Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis was conducted on modern and archaeological polar bear bone collagen from the Canadian Arctic Archipelago to investigate potential changes in polar bear foraging ecology over four-millennia. Polar bear δ¹³C values showed a significant decline in the modern samples relative to all archaeological time-bins, indicating a disruption in the sources of production that support the food web, occurring after the Industrial Revolution. The trophic structure, indicated through δ¹⁵N, remained unaltered throughout all time periods. The lower δ¹³C observed in the modern samples indicates a change in the relative importance of pelagic (supported by open-water phytoplankton) over sympagic (supported by sea ice-associated algae) primary production. The consistency in polar bear δ¹³C through the late Holocene includes climatic shifts such as the Medieval Warm Period (MWP, A.D. 950–1250) and the early stages of the Little Ice Age (LIA, A.D. 1300–1850). These findings suggest that polar bears inhabit a food web that is more pelagic and less sympagic today than it was through the Late Holocene. We suggest that modern, anthropogenic warming has already affected food web structure in the Canadian Arctic Archipelago when modern data are contextualized with a deep time perspective.

对加拿大北极群岛的现代和考古北极熊骨胶原进行稳定碳 ( δ ¹³ C) 和氮 ( δ ^{15 N) 同位素分析，以研究四千年来北极熊觅食生态的潜在变化。}北极熊δ ¹³ C 值显示，相对于所有考古时间段，现代样本中的 δ 13 C 值显着下降，这表明支持食物网的生产来源在工业革命后发生了破坏。通过δ ^{15 N}表示的营养结构在所有时间段内都保持不变。较低^的δ13在现代样本中观察到的 C 表明，中上层（由开放水域浮游植物支持）相对于共生（由海冰相关藻类支持）初级生产的相对重要性发生了变化。北极熊δ ¹³ C 到全新世晚期的一致性包括气候变化，例如中世纪温暖期（MWP，公元 950-1250 年）和小冰期早期（LIA，公元 1300-1850 年）。这些发现表明，与全新世晚期相比，如今北极熊所栖息的食物网更加远洋，但交配性较差。我们认为，当现代数据与深层时间视角结合起来时，现代人为变暖已经影响了加拿大北极群岛的食物网结构。