Understanding species phenology and temporal co‐occurrence across trophic levels is essential to assess anthropogenic impacts on ecological interactions. We analyzed 15 yr of monitoring data to identify trends and drivers of timing and magnitude of bloom‐forming phytoplankton and diverse zooplankton taxa in the central Baltic Sea. We show that the timings of phytoplankton blooms advance, whereas crustacean zooplankton seasonal timings remain constant. This increasing offset with the spring bloom is linked to the decline of Pseudocalanus, a key copepod sustaining pelagic fish production. The majority of copepod and cladoceran taxa, however, are co‐occurring with summer blooms. We also find new developing fall blooms, fueling secondary production later in the season. Our study highlights that response to climate change differs within and between functional groups, stressing the importance of investigating plankton phenologies over the entire annual cycle in pelagic systems.

中文翻译：

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浮游生物在年度周期中大量繁殖，形成气候变化下的营养相互作用

了解物种物候和跨营养级别的时间共现对于评估人为对生态相互作用的影响至关重要。我们分析了 15 年的监测数据，以确定波罗的海中部浮游植物和不同浮游动物类群的水华形成时间和规模的趋势和驱动因素。我们发现浮游植物繁殖的时间提前，而甲壳类浮游动物的季节性时间保持不变。这种与春季花期的抵消增加与花期的减少有关。拟竹属，维持远洋鱼类生产的关键桡足类动物。然而，大多数桡足类和枝角类群与夏季开花同时发生。我们还发现新的秋季开花，促进了该季节后期的二次生产。我们的研究强调，功能组内部和功能组之间对气候变化的反应有所不同，强调了研究浮游生物物候在中上层系统整个年度周期中的重要性。