McMurdo Dry Valleys LTER - Antarctica
McMurdo Dry Valleys LTER
The McMurdo Dry Valleys (MDVs) (78°S, 162°E) represent the largest (4500 km^2) ice-free area on the Antarctic continent. The MDV landscape is a mosaic of glaciers, soil and exposed bedrock, and stream channels that connect glaciers to closed-basin, permanently ice-covered lakes on the valley floors. Mean annual air temperatures are cold (ranging from -15 to -30°C on the valley floors), and precipitation is low (~50 mm annual water equivalent as snow). Summer air temperatures typically hover around freezing and winter air temperatures are commonly < -40°C. While the water columns of the lakes are liquid and biologically active year round, glacial meltwater streams flow and soils thaw only during the austral summer. There are no vascular plants, but microbial mats are abundant in lakes and streams. Mat organisms are transported by wind onto glacier and lake ice surfaces where they actively metabolize in liquid water pockets (cryoconites) that form during the summer months. In the streams, which desiccate for ~10 months each year, cyanobacterial mats host extensive diatom and soil invertebrate communities. Lakes provide a habitat for diverse phototrophic and heterotrophic plankton communities that are adapted to annual light-dark cycles and temperatures near 0°C. Soils are inhabited by nematodes, rotifers, and tardigrades, all of which are metabolically active during summer. The McMurdo Dry Valleys LTER (MCM) began studying this cold desert ecosystem in 1993 and showed that its biocomplexity is inextricably linked to past and present climate drivers. In the fifth iteration of the MCM LTER program, we are working to determine how the MDVs respond to amplified landscape connectivity resulting from contemporary climate variation.
General Characteristics and Status