Department of Watershed Sciences, Utah State University, Logan, Utah, USA.
Department of Plant and Microbial Biology and the BioTechnology Institute, University of Minnesotagrid.17635.36, Saint Paul, Minnesota, USA.
mSphere. 2022 Dec 21;7(6):e0050322. doi: 10.1128/msphere.00503-22. Epub 2022 Nov 7.
Glaciers are rapidly receding under climate change. A melting cryosphere will dramatically alter global sea levels, carbon cycling, and water resource availability. Glaciers host rich biotic communities that are dominated by microbial diversity, and this biodiversity can impact surface albedo, thereby driving a feedback loop between biodiversity and cryosphere melt. However, the microbial diversity of glacier ecosystems remains largely unknown outside of major ice sheets, particularly from a temporal perspective. Here, we characterized temporal dynamics of bacteria, eukaryotes, and algae on the Paradise Glacier, Mount Rainier, USA, over nine time points spanning the summer melt season. During our study, the glacier surface steadily darkened as seasonal snow melted and darkening agents accumulated until new snow fell in late September. From a community-wide perspective, the bacterial community remained generally constant while eukaryotes and algae exhibited temporal progression and community turnover. Patterns of individual taxonomic groups, however, were highly stochastic. We found little support for our prediction that autotroph abundance would peak before heterotrophs. Notably, two different trends in snow algae emerged-an abundant early- and late-season operational taxonomic unit (OTU) with a different midsummer OTU that peaked in August. Overall, our results highlight the need for temporal sampling to clarify microbial diversity on glaciers and that caution should be exercised when interpreting results from single or few time points. Microbial diversity on mountain glaciers is an underexplored component of global biodiversity. Microbial presence and activity can also reduce the surface albedo or reflectiveness of glaciers, causing them to absorb more solar radiation and melt faster, which in turn drives more microbial activity. To date, most explorations of microbial diversity in the mountain cryosphere have only included single time points or focused on one microbial community (e.g., bacteria). Here, we performed temporal sampling over a summer melt season for the full microbial community, including bacteria, eukaryotes, and fungi, on the Paradise Glacier, Washington, USA. Over the summer, the bacterial community remained generally constant, whereas eukaryote and algal communities temporally changed through the melt season. Individual taxonomic groups, however, exhibited considerable stochasticity. Overall, our results highlight the need for temporal sampling on glaciers and that caution should be exercised when interpreting results from single or few time points.
冰川在气候变化下迅速消退。一个融化的冰冻圈将极大地改变全球海平面、碳循环和水资源供应。冰川拥有丰富的生物群落，以微生物多样性为主导，这种生物多样性会影响地表反照率，从而在生物多样性和冰冻圈融化之间形成反馈循环。然而，除了主要的冰盖之外，冰川生态系统的微生物多样性在很大程度上仍然未知，尤其是从时间的角度来看。在这里，我们在九个时间点上对美国雷尼尔山天堂冰川的细菌、真核生物和藻类进行了时间动态特征描述，这些时间点跨越了夏季融化季节。在我们的研究过程中，随着季节性积雪的融化和深色物质的积累，冰川表面逐渐变暗，直到 9 月下旬新雪降落。从整个群落的角度来看，细菌群落基本保持不变，而真核生物和藻类则表现出时间上的进展和群落更替。然而，个别分类群的模式高度随机。我们几乎没有证据支持我们的预测，即自养生物的丰度会在异养生物之前达到峰值。值得注意的是，雪藻出现了两种不同的趋势——一个丰富的早期和晚期季节的操作分类单元（OTU）和一个不同的 8 月峰值的中夏 OTU。总的来说，我们的结果强调了在冰川上进行时间采样以澄清微生物多样性的必要性，并警告说，当从单个或少数时间点解释结果时，应谨慎行事。
高山冰川上的微生物多样性是全球生物多样性中一个尚未充分探索的组成部分。微生物的存在和活动也会降低冰川的表面反照率或反射率，使它们吸收更多的太阳辐射并更快融化，这反过来又会促进更多的微生物活动。迄今为止，对山地冰冻圈中微生物多样性的大多数探索只包括单个时间点或只关注一个微生物群落（例如细菌）。在这里，我们在美国华盛顿州的天堂冰川上进行了夏季融化季节的整个微生物群落（包括细菌、真核生物和真菌）的时间采样。在整个夏季，细菌群落基本保持不变，而真核生物和藻类群落则在融化季节中发生了时间变化。然而，个别分类群表现出相当大的随机性。总的来说，我们的结果强调了在冰川上进行时间采样的必要性，并警告说，当从单个或少数时间点解释结果时，应谨慎行事。
