Extant microbial communities in the partially desiccated Rincon de Parangueo maar crater lake in Mexico

Abstract

Rincon de Parangueo is a maar where a perennial lake was present until the 1980s. A conspicuous feature of the lake’s sediments is the presence of bioherms and organo-sedimentary deposits produced by microbial communities. The gradual lake desiccation during the last 40 years has produced dramatic environmental changes inside the maar basin, which resulted in the formation of a highly saline-alkaline system with extant microorganisms. In this paper we succinctly describe the geologic setting where the microbial communities have developed inside of the maar crater and the results obtained from high-throughput sequencing methods to characterize the microbial component (Bacteria, Eukarya and Archaea) in endolithic mats of calcareous sediments, and microbial mats and free-living microorganisms in the soda ponds. The studied sites displayed different microbial communities with a diverse number of phylotypes belonging to Bacteria and Eukarya, contrasting with a much less diverse component in Archaea. The sequences here detected were related to environmental sequences from sites with extreme life conditions such as high alkalinity (alkaliphiles), high salinity (halophiles) and high temperature (thermophiles). Moreover, our results indicate an important unexplored endemic microbial biodiversity in the vestiges of the former lake that need to be studied.

Mobile mud layer underneath the desiccated maar lake of Rincón de Parangueo and insights into its microbial fingerprints

“…The sediments, exposed exceptionally by the lake desiccation, display a simple concentric carbonate facies distribution in RP (Figure 1a) (Aranda-Gómez et al, 2017;Sánchez-Sánchez et al, 2019). The platform bench is a nearly flat or gently inclined plane with a sedimentary sequence characterized by the presence of abundant oncolites.…”

“…The central part of the maar crater Rincón de Parangueo (RP) hosts a near-surface sedimentary sequence deposited in a closed lacustrine system (Kienel et al, 2009;Aranda-Gómez et al, 2013;Cerca et al, 2015;Domínguez-Vázquez et al, 2019;Sánchez-Sánchez et al, 2019). Sedimentary processes within the lacustrine system were active until the 1980's decade when overexploitation of the regional aquifer initiated a gradual decline of the water level and triggered active land subsidence (Aranda-Gómez et al, 2013;.…”

“…Nowadays, most of the crater surface is characterized by a dry carbonate plain, and only small residual brine ponds are present in the depocenter of the crater. Brine ponds are fed either by meteoric water during the rainy season and/ or by a local perched aquifer inside the crater (Aranda-Gómez et al, 2013), and/or by hydraulic connection with the regional aquifer favored by the fragmentation of the host rock during the volcanic eruption (Aranda-Gómez et al, 2013;Cerca et al, 2015;Sánchez-Sánchez et al, 2019). Despite the intense lake desiccation in this semiarid region, groundwater remains an important water contributor and the water table is maintained 1.2 m below the dry sedimentary cover.…”

“…Paz et al (2020) suggested that the CH 4 emanating from the maar bottom has a biogenic origin. Through time the RP lacustrine system sustained the presence of microbial communities in an extreme environment (Levresse et al, 2014;Chacón et al, 2018;Sánchez-Sánchez et al, 2019;Ibarra-Sánchez et al, 2020). Sánchez-Sánchez et al (2019) characterized the microbial component (Bacteria, Eukarya, and Archaea) in endolithic mats of calcareous sediments, and microbial mats and free-living microorganisms in the soda ponds in the crater.…”

“…Through time the RP lacustrine system sustained the presence of microbial communities in an extreme environment (Levresse et al, 2014;Chacón et al, 2018;Sánchez-Sánchez et al, 2019;Ibarra-Sánchez et al, 2020). Sánchez-Sánchez et al (2019) characterized the microbial component (Bacteria, Eukarya, and Archaea) in endolithic mats of calcareous sediments, and microbial mats and free-living microorganisms in the soda ponds in the crater. The phylotypes identified were related to the extreme environmental physicochemical characteristics (e. g., alkalinity and salinity).…”