The McMurdo Dry Valleys (MDVs), Antarctica, represent a cold, desert ecosystem poised on the threshold of melting and freezing water. The MDVs have experienced dramatic signs of climatic change, most notably a warm austral summer in 2001–2002 that caused widespread flooding, partial ice cover loss and lake level rise. To understand the impact of these climatic disturbances on lake microbial communities, we simulated lake level rise and ice-cover loss by transplanting dialysis-bagged communities from selected depths to other locations in the water column or to an open water perimeter moat. Bacteria and eukaryote communities residing in the surface waters (5 m) exhibited shifts in community composition when exposed to either disturbance, while microbial communities from below the surface were largely unaffected by the transplant. We also observed an accumulation of labile dissolved organic carbon in the transplanted surface communities. In addition, there were taxa-specific sensitivities: cryptophytes and Actinobacteria were highly sensitive particularly to the moat transplant, while chlorophytes and several bacterial taxa increased in relative abundance or were unaffected. Our results reveal that future climate-driven disturbances will likely undermine the stability and productivity of MDV lake phytoplankton and bacterial communities in the surface waters of this extreme environment.

中文翻译：

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来自近地表水域的南极湖浮游植物和细菌对气候驱动的干扰表现出高度敏感性

南极洲的麦克默多干谷 (MDV) 代表了一个寒冷的沙漠生态系统，处于融化和结冰的边缘。MDV 经历了气候变化的显着迹象，最显着的是 2001-2002 年温暖的南方夏季，造成大范围的洪水、部分冰盖流失和湖水位上升。为了了解这些气候扰动对湖泊微生物群落的影响，我们通过将透析袋微生物群落从选定深度移植到水柱中的其他位置或开放水域周边护城河来模拟湖泊水位上升和冰盖流失。居住在地表水 (5 m) 中的细菌和真核生物群落在受到任何一种干扰时都会表现出群落组成的变化，而来自地表以下的微生物群落在很大程度上不受移植的影响。我们还观察到移植地表群落中不稳定溶解有机碳的积累。此外，还有类群特异性的敏感性：隐藻和放线菌对护城河移植特别敏感，而叶绿体和几种细菌类群的相对丰度增加或不受影响。我们的结果表明，未来气候驱动的干扰可能会破坏这种极端环境地表水中 MDV 湖泊浮游植物和细菌群落的稳定性和生产力。而叶绿素和一些细菌类群的相对丰度增加或不受影响。我们的结果表明，未来气候驱动的干扰可能会破坏这种极端环境地表水中 MDV 湖泊浮游植物和细菌群落的稳定性和生产力。而叶绿素和一些细菌类群的相对丰度增加或不受影响。我们的结果表明，未来气候驱动的干扰可能会破坏这种极端环境地表水中 MDV 湖泊浮游植物和细菌群落的稳定性和生产力。