Remineralization of organic matter at the seafloor is an important ecosystem function, as it drives carbon and nutrient cycling, supplying nutrients for photosynthetic production, but also controls carbon burial within the sediment. In the Arctic Ocean, changes in primary production due to rapid sea-ice decline and thinning affect the export of organic matter to the seafloor and thus, benthic ecosystem functioning. Due to the remoteness and difficult accessibility of the Arctic Ocean, we still lack baseline knowledge about patterns of benthic remineralization rates and their drivers in both shelf and deep-sea sediments. Particularly comparative studies across regions are scarce. Here, we address this knowledge gap by contrasting benthic diffusive and total oxygen uptake rates (DOU and TOU), both established proxies of the benthic remineralization function, between shelf and deep-sea habitats of the Barents Sea and the central Arctic Ocean, sampled during a RV Polarstern expedition in 2015. DOU and TOU were measured using ex situ porewater oxygen microprofiles and sediment core incubations, respectively. In addition, contextual parameters including organic matter availability and microbial cell numbers were determined as environmental predictors. Pan-Arctic regional comparisons were obtained by extending our analyses to previously published data from the Laptev and Beaufort Seas. Our results show that (1) benthic oxygen uptake rates and most environmental predictors varied significantly between shelf and deep-sea habitats; (2) the availability of detrital organic matter is the main driver for patterns in total as well as diffusive respiration, while bacterial abundances were highly variable and only a weak predictor of differences in TOU and DOU; (3) regional differences in oxygen uptake across shelf and deep-sea sediments were mainly related to organic matter availability and may reflect varying primary production regimes and distances to the nearest shelf. Our findings suggest that the expected decline in sea-ice cover and the subsequent increase in export of organic matter to the seafloor may particularly enhance remineralization in the deep seas of the Arctic Ocean, altering benthic ecosystem functioning in future climate scenarios.

中文翻译：

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北极大陆架和深海沉积物中底栖生态系统功能的可变性：根据底栖氧气吸收率和环境驱动因素进行评估

海底有机物的再矿化是一项重要的生态系统功能，因为它驱动碳和养分循环，为光合生产提供养分，但也控制沉积物中的碳埋藏。在北冰洋，由于海冰迅速减少和变薄导致初级生产的变化影响了有机物向海底的输出，从而影响了底栖生态系统的功能。由于北冰洋地处偏远且难以进入，我们仍然缺乏关于陆架和深海沉积物中底栖再矿化率模式及其驱动因素的基线知识。特别是跨地区的比较研究很少。在这里，我们通过对比底栖扩散和总摄氧率（DOU 和 TOU）来解决这一知识差距，在 2015 年 RV Polarstern 探险期间对巴伦支海和北冰洋中部大陆架和深海栖息地之间的底栖再矿化功能的既定代表进行了采样。 DOU 和 TOU 是使用异地孔隙水氧微观剖面和沉积物核心孵化测量的， 分别。此外，包括有机物质可用性和微生物细胞数量在内的上下文参数被确定为环境预测因子。泛北极区域比较是通过将我们的分析扩展到先前发布的来自拉普捷夫海和波弗特海的数据获得的。我们的研究结果表明：（1）海底吸氧率和大多数环境预测因子在大陆架和深海栖息地之间存在显着差异；(2) 碎屑有机质的可用性是总模式和扩散呼吸的主要驱动因素，而细菌丰度变化很大，并且只是 TOU 和 DOU 差异的弱预测因子；(3) 陆架和深海沉积物氧气吸收的区域差异主要与有机物的可用性有关，可能反映了不同的初级生产方式和到最近的陆架的距离。我们的研究结果表明，海冰覆盖的预期下降以及随后向海底出口的有机物质的增加可能会特别增强北冰洋深海的再矿化，从而改变未来气候情景中底栖生态系统的功能。(3) 陆架和深海沉积物氧气吸收的区域差异主要与有机物的可用性有关，可能反映了不同的初级生产方式和到最近的陆架的距离。我们的研究结果表明，海冰覆盖的预期下降以及随后向海底出口的有机物质的增加可能会特别增强北冰洋深海的再矿化，从而改变未来气候情景中底栖生态系统的功能。(3) 陆架和深海沉积物氧气吸收的区域差异主要与有机物的可用性有关，可能反映了不同的初级生产方式和到最近的陆架的距离。我们的研究结果表明，海冰覆盖的预期下降以及随后向海底出口的有机物质的增加可能会特别增强北冰洋深海的再矿化，从而改变未来气候情景中底栖生态系统的功能。