In a changing climate, Arctic streams are expected to show more influence from snowmelt, rainfall and groundwater, and less domination from glacial meltwater sources. Snowmelt streams are characteristic features of Arctic ecosystems, yet our current understanding of longitudinal patterns in benthic macroinvertebrate assemblages in these systems is limited when compared to glacier-fed systems. This study characterised longitudinal patterns of macroinvertebrate communities in snowmelt streams in northeast Greenland to provide novel insights into Arctic stream communities as dominant water sources shift with climate change. Benthic macroinvertebrates and environmental variables were sampled at three sites along five streams. Taxa diversity, evenness and abundance were expected to increase with distance from the stream source due to enhanced channel stability and warmer water temperature. This expectation for diversity and evenness was found in two streams, but abundance was up to ten times higher at the upstream sites compared to downstream, where biofilm biomass and ionic load were also highest. Here communities were largely dominated by the genus Eukiefferiella (Chironomidae). In the other three streams, no clear pattern in longitudinal macroinvertebrate community composition was evident due to low channel stability along the entire stream length. This study highlights the considerable variation in macroinvertebrate zonal distribution between snowmelt streams in northeast Greenland. A change towards more snowmelt-dominated streams in the Arctic could lead to shifts in the longitudinal organisation of macroinvertebrate community assemblages and the dominant species as a function of channel stability characteristics.

中文翻译：

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格陵兰岛东北部融雪溪流中大型无脊椎动物的纵向分布：了解生物物理控制

在不断变化的气候中，预计北极溪流将受到融雪、降雨和地下水的更大影响，而冰川融水源的支配地位将减弱。融雪溪流是北极生态系统的特征，但与冰川喂养系统相比，我们目前对这些系统中底栖大型无脊椎动物组合纵向模式的理解是有限的。这项研究表征了格陵兰岛东北部融雪溪流中大型无脊椎动物群落的纵向模式，以提供对北极河流群落的新见解，因为主要水源随着气候变化而变化。在五个溪流的三个地点对底栖大型无脊椎动物和环境变量进行了采样。分类群多样性，由于河道稳定性增强和水温升高，预计均匀度和丰度会随着距河流源头的距离而增加。在两条溪流中发现了这种对多样性和均匀性的期望，但上游站点的丰度比下游高十倍，下游的生物膜生物量和离子负载也最高。这里的群落主要由 Eukiefferiella（摇蚊科）属主导。在其他三个溪流中，由于沿整个溪流长度的通道稳定性较低，因此没有明显的纵向大型无脊椎动物群落组成模式。这项研究强调了格陵兰岛东北部融雪溪流之间大型无脊椎动物带状分布的显着差异。