To understand the effect of an unusually early sea-ice retreat in the northern Bering Sea in the spring of 2018 on the marine ecosystem of the northern Bering Sea, we compared at-sea observations of seabird density and acoustic observations of prey (fish and zooplankton) biomass during shipboard surveys around St. Lawrence Island in the summers of 2017 and 2018. Densities of foraging seabirds in 2018 (piscivorous divers: 4.7 birds km⁻², planktivorous divers: 5.1, shearwaters: 0.7, surface feeders: 6.6) were lower than those in 2017 (piscivorous divers: 14.7 birds km⁻², planktivorous divers: 10.3, shearwaters: 11.9, surface feeders:11.9). Acoustically-determined prey biomass in 2018 (fish: 6.4 m²nmi⁻², zooplankton: 2.3) was also lower than in 2017 (fish: 18.4 m²nmi⁻², zooplankton: 5.5). Similarly, biomass of macrozooplankton (amphipods, euphausiids, Neocalanus spp. and Calanus marshallae) sampled using bongo nets was smaller in 2018. At scales of 5–30 km, correlations between the seabird density and prey biomass were weaker (−0.2–0.3 of Pearson's r) in 2018 than those in 2017 (0.4–0.9) for all seabirds except planktivorous divers. We suggest that the lack of sea ice, and the resulting lack of ice-edge phytoplankton blooms, may weaken trophic linkages by causing a low biomass of secondary consumers and hence a reduced density of seabirds.

为了了解2018年春季在白令海北部异常早期的海冰退缩对白令海北部的海洋生态系统的影响，我们比较了海鸟密度和猎物（鱼类和浮游动物）的海上观测结果）围绕圣劳伦斯岛船上调查中的觅食海鸟2017和2018中密度2018夏天期间生物质（食鱼潜水员：4.7鸟类公里^-2，planktivorous潜水员：5.1，鹱：0.7，表面馈线：6.6）均较低比2017年的增速有所提高（食肉性潜水员：14.7鸟km ^-2，板食性潜水员：10.3，剪切水：11.9，地面饲养者：11.9）。根据声音确定的2018年猎物生物量（鱼：6.4 m ² nmi ^-2，浮游动物：2.3）也低于2017年（鱼类：18.4 m ² nmi ^-2，浮游动物：5.5）。类似地，大型浮游动物的生物量（足目，磷虾，Neocalanus属和哲marshallae使用邦戈网取样）在2018年较小在5-30公里秤，海鸟密度和猎物生物量之间的相关性较弱（-0.2-0.3的除浮游动物外，所有海鸟的Pearson's r）在2018年均高于2017年（0.4-0.9）。我们建议缺乏海冰，以及由此导致的缺乏冰缘浮游植物的开花，可能会导致次生消费者生物量降低，从而降低海鸟的密度，从而削弱营养联系。