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Catalan, Lakes as witnesses of Global Change in Mountains
Submitted by share-everest on Wed, 04/30/2008 - 14:53.
High mountain lakes are among the ecosystems with larger similarities throughout the planet. The low permeability of crystalline rocks favours the presence of lakes and, because orogenesis is the main source of this bedrock type, most of the large and high ranges of the World have an associated lake district.
Despite their apparent marginal role in the Earth system, high-mountain lakes are particularly suitable for studies on certain environmental and ecological topics, and for this reason, the scientific community has paid attention to them beyond to what could be expected from their quantitative relevance.
The particular location of high mountain lakes determines a number of environmental conditions that are traditionally considered extreme for life: extreme dilution, high radiation (including UV-B), long dark ice-covered periods and cold waters.
The degree of those extreme conditions changes from place to place and, thus, high mountain lake districts are usually a mosaic of highly diverse lakes, diversity which is highly coherent with the characteristics of their catchments, because mountain lakes are small water bodies where matter loadings from the catchment are fundamental in determining the lake characteristics.
Catchments are relatively small compare to low land lakes, as a consequence, atmospheric loadings tend to be also significant to determine the characteristics of water runoff, and thus lake water ones.
If we combine the sensitivity of mountain lake ecosystems to external forcing with their remoteness from areas of high human activity, in turns out that high mountain lakes are excellent sentinels and recorders of past and present global environmental changes. Particularly, atmospheric pollution and climate fluctuations are well recorded and provide evidence of the present situation and references from the past.