Researchers at AZTI explored how they could use environmental DNA (eDNA) collected in the open ocean in order to gather more knowledge on deep sea fish.

Model of DNA strands. By Topshots (Adobe Stock)

When analyzing samples of seawater taken from the Bay of Biscay, down to a depth of  2000 meters, they detected the eDNA of 52 different fish species floating around as particles, where 25 of them were classified as deep sea fish. The scientists found that the deeper the samples were, the more deep sea fish DNA was present. Another pattern found was that the DNA abundance during day and night reflected the diel vertical migration (DVM) behavior of many mesopelagic fishes!  These findings are exciting because it shows that this method of DNA collection could be an efficient way to understand deep-sea fish ecology, diversity and species-specific DVM behavior!

Acess the full article here: Vertical stratification of environmental DNA in the open ocean captures ecological patterns and behavior of deep-sea fishes (Canals et al.) and read the abstract below!

Abstract: Establishing the foundations for a sustainable use of deep-sea resources relies on increasing knowledge on this inaccessible ecosystem, which is challenging with traditional methods. The analysis of environmental DNA (eDNA) emerges as an alternative, but it has been scarcely applied to deep-sea fish. Here, we have analyzed the fish eDNA contained in oceanic vertical profile samples (up to 2000 m depth) collected throughout the continental slope of the Bay of Biscay. We detected 52 different fish species, of which 25 were classified as deep-sea fish. We found an increase of deep-sea fish richness and abundance with depth, and that eDNA reflects day–night community patterns and species-specific vertical distributions that are consistent with the known diel migratory behavior of many mesopelagic fishes. These findings highlight the potential of eDNA to improve knowledge on the fish species inhabiting the dark ocean before this still pristine ecosystem is further exploited.