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

RAYÓ M C; ESQUIUS K S; TONELLO M S

Bariloche

Congreso; IAL IPA JOING MEETING 2022; 2022

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