Hydrology At The Bottom Of The World - A Key Influence Of Ecosystem Dynamics In The McMurdo Dry Valleys, Antarctica
Gooseff, Michael 1
1 Penn State University
In numerous extreme environments on Earth, the notion that “where there is water, there is life” has generally held. The ‘barren’ landscape of the McMurdo Dry Valleys, Antarctica, characterized by harsh conditions (e.g., air temperature ranges from <-40⁰C to >0⁰C), is no exception. Less than 10 cm of precipitation (all snow) falls annually, though snow patches collect in topographic lees on valley floors, potentially providing soil moisture across broad portions of the landscape. Stream flow is produced from glacial melt and provides water to maintain lakes on the valley floors. Thus, surface energy balance on glaciers is a primary control on the amount and timing of liquid water. In most Dry Valley lakes, liquid water is found beneath perennial ice covers year-round. In the austral summer, liquid water is regularly found in and around stream channels and open water occurs around the edges of lakes. The presence of liquid water in streams and soils provides unique habitats that host communities of invertebrates, algae, and microbes. These communities readily process carbon, nitrogen, and phosphorous despite low temperatures and long periods (>9 months annually) without liquid water. In this presentation we will discuss the hydrologic cycle of the McMurdo Dry Valleys and its controls on fluvial and terrestrial ecosystem structure and function. In particular, we will explore the roles of snow, stream flow, and riparian soil moisture in controlling ecosystem dynamics in this polar desert.