Copahue Geothermal System: A Volcanic Environment with Rich Extreme Prokaryotic Biodiversity

Abstract

The Copahue geothermal system is a natural extreme environment located at the northern end of the Cordillera de los Andes in Neuquén province in Argentina. The geochemistry and consequently the biodiversity of the area are dominated by the activity of the Copahue volcano. The main characteristic of Copahue is the extreme acidity of its aquatic environments; ponds and hot springs of moderate and high temperature as well as Río Agrio. In spite of being an apparently hostile location, the prokaryotic biodiversity detected by molecular ecology techniques as well as cultivation shows a rich and diverse environment dominated by acidophilic, sulphur oxidising bacteria or archaea, depending on the conditions of the particular niche studied. In microbial biofilms, found in the borders of the ponds where thermal activity is less intense, the species found are completely different, with a high presence of cyanobacteria and other photosynthetic species. Our results, collected during more than 10 years of work in Copahue, have enabled us to outline geomicrobiological models for the different environments found in the ponds and Río Agrio. Besides, Copahue seems to be the habitat of novel, not yet characterised autochthonous species, especially in the domain Archaea.

Untapped microbial composition along a horizontal oxygen gradient in a Costa Rican volcanic influenced acid rock drainage system

“…For example, in Río Tinto ARD system the [Fe]/[SO 4 2- ] molar ratio is 0.58 at the origin and only decreases to 0.29 downstream as expected from the 0.5 ratio from oxidation of pyrite FeS 2 ; however, in San Cayetano stream, we measure far lower ratios between 0.07 at the origin and 0.07-0.12 downstream. Our ratios compare well to the 0.15 and 0.06 ratios at Copahue Volcano’s (Urbieta et al . 2015).…”

“…On the other hand, the extreme acidity environments produced by discharge of the products of volcanic or hydrothermal activity ( e.g . H 2 S oxidation or SO 2 reaction with water) into water bodies like lakes and rivers, share most of their natural composition with that of ARD sites and are of interest because they can be unequivocally assigned to natural causes (Urbieta et al . 2015, Arce-Rodríguez et al .…”

Molecular Systematics of the Genus Acidithiobacillus: Insights into the Phylogenetic Structure and Diversification of the Taxon

“…Notably, none of the strains in our collection was affiliated with the 1B, 1C, or 1D subclades, which are mostly Asiatic or American in origin, and seem to be considerably less common than subclade 1A strains. Strains from the rare subclades that can be traced to natural environments seem to be associated to sulfidic caves (Jones et al, 2016) or geothermal sites (Urbieta et al, 2015). Strains from these subclades are as much as 3.7–5.2% divergent with respect to the type strain of A. caldus (ATCC 51756) at the level of the 16S rRNA gene, indicating that they comprise distinct species or even distinct genera.…”

A Deeper Look into the Biodiversity of the Extremely Acidic Copahue volcano-Río Agrio System in Neuquén, Argentina

“…After emerging from the Caviahue lake, the river, now called Lower Rio Agrio (LRA), is wider, has a larger flow, and is less acidic. Such changes, especially the pH increase, produce abundant precipitation of ferric minerals, which gives the red-orange color characteristic of the place [15]. This portion of Río Agrio is represented by a sample collected at a great waterfall called Salto del Agrio (SA) ( Figure 1F).…”