Barcodes bring ocean's bottom-dwellers to light

At murky depths greater than 2,000 meters, ocean floors teem with little explored life.

The size and remoteness of this underwater ecosystem, not to mention the difficulty of growing its fragile denizens outside their habitat, lend an air of mystery to the seemingly lost world of deep sea dwellers.

In a paper recently published in the PNAS journal, Béatrice Lecroq and Franck Lejzerowicz from the laboratory of Pr. Jan Pawlowski, and their collaborators, used the ultra-deep sequencing technology to target a 36 base pair fragment of ribosomal DNA as a genetic barcode to distinguish between species of benthic foraminiferans, common bottom-dwelling deep-sea protozoans.

This microbarcode helped classify nearly all of the more than 800 unique taxonomic entities into distinct orders, about half of them into separate families, and a few into individual species.

The barcoding data revealed that most of the foraminiferal species were of the soft-walled, single-chambered kind, thought to have evolved early.

That finding challenges the long-held view that the multi-chambered species dominate the foraminiferan community.

With further optimization of the technology and expansion of the reference database, ultra-deep sequencing could help speed deep sea research, according to the authors.