7-8 Microbial Persistence And Stratification In Oligotrophic Sediments Of Pozas Rojas, Cuatro Ciénegas Basin, Mexico

Session: Earth Life Sciences across the Cordillera (Posters)

Poster Booth No.: 14

Presenting Author:

Authors:

González-Sánchez, Antonio Olmedo¹, Ibarra Arzave, Georgina ², Paniagua-Vargas, Atzintli³, García-Oliva, Felipe⁴, Olmedo Alvarez, Gabriela⁵

(1) Dept. Genetic Engineering, Cinvestav, Irapuato, Gto., Mexico, (2) Instituto de investigaciones en Ecosistemas y Sustentabilidad,, UNAM, Morelia, Michoacan, Mexico, (3) Instituto de investigaciones en Ecosistemas y Sustentabilidad, UNAM, Morelia, Michoacan, Mexico, (4) Instituto de investigaciones en Ecosistemas y Sustentabilidad, UNAM, Morelia, Michoacan, Mexico, (5) Dept. Genetic Engineering, Cinvestav, Irapuato, Gto., Mexico,

Abstract:

Pozas Rojas is a freshwater system in the Cuatro Ciénegas Basin (CCB), Coahuila, Mexico, consisting of multiple shallow pools (pozas) interconnected with a deeper lagoon. The site is characterized by extreme geochemical conditions, including highly unbalanced nutrient stoichiometry and oligotrophy, which historically acted as strong environmental filters shaping microbial community structure. Pozas Rojas thus represents a natural experiment for studying microbial community reassembly following disturbance, providing a unique opportunity to disentangle the relative roles of environmental filtering and biotic interactions in shaping aquatic microbial diversity over short ecological timescales.

In this study, we obtained a 48-cm sediment core from a Poza Roja, which was segmented into 11 layers for for stratigraphic framework and metagenomic analysis. We identified a remarkably high relative abundance of Archaea (~45%), highlighting Pozas Rojas as a geomicrobiological hotspot where extreme geochemistry promotes microbial assemblages typically found in marine or subsurface environments. The most abundant archaeal-associated taxa belong to poorly characterized and environmentally specialized lineages, including uncultured groups, halophiles, sulfur-cycling, anaerobic, and phototrophic-associated clades, revealing a community strongly structured by geochemical constraints rather than by freshwater identity.

The prevalence of uncultured and extremophile-associated taxa challenges conventional freshwater paradigms and positions Pozas Rojas as a natural laboratory where microbial traits characteristic of marine, subsurface, and extreme environments converge.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

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