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

气候引起的冰川退缩将影响冰川河流中大型无脊椎动物的组成，并导致α多样性和丰度的增加以及下游大型无脊椎动物的向上迁移。在北极地区，气候变化预计将导致重大的环境变化，雪对水生生态系统越来越重要，冰川融水的影响正在下降。对大型无脊椎动物组成的影响在很大程度上仍然没有得到解决，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年）的基础上，调查沿着北极冰川河流和雪流河流大型无脊椎动物的时间变化，Gíslason等人于1996年和1997年沿着北极河流维斯塔里河和奥斯塔里-约库尔萨河绘制大型无脊椎动物、水文物理和化学参数图。自这些第一次调查以来，水文和气候条件发生了重大变化。作为一个重复的调查，非生物变量电导率，水温，水位，DOC（浓度，吸光度、荧光），将在1996年和1997年的同一地点（21个），在为期两年的6个季节性采样活动（春、夏、秋）中，对稳定同位素、溶解硅、营养物（PO 4、NO3、NO2和NH 4）、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进行调查。为了今后监测冰川河流中的动物，正在测试和进一步开发环境DNA元条形码的创新和非侵入性方法。这种方法已经成功地应用于其他水生生态系统，但尚未在冰川河流。一系列统计技术（例如，单因素/双因素方差分析），以确定纵向变化的大型无脊椎动物组合之间的几个调查和检测环境驱动因素的差异。通过端元混合分析，将确定不同的水源及其相对径流贡献，从而可以评估气候变化引起的水源变化对大型无脊椎动物的影响。这种深入的跨尺度研究的水文生物学和地球化学性质的两个北极流不同的水文和时空动态将关闭知识差距的长期变化的纵向变化的大型无脊椎动物群落在北极冰川流。

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.