Analysis of microbial mats and cyanobacteria from the laguna Amarga, Torres del Paine National Park, Chile

Abstract

This study is based on cyanobacterial and sedimentary investigations of the microbial mats formed at Laguna Amarga, located at the southernmost part of South America, specifically in the Chilean Torres del Paine National Park. The Torres del Paine’s natural and geological richness is composed by large extensions of native forests, lakes, fjords and millenary glaciers presided by Paine range and Patagonian Andes. It was created in 1959 and declared Biosphere World Reserve by UNESCO in 1978. In the area, it is common to observe Late Jurassic, Cretaceous and Miocene outcrops with glacial lineations evidencing the ice retreat. The Laguna Amarga is a shallow lake with a basin area of 3,18 km2 and the habitat for extensive colonies of algae and microbial mats. On the eastern shore stromatolites with nodular, bulbous, stratiform and domal forms are found. Analyses of the microbial mats allowed the identification of 25 species of cyanobacteria. The families Synechococcaceae Anagnostidis & Komárek 1995 (32%) and Chroococcaceae Nägeli 1849 (32%) were de most frequent in the material. The microbial mats of this lake may be produced mainly by the spherical cyanobacteria. The formation of microbial mats is controlled by the high frequency of cyanobacteria and by environmental factors. The correct interpretation of the microbial mats and their features and also the environmental conditions where they are formed are important to understand analogous structures in the past and could be applied in the interpretation of ancient microbial mats.

Key words: hypersaline lagoon, microbial mats, cyanobacteria, Laguna Amarga, Chile.