| Summary: | First discovered by Robert Scott' s expedition (1904-1906), the McMurdo Dry Valleys are now visited every year by numbers of scientists of different disciplines. The McMurdo Dry Valleys represent the largest ice-free region in Antarctica, which corresponds to 2.4% of the continental area (Fountain et al., 1998). The Dry Valleys are the driest and coolest deserts on Earth with: 0.6 crn/year water equivalent at Lake Vanda (Bromley, 1985 in Fountain et al., 1999) and an average air temperature over the valleys floor of around -200C and 1.40C over the warmest months (Fountain et al., 1998). Their most important characteristic is the domination of arid soils over ice sheet, which rules the rest of the continent The presence of soil plays a crucial role for the entire ecosystem of the Dry Valleys by considerably reducing the surface albedo compared to the adjacent ice-covered area. Thompson et al. (1971) discovered that the albedo difference occurring in the Dry Valleys had for consequence a rise of temperature of 70C warmer over the summer and a 50C to 70C cooler during the winter. The result of this higher absorbtivity of solar radiation let the Dry Valleys be one of the only areas where an annual heat balance is positive in Antarctica. The understanding of the relationship between the DIY Valleys streams and lakes and the ecosystems generated by their presence is, in a way, controled by solar radiation since streams are dictated by the quantity and timing of austral summer (Dana and Wharton Jr., 1998). This review paper illustrates the relationship between glaciers, streams and lakes that form a particular ecosystem in one ofthe only ice-free area of Antarctica. The Onyx River, located in the Wright Valley, is used to symbolise these relations. First discovered by Robert Scott' s expedition (1904-1906), the McMurdo Dry Valleys are now visited every year by numbers of scientists of different disciplines. The McMurdo Dry Valleys represent the largest ice-free region in Antarctica, which corresponds to 2.4% of the ...
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