If well traditonally this chemical polluants had been attribued to the anthropic contamination from the mines and mine waste lixiviates, now it is clear that this extreme environnement is at least six million years old, enough time to allow the evolution of a surprising rich microbiota.
These conditions are not just the factors conditioning the life of extremophile microbes but direct consequence of its action: the sulphuric acid produced by aerobic chemotrophic bacteria that oxidize the pyrite.
This is why Rio Tinto it is a key natural lab to study the life in this conditions and has raised a major interest as an Earth's analogue of the hypothetical life in Mars, being, both the river and the metallic sulfur rocks of the zone a main subject of international research projects in astrobiology like the M.A.R.T.E. leaded by the NASA and the Astrobiology Center in Spain.
Last week I had the opportunity to visit the zone with a researcher during a Geology Symposium and I took some samples, now a bit degraded after some days in bottles.
1. Euglena mutabilis, one of the most common eukaryotes that tolerate this conditions. The lack of flagellum is very usual. Short stacks.
2. Euglena mutabilis single shot of an active specimen
3. It seems a decaying Euglena, but I'm not sure. Short stack.
4. Mineral precipitate crust formed at the surface of small ponds. It may mainly formed by jarosite, an Iron sulphate that needs water and acid pH to form and has been identified in Mars. Short stack
5. Bacterial mucose filament with mineral particules
6. Unknown form, not sure if it is a pollen grain or a true water inhabitant
All pictures with DIC, Leitz 40X NPL fluotar, about 100X on 7D sensor, heavily cropped
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