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Impact of Glaciers on Trophic Dynamics and Polyunsaturated Fat Accumulation in Southern Greenland Fjord Ecosystems
Global Change Biology ( IF 10.8 ) Pub Date : 2025-01-27 , DOI: 10.1111/gcb.70044
Grégoire Saboret, Coralie Moccetti, Leonard I. Wassenaar, Blake Matthews, Norberto Jr. Aquino, David J. Janssen, Jakob Brodersen, Carsten J. Schubert

The primary production of fjords across the Arctic and Subarctic is undergoing significant transformations due to the climatically driven retreat of glaciers and ice sheets. However, the implications of these changes for upper trophic levels remain largely unknown. In this study, we employ both bulk and compound‐specific stable isotope analyses to investigate how shifts at the base of fjord food webs impact the carbon and energy sources of consumers. Focusing on two rapidly changing fjords in Southern Greenland, we used the migratory Arctic char as an indicator species, sampling populations along environmental gradients within the fjords, building upon the assumption that char populations feed primarily close to their natal stream, thereby integrating a dietary gradient. Our analysis of bulk stable isotopes in Arctic char tissue confirmed this premise, revealing a consistent change in resource use from the outer to the inner fjord, which nonetheless served as preferred feeding grounds. Essential amino acid analysis further indicated shifts in carbon and nitrogen sources, consistent with changes in nutrient use near glacier inputs characterized by low turbidity and high iron levels. Notably, these changes in the source of primary production were associated with shifts in trophic positions and the transfer of polyunsaturated fatty acids, with Arctic char in glacier‐influenced inner fjords feeding at lower trophic level (size‐corrected) and accumulating higher levels of high‐quality docosahexaenoic acid (DHA). These findings highlight the usefulness of new analytical tools in revealing that glacial retreat can substantially alter food web dynamics, enhancing both carbon flow and the nutritional quality of fish in fjord ecosystems. The two Southern Greenland fjords studied could represent the future of other fjords, where retreating glaciers become land‐terminating and glacial inputs decrease. Our study underscores the critical role of glacier dynamics in affecting high‐level consumers, such as salmonids, with implications for fjords globally.

中文翻译:


冰川对格陵兰南部峡湾生态系统营养动力学和多不饱和脂肪积累的影响



由于气候驱动的冰川和冰盖退缩,北极和亚北极峡湾的初级生产正在发生重大变化。然而,这些变化对上营养级的影响在很大程度上仍然未知。在这项研究中,我们采用块状和化合物特异性稳定同位素分析来研究峡湾食物网底部的变化如何影响消费者的碳和能源。我们专注于格陵兰岛南部两个快速变化的峡湾,使用洄游的北极红点鲑作为指示物种,沿着峡湾内的环境梯度对种群进行采样,建立在红点鲑种群主要在其出生溪附近觅食的假设之上,从而整合了饮食梯度。我们对北极红点鲑组织中大量稳定同位素的分析证实了这一前提,揭示了从外部峡湾到内部峡湾的资源利用持续变化,尽管如此,内峡湾仍然是首选的觅食地。必需氨基酸分析进一步表明碳和氮来源的变化,这与冰川输入附近营养物质利用的变化一致,其特点是低浊度和高铁含量。值得注意的是,初级生产来源的这些变化与营养位置的变化和多不饱和脂肪酸的转移有关,受冰川影响的内峡湾中的北极红点鲑在较低的营养级(大小校正)觅食,并积累了更高水平的高质量二十二碳六烯酸 (DHA)。这些发现强调了新分析工具的有用性,它揭示了冰川退缩可以显着改变食物网动态,提高峡湾生态系统中碳流动和鱼类的营养质量。 所研究的两个南格陵兰峡湾可能代表了其他峡湾的未来,在这些峡湾中,消退的冰川成为陆地的终点,冰川输入减少。我们的研究强调了冰川动力学在影响鲑鱼等高级消费者方面的关键作用,这对全球峡湾的影响。
更新日期:2025-01-27
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