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Research Objectives:
This project is one of two soil productivity components of McMurdo LTER (Ross Virginia, B-423-M, and Diana Wall, B-424-M). They have been studying soil biodiversity and ecosystem functioning in the Dry Valleys since 1989. Antarctic soils are the oldest, coldest, and driest on Earth and share similarities with the arid soils of the Jornada and Sevilleta LTER sites. The soils found in the McMurdo Dry Valleys are poorly developed, coarse-textured, and often have high salinities. They also have the lowest organic carbon and biological activity of any soils on this planet. The physical and chemical environment of Antarctic soils varies along gradients of temperature, moisture, organic matter content created in part by legacies of past climates.
No other soil systems are known to exist in which nematodes represent the top of the food chain and where food webs are as simple in structure. The nematode community in the Dry Valley soils consists of an endemic species Scottnema lindsayae , a microbial feeder (bacteria and yeast), Plectus antarcticus, a bacterial feeder, and Eudorylaimus antarcticus, an omnivore-predator. Because nematodes are aquatic animals, moisture is a more important factor for survival in Antarctica than low temperature. Moisture from melting snow and streams is available to soils only intermittently, so organisms must be capable of prolonged survival with limited moisture and temperatures below freezing. Nevertheless, nematodes are ideally suited for survival in this extreme environment. They can enter a survival state, anhydrobiosis, for extended periods. This effectively decouples them from the nutrient cycle, which may contribute to the extremely slow rate of nutrient and carbon exchange in the MCM.
The group will continue to maintain (through application of water and nutrients), monitor (soil moisture and temperature) and sample (soils) in our various long-term experimental plots near Lakes Fryxell, Hoare and Bonney. The overall goal is to determine the impacts of natural factors and those associated with potential climate change on the abundance, distribution, and diversity of soil biota. Project team members will collect samples and conduct experiments in the Dry Valleys when biological activity in soil is at a peak in December/January. In Crary Lab, they will process and analyze soils and sediments samples.
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