First approach to the description of phytoplankton and periphytic communities in freshwater bodies of South Patagonia (49°S), Argentina

RAYÓ, MARÍA CECILIA; ESQUIUS, KARINA SOLEDAD; TONELLO MARCELA

Bariloche, Rio Negro

Congreso; IAL - IPA 2022; 2022

Intarnational Association of Limnogeology e International Paleolimnology Association

The limnological and ecological information of water bodies located on the eastern slope of South Patagonian Andes (49°S) is scarce. Particularly, understanding the phytoplankton and periphyton algae components will enrich the interpretation and discussion of the evolution of these water bodies from the Late Holocene to the present. The algae remains presented in the fossil record as well as in lake sediment samples are known as non-pollen palynomorphs (NPPs), and their identification constitutes an important paleoenvironmental contribution to environmental reconstructions. Thus, the aim of this work is to characterize the phytoplankton and periphyton community present in water bodies and the NPPs in surface sedimentary samples, with emphasis on the diversity of cyanobacteria and chlorophyta algae. Three freshwater bodies (Laguna Gemelas Este, Laguna Gemelas Oeste and Laguna Chiquita) located between 400 and 1100 m.a.s.l. at Los Glaciares National Park, were sampled during the 2020 and 2022 summer fieldwork. At each lake, phytoplankton samples were obtained with plankton net whereas periphyton was removed by scraping off the predominant littoral vegetation. Both samples were observed under an optical microscope. The water-sediment interface samples were taken with a gravity corer and received a conventional palynological treatment. The limnological measurements were registered in situ: water temperature, pH, electrical conductivity, maximum depth and transparency. Phytoplankton and periphyton communities presented similar taxonomic composition and despite the low counts, the diversity of chlorophyta algae was significant. Dominant taxa were different among water bodies and communities sampled, including Desmidiaceae genera (Cosmariumand Closterium) and volvocine chlorophytes in phytoplankton; filamentous chlorophytes and cyanobacteria in periphyton; and Pediastrum and zygospores of Desmidiaceae and Zygnematales in water-sediment samples. These data constitute the first approach to the description of phytoplankton and periphyton communities in water bodies of the region.