As ocean temperatures rise, sub-Arctic capelin (Mallotus villosus) and sand lance (Ammodytes spp.) have become increasingly abundant in regions of the eastern Canadian Arctic. These fish have a similar trophic role to the keystone polar cod (Boreogadus saida), potentially competing for food resources when co-occurring. To evaluate this, we calculated feeding niche breadth and overlap based on fatty acids and δ15N- and δ13C-derived trophic position and carbon source, among sub-Arctic fish and 10 Arctic fish and invertebrates within low, mid, and high latitudes of the Canadian Arctic. Diverse feeding strategies including benthic Myoxocephalus sp., anadromous and pelagic fish, led to limited feeding niche overlap among species (13% average, range 0–96%). Feeding niche overlap between capelin and sand lance from the low Arctic was generally high (36–93%); while fatty acid niches of these fish overlapped 0–21% with polar cod in the mid and high Arctic, and their isotopic niches overlapped up to 96%. Capelin and sand lance showed 3–8 times broader feeding niches than polar cod. Regarding regional variation, polar cod had similar niche breadth between regions and highly overlapping fatty acid niches. Niche variation for Myoxocephalus sp. and Gammarus spp. between low and high Arctic was likely associated with more diverse sources of primary production in the shallower, more brackish low Arctic. Although regional variation in food availability play an important role defining feeding niches, broader niches and isotopic niche overlap with polar cod indicated a potential ecological advantage for capelin and sand lance over polar cod under climate change.

中文翻译：

---

毛鳞鱼和沙枪的广泛觅食生态位可能与加拿大东部北极地区的极地鳕鱼和其他本地鱼类的觅食生态位重叠

随着海洋温度的升高，亚北极毛鳞鱼（Mallotus villosus）和沙枪鱼（Ammodytes spp.）在加拿大东部北极地区变得越来越丰富。这些鱼与基石极地鳕鱼 (Boreogadus saida) 具有相似的营养作用，同时出现时可能会争夺食物资源。为了评估这一点，我们根据脂肪酸和 δ15N 和 δ13C 衍生的营养位置和碳源，计算了加拿大低、中和高纬度地区亚北极鱼类和 10 种北极鱼类和无脊椎动物的饲养生态位宽度和重叠。北极。包括底栖粘头鱼、溯河鱼类和中上层鱼类在内的多样化饲养策略导致物种之间的饲养生态位重叠有限（平均 13%，范围 0-96%）。来自低北极的毛鳞鱼和沙枪之间的觅食生态位重叠普遍较高（36-93%）；而这些鱼类的脂肪酸生态位与北极中高地区的极地鳕鱼重叠 0-21%，它们的同位素生态位重叠高达 96%。毛鳞鱼和沙枪鱼的觅食生态位是极地鳕鱼的 3-8 倍。关于区域变异，极地鳕鱼在区域之间具有相似的生态位宽度和高度重叠的脂肪酸生态位。Myoxocephalus sp. 的生态位变异。和 Gammarus spp。低北极和高北极之间的差异可能与更浅、更咸的低北极初级生产来源更加多样化有关。尽管食物供应的区域差异在定义喂养利基方面发挥着重要作用，