The McMurdo Dry Valleys, Antarctica: Terrestrial and aquatic ecosystems responding to climatic events that enhance hydrologic transport acress the landscape
Wednesday, 17 December 2014: 8:30 AM
The McMurdo Dry Valleys of Antarctica is comprised of alpine and terminal glaciers, large expanses of patterned ground, and permanently ice-covered lakes in the valley floors, which are linked by glacial meltwater streams that flow during the austral summer. These valleys were first explored by Robert Scott and his party in 1903. In 1968 the New Zealand Antarctic Program began a gauging network on the Onyx River, a 32 km river in Wright Valley which is the longest river in Antarctica. As part of the McMurdo Dry Valleys Long-Term Ecological research project our research group has monitored meteorological conditions, glacial mass balance, lake level and streamflow in the adjacent Taylor Valley. The extent of liquid water throughout the landscape is strongly controlled by summer climate, and the availability of liquid water in turn is a limitation to the microscopic life that is present in the diverse habitats in the valleys. We have studied the responses of soil, lake, stream and cryoconite ecosystems through a sustained cooling period that has been driven by atmospheric changes associated with the ozone hole. In the past decade, this cooling period appears to have ceased and summer conditions have become more variable. Three warm sunny summers have occurred since 2001/02. These conditions have created weeks long "flood events" in the valleys, causing wet areas to emerge in the soils, thermokarsting in some stream channels and increases in lake level. These flood events can be considered as pulse events that drive an increase in ecosystem connectivity, changing rates of biogeochemical processes and the distribution of biota. Collectively the ecosystems of the McMurdo Dry Valleys are highly responsive to dynamic climatic influences associated with the ozone hole and global warming.