AIM: Phytoplankton form the basis of the marine food web and are responsible for approximately 50% of the world's photosynthesis. Changes to their ecology are, therefore, important: here, we examined seasonal patterns in ocean phytoplankton abundance for 45 taxa over 59 years collected from circa 410,000 km of line‐transect sampling at temperate latitudes. LOCATION: The North Sea. METHODS: For our analysis we used plankton abundance data from the Continuous Plankton Recorder (CPR) survey, sea surface temperature measurements from the Hadley Centre, UK Meteorological Office and wind speed data from the International Comprehensive Ocean–Atmosphere Data Set, NOAA. RESULTS: We found large differences in changes in the timing of peak abundance between the major phytoplankton groups. Late‐summer blooming dinoflagellates (n = 10 taxa) tended to show a large seasonal advancement, the timing of peak abundance for dinoflagellates as group advancing 39 days over these six decades. By contrast diatoms (n = 35) did not show any change as a group in their timing of peak abundance over the time series. Granger causality testing suggested a major driver of these phenological changes has been ocean warming in general but more specifically the rate of spring temperature rise as the most important factor. We also found differences in the timing of peak abundance of harmful algal bloom taxa, with some showing peak abundance earlier while others have moved later. MAIN CONCLUSIONS: There has been a fundamental transformation of the classic seasonal progression from blooms of diatoms to dinoflagellates, which lies at the heart of temperate marine food chains, as the classic bimodal diatom and dinoflagellate seasonal peaks are eroded to a more continuous, single, longer‐lasting phytoplankton peak. This phenological shuffling within and between major taxonomic groups is likely to have profound implications for the transfer of energy to higher trophic levels.

中文翻译：

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过去 60 年主要海洋浮游植物群的物候改组

目标：浮游植物是海洋食物网的基础，约占世界光合作用的 50%。因此，它们的生态变化很重要：在这里，我们检查了 59 年来从温带纬度约 410,000 公里的线样断面采样中收集的 45 个分类群的海洋浮游植物丰度的季节性模式。地点：北海。方法：在我们的分析中，我们使用了来自连续浮游生物记录仪 (CPR) 调查的浮游生物丰度数据、来自英国气象局哈德利中心的海面温度测量值以及来自 NOAA 国际综合海洋-大气数据集的风速数据。结果：我们发现主要浮游植物群之间峰值丰度的时间变化存在很大差异。夏末盛开的甲藻（n = 10 个分类群）往往表现出较大的季节性提前，甲藻的峰值丰度时间在这六个十年中作为群体提前了 39 天。相比之下，硅藻 (n = 35) 作为一个群体在时间序列中的峰值丰度时间没有任何变化。格兰杰因果关系测试表明，这些物候变化的主要驱动因素是总体上的海洋变暖，但更具体地说，春季温度上升的速度是最重要的因素。我们还发现有害藻华类群的峰值丰度时间存在差异，一些峰值丰度较早，而另一些则晚一些。主要结论：从硅藻的大量繁殖到甲藻的经典季节性进程发生了根本性的转变，它位于温带海洋食物链的核心，因为经典的双峰硅藻和甲藻季节性高峰被侵蚀为更连续、单一、更持久的浮游植物高峰。主要分类群内部和之间的这种物候改组可能对能量转移到更高的营养水平产生深远的影响。