Encontro Ciência July. Antarctic Deserts where Life Exists at its Limits. Catarina Magalhães

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1 Antarctic Deserts where Life Exists at its Limits Catarina Magalhães

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3 Latitudinal temperature gradient Latitudinal precipitation gradient

4 Extreme Environment Low temperatures Low available water and humidity Abundant freeze-thaw cycles High salinity Low Carbon and Nutrient concentrations High ultra-violet radiation and winds Dramatic physical and chemical gradients Photo by Catarina Magalhães Photo by Photo Catarina Photo by Peggy by Magalhães Nita O Day Smith Organisms that survive in these extremely cold and arid ecosystems are considered to be subject to more environmental stresses than any other desert on the planet.

5 First scientific expeditions we have seen no living thing, not even a moss or lichen Robert Scott 1903 Dry Valleys were described as sterilized environments until the seventies. Antarctica Dry Valleys

6 As the environmental constraints increase, fewer organisms Springtails possess the necessary adaptations Nematodes Invertebrates Vegetation Rotifers Lichen Algae Springtails Moss Photo by Nasa Earth Observatory Mites Tardigrades

7 Cary et al Nature Reviews Prokaryotes dominate these extreme ecosystem

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10 High spatial pattern of biota due to extreme heterogeneity of biogeochemical soil properties Historical landscape changes were identified as keystone drivers of the distribution of taxa in the Dry Valleys.

11 Drift age / Osmotic Stress Soil salinity as a function of drift age, is the keystone driver of presence and distribution of biota in the Darwin Mountains of continental Antarctica. Younger drifts Weakly developed soils Less salts content Lower level of osmotic tolerance more complex communities Biota diversity

12 The antagonistic relationship between drift ages and diversity is particularly evident for bacteria and cyanobacteria.

13 MV Elevation BP BV UW Beacon Valley MV BP BV Cond. Miers Valley Photo by M.Becker UW MV Miers Valley Beacon Valley BP Photo by Nita Smith BV UW C/N LIMA Miers Valley, Beacon Valley.

14 Highly different inter-valley microbial communities

15 Conversion in the predicted functional capabilities

16 amoa gene copies g-1 soil antagonic dominances of AOA and AOB in the different Dry Valleys analyzed 1.4 1,4E+06 x ,2E+06 x 10 6 AOA AOB 1.0 1,0E+06 x ,0E+05 x ,0E+05 x ,0E+05 x ,0E+05 x ,0E+00 x 00 Upper Wright Valley Beacon Valley Battleship Promontory Miers Valley

17 Perfect model for investigating the physicochemical drivers of microbial diversity and there functions. How basic microbial functional capabilities like the nitrogen pathways are maintained in extreme ecosystems Relevance of nitrogen biogeochemistry and the microbial communities that mediate N transformations in extreme Antarctica environments Photo by Nita Smith McMurdo Dry Valleys of Victoria Land in Antarctica

18 N circulation and transfer from N reach near shore locations to N limited surrounding terrestrial habitats. Novel organisms and aspects of the ecology of microbial communities that mediate N transformation in natural environments. Relevance of nitrogen biogeochemistry and the microbial communities that mediate N transformations in extreme Polar environments.

19 Antarctic Circumnavigation Expedition (ACE) ACE is the first project of the Swiss Polar Institute

20 Extreme Environments - Arctic Understand the ice associated ecosystem and model future changes Full annual cycle from the winter freeze-up until the summer melt

21 Extreme Environments - Next Arctic campaign Mapping both physical and biological time series data to obtain a good understanding of ecosystem status and how systems respond to natural and human-based threats. Extreme N microbial Ecology

22 Our team Nuno Hugo Marisa Adriana João Paula Mafalda Joana Maria Catarina António

23 Acknowledgements Samantha Joye James Hollibaugh William Wiebe Alison Buchan Alyson Santoro Mark Stevens Craig Cary Charles Lee Ronald Kiene Pedro Duarte Trelita de Sousa João Canário Marisa Almeida Ana Paula Mucha Sandra Ramos Fátima Carvalho Teresa Borges Newton Gomes Paula Salgado Maria Monteiro Tatiana Necrasov Ana Machado Catarina Teixeira Hugo Ribeiro