13 Earth Life Sciences across the Cordillera

This session showcases interdisciplinary research that bridges geological sciences with allied fields including (but not limited to) genetics, ecology, biogeography, archaeology, informatics to emphasize innovative approaches to understand the interconnectedness of Earth systems.

Wednesday, 22 April 2026
1:30 PM - 5:30 PM
LMH, Fiesta Terrace Salon

Archaea, Rare Biosphere Taxa, and Metabolic Stratification in Carbonate-Forming Microbial Mats of the Cuatro Ciénegas Basin

Paper number: 13-2
Program: Technical Sessions
Time: 2:10 PM – 2:30 PM

Authors

Abstract

The Cuatro Ciénegas Basin (CCB), Mexico, represents a unique astrobiological laboratory, hosting extant stromatolites, microbialites, and microbial mats that serve as analogs of Precambrian carbonate-forming ecosystems. CCB ponds are characterized by extreme oligotrophy and strongly unbalanced nutrient stoichiometry, particularly severe phosphorus limitation.

This study addresses two central questions: (1) what functional roles do Archaea and low-abundance (“rare biosphere”) taxa play in sustaining mat ecosystems, and (2) how do complex microbial communities persist and remain productive under extreme nutrient limitation? We characterized the taxonomic diversity and inferred metabolic potential of stratified microbial mats and microbialites using high-throughput shotgun metagenomic sequencing.

We show that CCB microbialites harbor bacterial and archaeal communities that are taxonomically distinct from those of adjacent mats, consistent with differences in carbonate precipitation and fabric development. In hypersaline Pozas Rojas mats, surface layers are dominated by cyanobacteria and heterotrophic bacteria, whereas deeper layers are enriched in archaea, consistent with metabolic partitioning along depth-related nutrient, redox, and carbonate saturation gradients; fungal signatures are detected throughout the mat profile. Archaeal lineages contribute disproportionately to pathways linked to nitrogen and carbon cycling, suggesting active niche occupation rather than passive persistence.

Functional inferences indicate that extreme phosphorus limitation structures community assembly and favors metabolic strategies such as efficient nutrient recycling, alternative phosphorus utilization, and flexible coupling between autotrophy and heterotrophy. Together, these results link archaeal activity, rare biosphere dynamics, and nutrient limitation to carbonate-forming microbial ecosystems, offering insights into microbial controls on mineral fabrics in both modern and ancient environments.

 

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

doi: 10.1130/abs/2026CD-410976

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