The objective of this study was to evaluate how stream water nutrient concentrations influence biofilm accrual in streams draining mountainous permafrost headwaters. We selected six stream locations in the Zackenberg area (NE Greenland, 74°N) subjected to a gradient in the areal contribution of different geomorphological units in the watersheds and channel stability. We used nutrient diffusing substrates to evaluate biofilm growth (autotrophic and total biomass). We found elevated stream nitrate concentrations in samples from upstream reaches draining larger areas of solifluction sheets and bare rock and with higher channel instability. Nitrate had the highest standardized effect on autotrophic biofilm growth on control disks. However, stream biofilm growth was not nutrient limited as shown by the absence of an increase in biofilm biomass as a response to the experimental nutrient additions. The response to nutrient additions via diffusing substrates depended on the altitude gradient. Overall, our results showed stream nitrogen availability to be one of the main drivers of algal biofilm accrual in high‐Arctic streams, suggesting that the predicted changes in nutrient exports induced by climate change will have strong impacts on the biogeochemistry and ecological functioning of high‐Arctic streams.

中文翻译：

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东北格陵兰山区多年冻土集水区的两条水流中生物膜的生长

这项研究的目的是评估溪水养分浓度如何影响山区多年冻土源头排水的溪流中生物膜的累积。我们在Zackenberg地区（NE格陵兰岛，北纬74°）中选择了六个溪流位置，这些流域受流域中不同地貌单元的面积贡献和河道稳定性的梯度影响。我们使用了营养扩散基质来评估生物膜的生长（自养和总生物量）。我们发现从上游到达的样品中流态硝酸盐浓度升高，流失了较大的固溶层和裸岩，且通道不稳定性更高。硝酸盐对对照盘上自养生物膜生长的标准化作用最高。然而，流中生物膜的生长不受营养物的限制，如不存在对实验营养物添加作出反应的生物膜生物量增加所表明的。通过扩散基质对养分添加的响应取决于海拔梯度。总体而言，我们的结果表明，河水氮的有效性是高北极河水藻类生物膜积聚的主要驱动力之一，这表明气候变化导致的营养物出口预计变化将对高海拔河床的生物地球化学和生态功能产生重大影响。北极溪流。