Geoscientists probe geochemistry, microbial diversity of Peruvian hot springs

South America's Andes Mountains, the world's longest mountain range and home to some of the planet's highest peaks, feature hundreds of hot springs. Driven by plate tectonics and fueled by hot rock and fluids, their thermal discharges vary widely in geochemistry and microbial diversity.

"These results tell us tectonics matter when it comes microbial community make-up, but little research has been conducted around the world to demonstrate this"

Utah State University geoscientists and their colleagues examined hot spring systems in the southern Andes in Peru and discovered that microbial community composition is distinctly different in two tectonic settings. Dennis Newell and Heather Upin report the findings in Nature Communications: Earth & Environment. The research is supported by the U.S. National Science Foundation.

"We know tectonic processes control hot spring temperature and geochemistry, yet how this, in turn, shapes microbial community composition is poorly understood," says Newell.

The scientists collected geochemical and 16S ribosomal RNA gene sequencing data from hot springs in regions with contrasting styles of subduction — flat-slab and back-arc — and noted similarities in pH but found differences in geochemistry and microbiology.

"Flat-slab hot springs were chemically heterogeneous, had modest surface temperatures and were dominated by members of the metabolically diverse phylum Proteobacteria," Newell says.

In contrast, the back-arc hot springs were more geochemically homogenous, had hotter water, exhibited high concentrations of dissolved metals and gases, and were home to heat-loving archaeal and bacterial organisms.

"These results tell us tectonics matter when it comes microbial community make-up, but little research has been conducted around the world to demonstrate this," Newell says.

Further investigation, he says, with efficient genomic research, at sites around the globe could reveal how microbes have evolved in tectonically diverse environments.

"This research reinforces the idea that 'geology matters' when it comes to the microbial diversity of hot springs," says Stephen Harlan, a program director in NSF's Division of Earth Sciences. "It reveals that the large-scale tectonic processes operating at plate boundaries not only influence the geochemistry and temperatures of thermal fluids but also control how microbial life adapts to these environments."