Mountain Lakes as Indicators of the Cumulative Impacts of Ultraviolet Radiation and other Environmental Stressors
High elevation lake ecosystems are regarded as potentially sensitive indicators of global change because of their cold and dilute abiotic environment, low biodiversity, poor functional redundancy, and relative lack of local human perturbations (Skjelkvâle and Wright 1998; Sommaruga 2001; Battarbee et al. 2002; Psenner et al. 2002). Mountain lakes located near treeline are expected to be the most responsive to long-term impacts of stratospheric ozone depletion and increased flux of solar ultraviolet-B radiation (UV-B; 290–320 nm), climatic warming, and other stressors because of sharp transitions in control processes (Fig. 1) associated with vegetation development and snowpack albedo (Vinebrooke and Leavitt 1998; 1999a; Fyke and Flato 1999). As detailed below, increased flux of solar UV-B and global warming may be already interacting to restructure food webs and biogeochemical cycles in many mountain lakes (Leavitt et al. 1997; Sommaruga-Wögrath et al. 1997).
KeywordsClimate change Dissolved organic matter Ecotonal sensitivity hypothesis Multiple stressors Paleoecology Treeline lakes Ultraviolet radiation
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