Macroinvertbrates as indicators of acidification of high-altitude Alpine lakes

High-altitude lakes, due to climatic factors, shallow soil cover, little vegetation, modest dimension of the watershed, long iced surface and rapid flushing rates are known to be particularly sensitive to atmospheric pollution (Wathne et al. 1995). In response to decreased atmospheric acid deposition, lakes in the Western Alps showed signs of chemical recovery since the mid 1990s (Rogora et al. 2003; Steingruber and Colombo, 2010). Neverthless, examples of biological recovery are still rare (Marchetto et al. 2004). Moreover, using benthic macroinvertebrates to assess acidification, for highaltitude Alpine lakes a specific method has not yet been developed. Unfortunately, because of the small data set (macroinvertebrate data from only 5 lakes in Southern Switzerland) the development of such a method goes beyond our possibilities. Instead, the aim of this study was to apply different already existing metrics to macroinvertebrate samples from lakes with different pH (from acid sensitive to alkaline), with the purpose to find which reflects best differences in lake acidity in order to improve temporal assessment of acidification through benthic macroinvertebrates in high-altitude Alpine lakes in Southern Switzerland.