Carbon Transformations in a Perennially Ice-Covered Antarctic Lake

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Abstract
© 1999 American Institute of Biological Sciences.Autotrophic production of organic carbon and its subsequent heterotrophic transformations drive biogeochemical reactions and influence species abundance and diversity in all ecosystems. The timing and magnitude of organic carbon production is particularly critical in desert ecosystems, where a paucity of liquid water, together with extremes in temperature, limits the period when biological activity can exist. Polar desert systems have additional stresses imposed on them by amplified seasonal patterns in sunlight. The McMurdo Dry Valleys of Antarctica is one of the most extreme deserts on the planet, with precipitation of less than 10 cm·yr−1and an average annual air temperature near −20 °C (range from approximately −55 °C to −5 °C; Clow et al. 1988). These valleys, which are located adjacent to McMurdo Sound (76.5–78.5° S, 160–164.5° E), form the largest ice-free region (approximately 4500 km2) on the Antarctic continent...