The impacts of climate change on north Atlantic nutrient chemistry remain poorly understood, as there exist a multitude of rapidly changing biological and physical drivers of nutrient conditions throughout the region. Here, we present nitrogen isotope measurements derived from a six‐hundred‐year‐old crustose coralline alga (δ¹⁵N_algal) to elucidate historical and contemporary trends in nitrate utilization and circulation patterns along the Labrador Shelf. Prior to the early 1900s, we argue that intervals during which utilization approached completion were controlled by reduced nitrate advection linked to an increased proportion of nitrate‐poor polar waters and subdued Atlantic influence, as expected from concurrent negative modes of the Atlantic multidecadal oscillation. While nitrate conditions should have recovered in recent years, our record suggests that high utilization persisted since ∼1870, which we also attribute to reduced Atlantic advection, likely associated with the twentieth‐century anthropogenic weakening of the Atlantic meridional overturning circulation. These results highlight the role of ongoing climate‐induced circulation changes in modulating nutrient distributions throughout the subpolar north Atlantic, which may have implications for other environmental phenomena such as fisheries and oceanic carbon storage.

中文翻译：

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拉布拉多大陆架上的气候调节养分状况：六百年的rust壳珊瑚藻中氮同位素的证据

人们对气候变化对北大西洋营养化学的影响知之甚少，因为在整个地区，营养条件的生物和物理驱动因素迅速变化。在这里，从六百年历史的壳状珊瑚藻（δ派生我们存在的氮同位素测量¹⁵ ñ_藻），以阐明拉布拉多大陆架沿线硝酸盐利用和循环模式的历史和当代趋势。在1900年代初之前，我们认为，利用接近完成的时间间隔受硝酸盐平流减少的控制，这与硝酸盐稀少的极性水比例的增加和大西洋的影响减弱有关，正如大西洋多年代际振荡的同时出现的负模所预期的那样。尽管近年来硝酸盐的状况应该有所恢复，但我们的记录表明，自1870年以来，高利用率一直持续存在，这也归因于大西洋对流的减少，这可能与20世纪人为导致大西洋经向翻转环流减弱有关。