Center for Applied Geoscience, Eberhard Karls University of Tübingen, Schnarrenbergstr. 94-96 72076 Tübingen, Germany.
Department of Earth Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Sonneggstrasse 5 NO D 51.3 8092 Zürich, Switzerland.
FEMS Microbiol Ecol. 2022 Jul 13;98(7). doi: 10.1093/femsec/fiac075.
Glacial melt-down alters hydrological and physico-chemical conditions in downstream aquatic habitats. In this study, we tested if sediment-associated microbial communities respond to the decrease of glaciers and associated meltwater flows in high-alpine lakes. We analyzed 16 lakes in forefield catchments of three glaciers in the Eastern Swiss Alps on physico-chemical and biological parameters. We compared lakes fed by glacier meltwater with hydrologically disconnected lakes, as well as "mixed" lakes that received water from both other lake types. Glacier-fed lakes had a higher turbidity (94 NTU) and conductivity (47 µS/cm), but were up to 5.2°C colder than disconnected lakes (1.5 NTU, 26 µS/cm). Nutrient concentration was low in all lakes (TN < 0.05 mg/l, TP < 0.02 mg/l). Bacterial diversity in the sediments decreased significantly with altitude. Bacterial community composition correlated with turbidity, temperature, conductivity, nitrate, and lake age and was distinctly different between glacier-fed compared to disconnected and mixed water lakes, but not between catchments. Chemoheterotrophic processes were more abundant in glacier-fed compared to disconnected and mixed water lakes where photoautotrophic processes dominated. Our study suggests that the loss of glaciers will change sediment bacterial community composition and physiology that are unique for glacier-fed lakes in mountain and polar regions.
冰川融化改变了下游水生栖息地的水文和物理化学条件。在这项研究中，我们测试了沉积物相关的微生物群落是否会对高山湖泊中冰川减少和相关融水流量的变化做出响应。我们分析了瑞士东部阿尔卑斯山三个冰川前流域的 16 个湖泊的理化和生物参数。我们比较了由冰川融水补给的湖泊与水文上不连通的湖泊，以及同时接受这两种湖泊供水的“混合”湖泊。冰川补给的湖泊浊度（94 NTU）和电导率（47 µS/cm）更高，但比不连通的湖泊低 5.2°C（1.5 NTU，26 µS/cm）。所有湖泊的养分浓度都很低（TN < 0.05 mg/l，TP < 0.02 mg/l）。沉积物中的细菌多样性随海拔高度显著降低。细菌群落组成与浊度、温度、电导率、硝酸盐和湖泊年龄相关，与冰川补给湖泊相比，不连通和混合水湖泊的细菌群落组成明显不同，但与集水区无关。与不连通和混合水湖泊相比，冰川补给湖泊中化能异养过程更为丰富，而光自养过程占主导地位。我们的研究表明，冰川的消失将改变高山和极地地区冰川补给湖泊中独特的沉积物细菌群落组成和生理特性。
