Doctorante : Claudia MATURANA (2019-2021)

Directeur (HDR): Pierre Galand (LECOB)
Co-directrice : Camila Fernandez (LOMIC)

Descriptif du sujet de thèse :
The southern Patagonia of Chile concentrates one of the largest reserves of fresh water in the world, which makes it a key region for the development of anthropogenic and productive activities. The coast of the Antarctic Peninsula is characterized by being very vulnerable to climate change and being an area of ​​high biodiversity and biomass production, presenting diverse and complex ecosystems that harbor rich marine communities controlled by local and regional oceanographic processes. For the sub-Antarctic and Antarctic zones, a decrease in ice cover is predicted, which will affect the marine and coastal systems, transforming its structure and altering the dominant species, their functioning and productivity levels. Regarding the structure of bacterial communities in bodies of waters of high latitudes with the entrance of fresh water from glaciers, different studies have reported presence of the three domains of life Bacteria, Archaea and Eukarya. Studies carried out in fjords of the southern Patagonia of Chile, suggest that the melting of glaciers would favour the development of microorganisms adapted to cold and low salinity during a scenario of high discharge, generating in this way changes in the structure of the normal microbial community and possible changes in the trophic web.

The Yendegaia fjord is characterized for being a low nutrient system and for presenting large aggregations of the shrimp Patagonia Munida gregaria. While the Pia Fjord is only 70 km away from the previous one, it has higher nutrient levels and absence of M. gregaria. The Marian Cove, located in the South Shetland Islands, has low temperature and surface salinity and a plume of dense inorganic matter is observed in the coastal areas as a result of the terrigenous contribution that occurs during periods of glacial water melting. Assuming that, climate change can affect all aspects of the biology of an organism, it is necessary to develop research focused on the effects of climate change on the structure of communities present in polar regions.

The present work contemplates the study of the structure of the bacterioplanctonic communities associated to the three fjords mentioned with emphasis in three aspects: (i) diversity, (ii) abundance and (iii) biogeochemical role.