Assessing macroorganisms biodiversity in the Bay of Biscay through environmental DNA.

Supervisor: Naiara Rodriguez-Ezpeleta (AZTI).
Due to global change, marine biodiversity is declining around the world, which calls for measures to ensure a sustainable use of the marine environment and its resources. Development of such measures requires biodiversity surveys, which are generally invasive and costly. Recent improvements in DNA sequencing have led to the discovery of new genetic tools for marine monitoring. Among the most promising ones is environmental DNA (eDNA), which has the potential of providing information about the macroorganisms inhabiting a certain environment without the need of catching or seeing them. In this study, we have assessed the potential of eDNA to ease marine macroorganism biodiversity surveys in the Bay of Biscay. For that aim, we have amplified and sequenced a region of the 12S ribosomal RNA gene and of the cytochrome oxidase subunit I (COI) from the eDNA extracted from 48 water samples collected across the Bay of Biscay, including different depths. The taxonomic assignment of the sequencing reads obtained allowed the detection of almost 100 animal species (fishes, sharks and birds) expected in the area. A comparison of the biodiversity estimated through eDNA and other methods such as fishing and sightings in the same locations, highlighted the potential of eDNA based marine biodiversity surveys. Yet, it also emphasized the need for additional studies to better understand the advantages and limitations of this method, especially regarding the primer used and the database construction.