New Extremophiles: so many ocean bottom dwellers (Introduction)

by David Turell , Sunday, February 06, 2022, 15:09 (1021 days ago) @ David Turell

A review of current findings:

https://www.sciencealert.com/dna-shed-by-deep-sea-organisms-reveals-an-abyss-teeming-wi...

"Sweeping the ocean floor at hundreds of points throughout the world, researchers have revealed an astonishing diversity of microscopic life thriving in the deepest and darkest parts of our planet.

"The sediment collected at each spot was analyzed for environmental DNA (eDNA), which marine animals shed as they go about their lives. While sea creatures cast off some of that eDNA, among that material is also evidence of microbes and other tiny animals that make up the shadowy ecosystem at the bottom of the world.

***

"In the end, the researchers found most eukaryotic organisms living on the ocean floor are unknown to modern science. What's more, it looks as though the ocean's abyss is home to at least three times the diversity of microbial life as the waters above.

"It's the first time scientists have put together a consistent molecular dataset of the ocean realm on a such global scale, and while the meta-analysis isn't comprehensive, it's an impressive start.

"'We compared our deep-sea benthic DNA sequences to all reference sequences available for known eukaryotes," says geneticist Jan Pawlowski from the University of Geneva in Switzerland.

"'Our data indicates that nearly two-third[s] of this benthic diversity cannot be assigned to any known group, revealing a major gap in our knowledge of marine biodiversity."

***

"The current analysis mostly looked for smaller-sized organisms, like diatoms and dinoflagellates, and tiny animals, like worms and small molluscs. The diversity of plankton found matches other evidence suggesting the deep sea is also home to a diversity of larger animals.

"The tiniest creatures, however, are often the glue that holds food webs together. They are also critical regulators of the global climate, helping to bury carbon in the deep ocean. (my bold)

"'These deep-ocean sediment assemblages comprise not only taxa that are known to be important drivers of the biological carbon pump but also several taxonomic and functional groups that have been overlooked in what is arguably one of the most fundamental ecological processes of the world ocean," the authors write.

"'Together, our results highlight the [deep ocean sediment] as one of Earth's richest modern ecosystems and fossil archives.'" (my bold)

Comment: Again, an example of the diversity of life where I believe life started.