[Frontiers in Microbiology] On the north shore of Great Salt Lake, Utah, USA, naturally occurring tar seeps at Rozel Point provide an opportunity to study a petroleum-rich environment adjacent to a hypersaline desert ecosystem.
Currently, this terminal lake is shrinking, and the Rozel tar spreads along the surface of the dry lakebed, forming seeps that are numerous and variable in size. These seeps result from high molecular weight hydrocarbons migrating up through cracks and fissures along faulted basalt and limestone.
Our gas analysis in the seeps revealed emissions of methane and carbon dioxide, suggesting microbial activities such as petroleum degradation and methanogenesis. To probe the microbial diversity, we collected Rozel petroleum samples from three distinctive seeps and extracted DNA then probed the taxonomic diversity with specific primers (16S rRNA genes of bacteria and archaea; 18S rRNA genes of eukaryotes; Internal Transcribed Spacers 1 and 2 for fungi).
Sequencing and a phylogenetic analysis demonstrated a robust microbial community in the tar including halophilic species originating from the nearby lake water and sediment as well as species that may degrade the petroleum. However, most of the bacterial signals were indicative of animal-related microbiota, likely introduced by the tar-entrapped fauna or from the surrounding ranchland.
A large portion of the fungal biosignatures were related to plant-associated species from the local steppe. Taken together, the Rozel tar seeps capture a unique snapshot of the biology in the area, which may be a compelling rationale for studying tar seeps on Earth as biosignature traps. Also, we share astrobiology insights for considering potential life on other space bodies: this hydrocarbon reservoir may serve as an analog for studies of similar biosignature-collecting asphalt seeps.
Entrapment Seep emerges and forms a deep puddle of sticky tar which can entrap animals of all sizes (Kornhauser et al., 2020) (white scale bar is 1 m). The top right panel shows a decaying pelican, which we monitored with a trail camera. According to our time lapse recordings, the coyote (whose carcass is beside the pelican in this photograph) came to scavenge the bird, but sat down to rest and got stuck in the tar (white scale bar is 1 m). The middle right panel shows a mouse (white scale bar is 10 cm). According to our trail cameras, we have frequently seen mice running across the cool tar at night when it is less viscous; this one was likely entrapped when the temperatures were higher. The bottom photo shows small flies, likely brine or alkali flies common to Great Salt Lake (white scale bar is 1 cm). The animal life would add to the microbiome of this seep. — Frontiers in Microbiology
- Biosignature reservoirs in the Rozel Point tar seeps at Great Salt Lake, Utah, Frontiers in Microbiology via PubMed
- Biosignature reservoirs in the Rozel Point tar seeps at Great Salt Lake, Utah, Frontiers in Microbiology
Astrobiology,
