Division of Animal Structure and Function, Department of Cell Biology, University of Salzburg Hellbrunnerstraße 34, 5020, Salzburg, Austria.
Ecol Evol. 2013 Sep;3(9):2832-44. doi: 10.1002/ece3.679. Epub 2013 Jul 22.
Ongoing glacial retreat is expected to lead to numerous changes in glacier-fed rivers. This study documents the development of community composition of the hitherto widely neglected micro- and meiobenthos (MMB: bacteria, fungi, algae, protists, and meiofauna) in glacier rivers in response to the distinct habitat conditions driven by different stages of (de)glacierization. Our model is based on the glacier catchments of the Möll River (MC) and Kleinelendbach stream (KC), in the Austrian Alps, with 60% and 25% glacierization and glacier retreats of 403 and 26 m, respectively, since 1998. Analyses of overall catchment diversity and resemblance patterns showed that neither intense glacierization nor rapid deglacierization were predominant MMB determinants. This was ascribed to the specific environmental conditions at the MC, where the rapidly retreating Pasterze glacier has formed a harsh unstable proglacial, but also a benign floodplain area, with the former suppressing and the latter supporting the structural development of the MMB. Comparisons of similarly aged riverine habitats of the MC proglacial and the KC main channel further evidenced developmental suppression of the MMB (64 taxa) by the rapidly retreating MC glacier, unlike the moderate glacial retreat in the KC (130 taxa). Habitat conditions interacting with melt periods explained the differences in MMB resemblance patterns, which themselves differentially reflected the spatiotemporal habitat settings imposed by the different glacier activities. The varying glacial influences were represented by a glaciality index (GIm) based on water temperature, electrical conductivity, and stream bed stability. The taxonomic richness of nematodes, rotifers, algae, and diatoms was distinctly related to this index, as were most MMB abundances. However, the strongest relationships to the GIm were those of nematode abundances and maturity. Our observations highlight the intense response of the MMB to ongoing glacier retreat and the utility of a simple index to reveal such patterns.
预计冰川退缩将导致冰川补给河流发生许多变化。本研究记录了迄今为止广泛忽视的微小型底栖生物（MMB：细菌、真菌、藻类、原生动物和小型底栖动物）群落组成的发展，以应对由不同阶段的（冰川）消融所驱动的独特生境条件。我们的模型基于奥地利阿尔卑斯山莫尔河（MC）和克莱内伦巴赫溪流（KC）的冰川流域，自 1998 年以来，冰川化分别达到 60%和 25%，冰川退缩分别为 403 米和 26 米。对整个集水区多样性和相似性模式的分析表明，强烈的冰川化或快速的冰川消融都不是 MMB 的主要决定因素。这归因于 MC 特定的环境条件，在那里快速退缩的帕斯特泽冰川形成了恶劣不稳定的前缘，但也形成了良性的洪泛区，前者抑制了 MMB 的结构发展，后者支持了 MMB 的结构发展。对 MC 前缘和 KC 主河道具有相似年龄的河流生境的比较进一步证明，与 KC 中适度的冰川退缩（130 个分类群）不同，快速退缩的 MC 冰川对 MMB 的发育产生了抑制作用（64 个分类群）。与融化期相互作用的生境条件解释了 MMB 相似性模式的差异，这些差异反过来又反映了不同冰川活动所施加的时空生境环境。通过基于水温和电导率以及河床稳定性的冰川性指数（GIm）来代表不同的冰川影响。线虫、轮虫、藻类和硅藻的分类丰富度与该指数明显相关，大多数 MMB 的丰度也是如此。然而，与 GIm 最强的关系是线虫丰度和成熟度。我们的观察结果强调了 MMB 对正在进行的冰川退缩的强烈反应，以及使用简单指数来揭示这种模式的实用性。
