Anthropogenic perturbations and climate change are severely threatening habitats of the global ocean, especially in the Arctic region, which is affected faster than any other ecosystem. Despite its importance and prevailing threats, knowledge on changes in its micro- and nanoplanktonic diversity is still highly limited. Here, we look back almost two decades (May 1–26, 2002) in order to expand the limited but necessary baseline for comparative field observations. Using light microscopy, a total of 196 species (taxa) were observed in 46 stations across 9 transects in the Greenland Sea. Although the number of observed species per sample ranged from 12 to 68, the diversity as effective species numbers (based on Shannon index) varied from 1.0 to 8.8, leaving about 88% as rare species, which is an important factor for the resilience of an ecosystem. Interestingly, the station with the overall highest species number had among the lowest effective species numbers. During the field survey, both number of rare species and species diversity increased with decreasing latitude. In the southern part of the examined region, we observed indications of an under-ice bloom with a chlorophyll a value of 9.9 μg l⁻¹ together with a nitrate concentration < 0.1 μM. Further, we recorded non-native species including the Pacific diatom Neodenticula seminae and the fish-kill associated diatom Leptocylindrus minimus. Our comprehensive dataset of micro- and nanoplanktonic diversity can be used for comparisons with more recent observations and continuous monitoring of this vulnerable environment—to learn from the past when looking towards the future.

人为扰动和气候变化正在严重威胁全球海洋的栖息地，尤其是在北极地区，其受到的影响比任何其他生态系统都要快。尽管其重要性和普遍存在的威胁，关于其微型和纳米浮游生物多样性变化的知识仍然非常有限。在这里，我们回顾了近 20 年（2002 年 5 月 1 日至 26 日），以扩展用于比较实地观察的有限但必要的基线。使用光学显微镜，在格陵兰海 9 个横断面的 46 个站点共观察到 196 个物种（分类群）。虽然每个样本观察到的物种数量从 12 到 68 不等，但作为有效物种数量（基于香农指数）的多样性从 1.0 到 8.8 不等，其中约 88% 为稀有物种，这是影响一个物种恢复力的重要因素生态系统。有趣的是，总物种数最高的站点的有效物种数最低。在实地调查中，稀有物种的数量和物种多样性都随着纬度的降低而增加。在检查区域的南部，我们观察到了带有叶绿素的冰下绽放的迹象9.9 μg l ^-1的值以及< 0.1 μM 的硝酸盐浓度。此外，我们还记录了非本地物种，包括太平洋硅藻Neodenticula Seminae和与鱼杀相关的硅藻Leptocylindrus minimus。我们的微型和纳米浮游生物多样性综合数据集可用于与最近的观察结果进行比较，并对这种脆弱环境进行持续监测——在展望未来时从过去学习。