Response of Alpine lakes to major environmental gradients, as detected through planktonic, benthic and sedimentary assemblages

MARCHETTO,A., ROGORA,M, BOGGERO,A., LAMI, A., LOTTER,A., TOLOTTI,M., THIES,H., PSENNER,R., MASSAFERRO, J AND BARBIERI, A.

JOURNAL OF PALEOLIMNOLOGY

Springer

Año: 2007

0921-2728

Abstract A survey of 72 oligotrophic, clearwater high mountain lakes in the Alps (Italy, Austria and Switzerland) was carried out in 2000 to identify biological indicators useful for lake classification. Samples were collected for water chemistry, phytoplankton, epilithic diatoms, littoral macroinvertebrates and zooplankton. Surface sediments were analyzed for algal pigments, metals, cladocera, chironomid and diatom remains. A multivariate analysis of morphometric, geographical and chemical variables identified two main gradients: (1) a geological gradient, from alkaline lakes on carbonaceous watershed to acidic lakes on granitic watersheds, and (2) an altitude gradient  also including variables related to temperature, lake size and trophic status. The analysis of the biological data showed that the geological gradient is related to the composition of phytobenthos, as well as sedimentary diatoms and chironomids, while the morphologic gradient is mainly related to the composition of algal pigments phytoplankton and macrozoobenthos. The results were used to provide a lake typology for this ecoregion, and finally to identify indicator taxa or variables