Frozen tundra soils hold one of the Earth's largest pools of organic carbon. Climate warming and the associated permafrost thaw release a large fraction of this carbon into circumpolar lakes, inducing extreme browning that fuels the heterotrophic microbial food web. How this permafrost carbon affects organisms higher in the food chain remains unknown. Using dissolved organic matter properties, total phosphorus, chlorophyll a, fatty acids, and stable isotopes, we investigated the influence of thawing permafrost on primary producers and primary consumers of the planktonic food web. We sampled four subarctic thaw ponds that were affected by permafrost carbon and another four ponds that were not. Our results highlight the stimulating influence of eroding and degrading ice‐rich permafrost on nutrients and planktonic algae. Relative to the non‐thaw ponds, the permafrost thaw‐influenced freshwaters had higher total phosphorus concentrations (14.8 vs. 70.4 µg/L, respectively). This in turn led to a higher chlorophyll a (2.7 vs. 45.2 µg/L) and seston omega‐3 fatty acid concentrations (7.3 vs. 53.5 µg/L) despite significantly reduced light for primary production. Differences between the thaw and non‐thaw ponds were less marked at the primary consumer level. Daphnia pulex, which dominated the crustacean zooplankton community, did not respond to the higher omega‐3 availability in the thaw ponds but rather assimilated the high‐quality fatty acids equally in all ponds, possibly because their metabolic needs were already saturated. However, some lower quality terrestrial carbon compounds from permafrost ended up in the D. pulex body mass, resulting in a median allochthony of 18% based on fatty acid mixing model; non‐thaw ponds had median allochthony mixing model estimates of 8%. The high availability of algal resources seemed to prevent extensive zooplankton allochthony in subarctic thaw ponds.

中文翻译：

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多年冻土融化会刺激初级生产者，但对北极池中初级消费者的影响中等

冻冻的苔原土壤是地球上最大的有机碳库之一。气候变暖和相关的多年冻土融化将大部分碳释放到极地湖泊中，引起极端褐变，为异养微生物食物网提供了燃料。多年冻土碳如何影响食物链中较高的生物尚不清楚。利用溶解有机物的性质，总磷，叶绿素a，脂肪酸和稳定同位素，我们研究了永久冻土解冻对浮游食物网主要生产者和主要消费者的影响。我们采样了四个受永久冻土碳影响的北极解冻池塘，以及另外四个不受永久冻土影响的池塘。我们的结果强调了侵蚀和降解富含冰的多年冻土对养分和浮游藻类的刺激作用。相对于非融化池塘，冻土影响的淡水总磷浓度较高（分别为14.8和70.4 µg / L）。反过来导致较高的叶绿素a（2.7 vs. 45.2 µg / L）和ω-3脂肪酸含量（7.3 vs. 53.5 µg / L），尽管一次生产所需的光量明显减少。在主要消费者水平上，解冻池和非解冻池之间的差异较小。占主导地位的甲壳类浮游动物群落的水蚤（Daphnia pulex）对融化池塘中较高的omega-3利用率没有反应，而是在所有池塘中均等地吸收了优质脂肪酸，可能是因为它们的代谢需求已经饱和。然而，来自多年冻土的一些质量较低的陆地碳化合物最终在D. pulex中出现。体重，根据脂肪酸混合模型得出的中位异位体为18％；非融化池塘的异位混养混合模型估计中值为8％。藻类资源的高可用性似乎阻止了北极解冻池塘中广泛的浮游动物异源化。