Glacial influence affect modularity in bacterial community structure in three deep Andean North- Patagonian lakes.

MODENUTTI, B.; MARTYNIUK, N.; BASTIDAS NAVARRO, M.; BALSEIRO, E.

Palmas de Mallorca

Congreso; ASLO Aquatic Sciences Meeting; 2023

ASLO

We analyze the bacteria community composition and the ecological processes structuring these communities in three deep mountain lakes that receive meltwater from the glaciers of Mount Tronador (North-Patagonia, Argentina). Lakes differ in their glacial connectivity and in their turbidity due to glacial particles. Lake Ventisquero Negro is a recently formed proglacial lake and it is still in contact with the glacier. Lakes Mascardi and Frías lost their glacial connectivity during the Pleistocene-Holocene transition. Total dissolved solid concentration has a significant contribution to the environmental gradient determining the segregation of the three lakes. The net relatedness index (NRI) showed that the bacterial community of lake Ventisquero Negro is determined by environmental filtering, while in the other lakes, species interaction would be a more important driver. The co-occurrence network analysis showed an increase in modularity and in the number of modules when comparing Lake Ventisquero Negro with the two large glacier-fed lakes suggesting an increase in heterogeneity. At the same time, the presence of modules with phototrophic bacteria (Cyanobium strains) in lakes Frías and Mascardi would reflect the increase of this functional photosynthetic association. Overall, our results showed that the reduction in ice masses in Patagonia will affect downstream large deep piedmont lakes losing the glacial influence in their bacterial communities.