Longitudinal variation of macroinvertebrate assemblages in Icelandic arctic glacier-fed and snow-fed streams: changes and their environmental drivers – a comparison after 26 years

冰川退缩会影响冰川河流中大型无脊椎动物的组成，导致α-多样性和丰度增加，并导致下游大型无脊椎动物向上迁移。在气候变化预计将导致重大环境变化的北极地区，雪对水生生态系统变得越来越重要，冰川融水的影响正在减弱。对大型无脊椎动物组成的影响在很大程度上仍未得到解决，主要是因为在北极地区也缺乏长期研究。因此，本研究项目将在Gíslason等人（2001）1996年和1997年绘制北极河流Vestari河和Austari-Jökulsá河沿岸大型无脊椎动物、水物理和化学参数图的基础上，研究北极冰川供水河流和雪供水河流沿线大型无脊椎动物的时间变化。自从第一次调查以来，水文和气候条件发生了重大变化。通过对非生物变量电导率、水温、水位、DOC（等）的反复研究。将在1996年和1997年的同一地点（21）进行为期两年的6次季节性采样活动（春、夏、秋），调查稳定同位素、溶解二氧化硅、营养物质（PO4、NO3、NO2和NH4）、离子（Ca、Mg、Na、K）、叶绿素α和悬浮沉积物以及大型无脊椎动物。为了将来对冰川河流中的动物进行监测，正在测试和进一步开发一种创新的、非侵入性的环境dna元条形码方法。这种方法已经成功地应用于其他水生生态系统，但尚未应用于冰川河流。将应用一系列统计技术（例如，单向/双向方差分析），以确定几次调查之间大型无脊椎动物群落纵向变化的差异，并检测环境驱动因素。通过端元混合分析确定不同水源及其相对径流贡献，从而评估气候变化引起的水源变化对大型无脊椎动物的影响。对北极两种不同水文条件下河流的水文生物学和生物地球化学特征及其时空动态进行深入的跨尺度研究，将填补北极冰川补给河流中大型无脊椎动物群落纵向变化长期变化的知识空白。

Climate-induced retreat of glaciers will affect the macroinvertebrate composition in glacier‐fed rivers and lead to an increase in α-diversity and abundance as well as to an upward migration of downstream macroinvertebrates. In Arctic regions, where climate change is expected to cause major environmental changes, snow is becoming increasingly important for aquatic ecosystems, and the influence of glacier meltwater is declining. The consequences for macroinvertebrate composition are still largely unresolved, mainly because long-term studies in Arctic regions are also lacking. Therefore, this research project will investigate temporal changes in macroinvertebrates along an Arctic glacier-fed river and a snow-fed river on the basis of Gíslason et al. (2001) who mapped macroinvertebrate, hydrophysical and -chemical parameters in 1996 and 1997 along the arctic rivers Vestari- and Austari-Jökulsá River. Since these first investigations the hydrological and climatic conditions have changed significantly. As a repetitive investigation the abiotic variables electrical conductivity, water temperate, -level, DOC (conc., absorbance, fluoresce.), stable isotopes, dissolved silica, nutrients (PO4, NO3, NO2, and NH4), ions (Ca, Mg, Na, K), chlorophyll α and suspended sediment as well as macroinvertebrates will be investigated at the same locations (21) as in 1996 and 1997 during 6 seasonal sampling campaigns (spring, summer, autumn) over a time period of two years. For future monitoring of fauna in glacial rivers, the innovative and non-invasive method of environmental DNA-metabarcoding is being tested and further developed. This approach has already been successfully applied in other aquatic ecosystems, but not yet in glacier-fed rivers. A range of statistical techniques (e.g., one-way/two-way ANOVA) will be applied, to identify differences in longitudinal changes of macroinvertebrate assemblages between the several investigations and to detect environmental drivers. Different water sources and their relative runoff contribution will be identified by end-member mixing analysis, whereby the impact of climate change induced variations of water sources on macroinvertebrates can be assessed. This intensive cross-scale study of the hydrobiological and biogeochemical properties of two Arctic streams with different hydrology and their spatial and temporal dynamics will close the knowledge gap regarding the long-term change of longitudinal variation of macroinvertebrate communities in arctic glacier-fed streams.