但在过去的18年中（2004-2007、2017-2018），它两次移入藻鞭藻，这与有害藻类大量繁殖有关。蒙特利湾位于加利福尼亚中央水流系统（CCS）内，受到上升气流和逆风或逆风的强烈影响。两个鞭毛藻主导的时期都与北太平洋回旋涛动（NPGO）负相关并且河流流量增加，但是每个时期与上升流的关系不同。为了检查浮游植物组合中植物区系转移背后的大规模强迫与局部强迫之间的联系，在蒙特利湾上升流阴影中部署了一个影像流机器人（IFCB）整整一年。开发了一种区分浮游植物组合的IFCB图像的机器学习分类器。尽管2018年异常强烈上升，但鞭毛藻仍占浮游植物特异性生物量的57％。在上升流期间，藻鞭毛似乎聚集在会聚的锋线上，而在放松过程中，这些锋芒种群被运送到近岸，在那里他们播种了当地的花朵。频繁的上升流松弛周期和局部风异常在上升流阴影中产生了异常的保持性循环模式，从而产生了温暖且分层的水华孵化器。因此，局部特征和强迫（上升阴影，风向，河流流量）改变了区域和流域尺度海洋变化的影响（区域上升流，NPGO），改变了局部浮游植物的格局。