The McMurdo Dry Valleys (MDVs) are a cold desert region of Antarctica supporting terrestrial andÌýaquatic ecosystems that host microbial food webs, with few species of primitive animals (like tardigrades and nematodes), and no vascular plants or vertebrates. The organisms that persist here have adapted to the cold, dark, and arid conditions that prevail for all but a brief period in the austral summer. In the summer, soils warm and glacial meltwater flows through streams into the open moats of permanently ice-covered, closed-basin lakes. Because of this energy, water, and ecological connectivity, most biological activity across the landscape occurs in summer. Through the winter, or polar night (6 months of darkness), glaciers, streams, and soil biota are inactive until sufficient light, heat, and liquid water return, while lake communities remain active all year.
The McMurdo Dry Valleys LTER (MCM LTER) has studied this ecosystem since 1993. The last two cycles of the MCM LTER have documented dynamic landscape and ecosystem responses to recent warming and enhanced connectivity. Over the past 30 years, the MDVs have been disturbed by cooling, heatwaves, floods, rising lake levels, and permafrost and lake ice thaw. Considering the clear ecological responses to this variation in physical drivers, and climate models predicting further warming and more precipitation, the MDV ecosystem sits at a threshold between the familiar extreme cold and dry conditions and an uncertain future. In MCM6, we will examine how changes in the temporal variability of ecological connectivity interact with the existing landscape legacies that have defined habitat suitability and biogeochemical cycling for millennia.
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