We address here the specific timing and amplitude of sea-surface conditions and productivity changes off SW Greenland, northern Labrador Sea, in response to the high deglacial meltwater rates, the Early Holocene maximum insolation and Neoglacial cooling. Dinocyst assemblages from sediment cores collected off Nuuk were used to set up quantitative records of sea ice cover, seasonal sea-surface temperature (SST), salinity (SSS), and primary productivity, with a centennial to millennial scale resolution. Until ~10 ka BP, ice-proximal conditions are suggested by the quasi-exclusive dominance of heterotrophic taxa and low dinocyst concentrations. At about 10 ka BP, an increase in species diversity and abundance of phototrophic taxa marks the onset of interglacial conditions at a regional scale, with summer SST reaching up to 10 °C between 8 and 5 ka BP, thus in phase with the Holocene Thermal Maximum as recorded in the southern Greenlandic areas/northern Labrador Sea. During this interval, low SSS but high productivity prevailed in response to high meltwater discharge and nutrient inputs from the Greenland Ice Sheet. After ~5 ka BP, a decrease in phototrophic taxa marks a two-step cooling of surface waters. The first started at ~5 ka BP, and the second at ~3 ka BP, with a shift toward colder conditions and higher SSS suggesting reduced meltwater discharge during the Neoglacial. This second step coincides with the disappearance of the Saqqaq culture. The gap in human occupation in west Greenland, between the Dorset and the Norse settlements from 2000 to 1000 years BP, might be linked to high amplitude and high frequency variability of ocean and climate conditions.

中文翻译：

---

全新世期间格陵兰岛西南海域的日照与融水对生产力和海面条件的控制

我们在这里讨论了海面条件和生产力变化的具体时间和幅度，以应对拉布拉多海北部格陵兰岛西南部的高冰消融水率、早全新世最大日照和新冰期冷却。从努克附近收集的沉积岩芯中的 Dinocyst 组合被用来建立海冰覆盖、季节性海面温度 (SST)、盐度 (SSS) 和初级生产力的定量记录，具有百年到千年的分辨率。直到大约 10 ka BP，异养类群的准排他性优势和低双囊藻浓度表明了近冰条件。在大约 10 ka BP，物种多样性和光养类群丰度的增加标志着区域尺度间冰期条件的开始，夏季海温在 8 和 5 ka BP 之间达到 10 °C，因此，与格陵兰南部地区/拉布拉多海北部记录的全新世最高热期处于同一阶段。在此期间，由于高融水排放和格陵兰冰盖的养分输入，SSS 较低但生产力较高。在~5 ka BP 之后，光养类群的减少标志着地表水的两步冷却。第一个开始于~5 ka BP，第二个在~3 ka BP，向更冷的条件和更高的SSS转变，表明新冰期期间融水排放减少。第二步恰逢萨卡克文化的消失。从 2000 年到 1000 年 BP，西格陵兰岛多塞特人和北欧人定居点之间的人类占领差距可能与海洋和气候条件的高振幅和高频率变化有关。