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Ecosystem development of streams lengthened by rapid glacial recession

机译：冰川快速衰退延长了河流的生态系统发展

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Glaciers worldwide are receding rapidly, thereby causing the lengthening of stream channels below glaciers. In this study, we recorded habitat properties and macroinvertebrates colonizing newly formed channels below 8 different glaciers in the Swiss Alps. Six glacial streams sampled in 1998 were re-sampled in 2009 and 2011, with sites formerly at the glacial snout also sampled in later years. Glacial recession resulted in streams being lengthened by 160 to 480 m between 1998 and 2009, and by 50 to 1305 m between 2009 and 2011. Newly formed streams near glacial snouts also were up to 100+ m higher in elevation than those in 1998. Sites sampled at the glacial snout in 1998 had 2-4 degrees C higher summer water temperatures in 2009 and 2011. Sites in 2009 and 2011 typically had higher pH, phosphorus constituents (PP, SRP), and turbidity values than in 1998, whereas nitrate levels were lower. The biomass (AFDM) of periphyton and benthic organic matter at most sites remained similar among years, although periphyton was highest at Morteratsch sites in 2011. In contrast, seston levels were up to ten-fold higher in later years than in 1998, likely reflecting the increased turbidity from glacial meltwaters (e.g., scouring). Most sites had similar average macroinvertebrate densities and taxon richness regardless of the year sampled, indicating newly formed channels were quickly colonized. The most common macroinvertebrate was Chironomidae (mostly Diamesinae, although chironomid relative abundances decreased by half at most sites between 1998 (50-90% of the composition) and 2011 (20-50% of the composition). Other common taxa in later years included various stoneflies (Leuctra spp., Protonenmra spp., Nemoura spp.), mayflies (Baetis alpinus, Rhithrogena loyolaea), and Oligochaeta. An NMDS analysis of the macroinvertebrate assemblages revealed that sites within a glacier catchment differed both within the year sampled as well as between years. This study documents that recently lengthened glacial streams are quickly colonized by periphyton and macroinvertebrates and that succession patterns (spatial and temporal) may be important in these systems. Further research is needed to determine the mechanistic basis underlying colonization dynamics and succession patterns in glacial streams as glaciers continue to recede.
机译：世界范围内的冰川正在迅速消退，从而导致冰川下方的河道延长。在这项研究中，我们记录了瑞士阿尔卑斯山8个不同冰川以下新形成的河道定居的栖息地特性和大型无脊椎动物。 1998年采样的6条冰川流在2009年和2011年进行了重新采样，以前在冰川口中的站点也在随后的几年中采样。冰川退缩导致河流在1998年至2009年之间延长了160至480 m，在2009年至2011年之间延长了50至1305 m。靠近冰川口的新形成的河流海拔也比1998年高出100多米。在1998年和2011年的冰河口采样中，夏季水温升高了2-4摄氏度。与1998年相比，2009年和2011年的站点的pH，磷成分（PP，SRP）和浊度值通常较高，而硝酸盐水平较高较低。尽管2011年Morteratsch地点的浮游生物最高，但多数地点的浮游生物和底栖有机物的生物量（AFDM）多年来仍相似。相比之下，后期的血清素水平比1998年高出十倍，这可能反映了冰川融水增加的浊度（例如冲刷）。无论取样年份如何，大多数地点的平均无脊椎动物密度和分类单元丰富度都差不多，这表明新形成的渠道很快就被殖民了。最常见的大型无脊椎动物是猫科（主要为Diamesinae，尽管在1998年（占组成的50-90％）至2011年（占组成的20-50％）的大多数地方，猫科动物的相对丰度下降了一半。各种石蝇（Leuctra属，Protonenmra属，Nemoura属），may（Baetis alpinus，Rhithrogena loyolaea）和Oligochaeta。对大型无脊椎动物集合的NMDS分析表明，冰川集水区内的位点在所采样的年份内也有所不同。这项研究表明，最近延长的冰川流很快被周生植物和大型无脊椎动物定殖，并且演替模式（时空分布）在这些系统中可能很重要，需要进一步的研究来确定定殖动态和演替模式的机理基础随着冰川的消退，冰川流中

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