Recent dramatic reductions of winter sea ice in the northern Bering Sea have raised the possibility that a rapid ecological transformation is underway. It has been hypothesized that with sufficient sea ice loss the cold pool thermal barrier separating the northern and southern Bering Sea would be breached, potentially benefiting piscivorous seabirds with an influx of abundant forage fish, but maybe causing food limitations for planktivorous seabirds that rely on cold-water associated species of zooplankton. During 2016–2019, we examined responses of the seabird community breeding on St. Lawrence Island to variable winter sea ice extent (low in 2018–2019). The seabird community includes piscivorous black-legged kittiwakes, thick-billed and common murres, and planktivorous crested and least auklets. We used a combination of stable isotope analysis and nutritional stress status analyses to examine if the region's ecosystem has shifted to a pelagic prey base, and whether either foraging guild benefitted from such a shift. To interpret bird responses, we used stable isotope analyses of prey and trawl survey-derived abundance of forage size fish. Stable isotope values in blood tissues revealed no change in the prey base as reflected in the isotopic space used by the seabird community across the four study years. Sea-ice loss was, however, associated with increased nutritional stress in all seabird species and diverging foraging niches within guilds. Benthic forage-sized fish remained a key food source, with their abundance stable since 2010, and benthic-foraging thick-billed murres experienced relatively low nutritional stress across the study period. A significant increase in common murre nutritional stress levels between 2016 and 2017, and a shift in their isotopic niche indicative of higher reliance on benthic prey coincided with a decline in the abundance of pelagic forage fish in the region. Surface-foraging black-legged kittiwakes experienced steady increases in nutritional stress as the abundance of pelagic forage fish declined. The spring sea-ice loss was detrimental to planktivorous least and crested auklets that rely on zooplankton advected from the Bering Sea basin. During the study period both auklets have experienced severe nutritional stress (2018) and colony-wide reproductive failures (2018 and 2019). In conclusion, we found that increasingly warm conditions during 2016–2019 have challenged the adaptive ability of seabirds relying on pelagic fish and zooplankton advected into the region each summer, but have not yet resulted in a reorganization of the northern Bering Sea's benthic-dominated ecosystem.

白令海北部冬季海冰最近急剧减少，这增加了进行快速生态转型的可能性。据推测，如果海冰大量流失，将打破白令海北部和南部分隔的冷水池热障，可能使大量食草鱼大量涌入食鱼海鸟，但可能会给依赖冷食的浮游海鸟造成食物限制浮游动物的水相关物种。在2016–2019年期间，我们研究了圣劳伦斯岛海鸟群落繁殖对冬季海冰变化的响应（2018–2019年较低）。海鸟群落包括食肉性黑脚Kittiwakes，粗嘴和常见的泥潭，以及浮游性的凤头和最少的红鳍金枪鱼。我们结合使用了稳定同位素分析和营养胁迫状态分析，以检查该地区的生态系统是否已转变为中上层捕食基地，以及觅食行会是否从这种转变中受益。为了解释鸟类的反应，我们使用了稳定的猎物和拖网调查得出的饲草大小鱼的丰度同位素分析。在这四个研究年中，海鸟群落所使用的同位素空间反映出血液组织中稳定的同位素值未显示猎物碱的变化。然而，海冰的流失与所有海鸟物种的营养压力增加以及行会中觅食壁ni的分散有关。自2010年以来，底栖饲草大小的鱼类仍然是主要的食物来源，其丰度稳定，在整个研究期间，底栖觅食的大嘴黑鲈的营养压力相对较低。在2016年至2017年之间，普通鼠类营养应激水平显着增加，其同位​​素生态位的变化表明对底栖动物的依赖性更高，与此同时该区域中上层饲料鱼的数量减少。随着中上性饲草鱼的丰度下降，表面觅食的黑脚Kittiwakes的营养压力持续增加。春季海冰的损失对浮游生物的危害最小，而依赖于白令海盆地平流浮游动物的凤头小a鱼则不利。在研究期间，两个秋葵都经历了严重的营养压力（2018）和整个菌落的生殖衰竭（2018和2019）。结论，