Food-web structure determines the cycling pathways and fate of new production in marine ecosystems. Herbivorous zooplankton populations are usually seasonally coupled with pelagic primary producers. Synchrony of phytoplankton blooms with reproduction, recruitment and seasonal ascent of their main grazers ensures efficient transfer of organic carbon to higher trophic levels, including commercially harvested species, especially in high-latitude systems. Changes in light, nutrient, and sea-ice dynamics due to accelerating climate change in the Arctic, however, create large uncertainties in how these systems will function in the future. To address such knowledge gaps, we surveyed the pelagic ecosystem of the Barents Sea Polar Front in May of two consecutive years (2021 and 2022) to investigate the pelagic food-web from primary producers to planktivorous fish. In both years we observed unprecedentedly high phytoplankton chlorophyll a values in open as well as ice-covered waters, much of which was invisible to satellite remote sensing. We also measured very low densities of grazing zooplankton across a wide area and extending for at least one month. This extreme mismatch resulted in low feeding by capelin, and further suggests a high potential for vertical export of carbon to the benthos rather than efficient assimilation into the pelagic food web. As the Arctic continues to warm and is characterized by thinner and more mobile sea ice, we may expect higher variability in phytoplankton bloom phenology and more frequent mismatches with grazer life-histories. This could have significant impacts on ecosystem functioning by re-directing the flow of energy through the system towards seafloor rather than to the production of commercially valuable pelagic marine resources.

中文翻译：

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北极春季开花期间浮游植物和食草动物之间的极端不匹配及其对中上层食物网的影响


食物网结构决定了海洋生态系统中新生产的循环途径和命运。食草性浮游动物种群通常与中上层初级生产者季节性结合。浮游植物大量繁殖与其主要食草动物的繁殖、补充和季节性上升同步，确保了有机碳有效地转移到更高的营养级，包括商业收获的物种，特别是在高纬度系统中。然而，由于北极气候变化的加速，光、营养和海冰动态的变化给这些系统在未来如何运作带来了巨大的不确定性。为了解决此类知识差距，我们连续两年（2021 年和 2022 年）的 5 月调查了巴伦支海极锋的中上层生态系统，以调查从初级生产者到浮游食性鱼类的中上层食物网。在这两年中，我们在开阔水域和冰雪覆盖的水域观察到了前所未有的高浮游植物叶绿素 a 值，其中大部分是卫星遥感看不到的。我们还测量了大面积放牧浮游动物的非常低密度，并且至少持续了一个月。这种极端的不匹配导致毛鳞鱼的摄食量低，并进一步表明碳垂直输出到底栖生物的可能性很高，而不是有效地同化到中上层食物网中。随着北极继续变暖，海冰更薄、流动性更强，我们预计浮游植物大量繁殖物候的变化会更高，与食草动物生活史的不匹配也会更频繁。这可能会对生态系统的功能产生重大影响，因为它将通过系统将能量流重新引导到海底，而不是生产具有商业价值的中上层海洋资源。