Global warming affects marine ecosystems by changing environmental conditions, ecosystem structure, and ecosystem functioning. In parts of the Arctic, increased sea temperature and decreased sea ice have led to a poleward expansion of boreal species and increased their interactions with native Arctic species. To investigate and quantify the changing interactions in an Arctic marine food web under new environmental conditions, we studied the interactions between key prey fish species in the seasonally ice-covered parts of the Barents Sea: adult polar cod (Boreogadus saida) and capelin (Mallotus villosus) and one of the major predators in the system: Atlantic cod (Gadus morhua). For this, we compared the predictive performance of threshold models predicting the abundance of adult polar cod as a function of Atlantic cod. Each model was associated with a hypothesis describing prey-predator interactions in different environmental conditions defined by threshold values of summer sea-ice or capelin stock biomass. The best predictive model showed that the predation effect of Atlantic cod on polar cod was strongest in years of low summer sea ice cover and low capelin stock biomass. Our results exemplified that Arctic species such as polar cod may experience increased predation pressure under climate change from boreal species such as Atlantic cod. These effects depend, however, not only on changes in abiotic drivers of species distributions, but also on food-web interactions involving mid-trophic level species such as capelin.

中文翻译：

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气候变化下北极食物网中猎物-捕食者相互作用的变化


全球变暖通过改变环境条件、生态系统结构和生态系统功能来影响海洋生态系统。在北极部分地区，海水温度升高和海冰减少导致北方物种向极地扩张，并增加了它们与北极本地物种的互动。为了研究和量化新环境条件下北极海洋食物网中不断变化的相互作用，我们研究了巴伦支海季节性冰雪覆盖部分的主要猎物鱼类物种之间的相互作用：成年极地鳕鱼 （Boreogadus saida） 和毛鳞鱼 （Mallotus villosus） 以及系统中的主要捕食者之一：大西洋鳕鱼 （Gadus morhua）。为此，我们比较了预测成年极地鳕鱼丰度的阈值模型的预测性能作为大西洋鳕鱼的函数。每个模型都与一个假设相关联，该假设描述了不同环境条件下猎物与捕食者的相互作用，该假设由夏季海冰或毛鳞鱼种群生物量的阈值定义。最佳预测模型显示，大西洋鳕鱼对极地鳕鱼的捕食作用在夏季海冰覆盖率低和毛鳞鱼种群生物量低的年份最强。我们的结果表明，在气候变化下，北极物种（如极地鳕鱼）可能会承受来自大西洋鳕鱼等北方物种的更大捕食压力。然而，这些影响不仅取决于物种分布的非生物驱动因素的变化，还取决于涉及毛鳞鱼等中营养级物种的食物网相互作用。