Program MARVEL : Marine Vertebrate eDNA Long-term monitoring, UAE

Arabian Gulf: The world's hottest sea

Marine organisms in the Arabian Gulf live under extreme and globally unique environmental conditions: surface temperatures exceeding 35 °C in summer, among the highest salinities of any open sea, and shallow depths. The impacts of local human activities are particularly pronounced, making this gulf an exceptional natural laboratory for studying marine biodiversity under environmental stress.

Background

This project aims to characterise the biodiversity of mobile marine vertebrate fauna — bony fish, cartilaginous fish, marine mammals… — in the coastal waters of the United Arab Emirates, using environmental DNA (eDNA) metabarcoding as a non-invasive monitoring tool.

Coastal zones are ecologically critical ecosystems — coral reefs, seagrass beds, mangroves — subject to increasing anthropogenic pressures: maritime traffic, marine pollution and habitat degradation. Mobile fauna is particularly difficult to sample with conventional methods (scientific fishing, hydroacoustics, visual surveys).

eDNA provides a powerful, non-invasive alternative: by filtering seawater following strictly controlled sampling protocols, it is possible to inventory the species whose DNA is present, without capturing or disturbing any organisms.

Methodological approach

Sampling is carried out at sea on small vessels, by filtering 30 litres of sub-surface seawater along linear transects at slow speed (2–5 knots). Samples are then analysed in the laboratory using a metabarcoding procedure that assigns each DNA molecule to its taxon of origin.

Environmental DNA — Analysis of a mixture of DNA molecules extracted directly from seawater, without prior isolation of organisms.
Target fauna — Bony fish, cartilaginous fish (sharks, rays) and marine mammals present in the coastal waters of Abu Dhabi.
Sites of interest — Marine protected areas, coral reefs, seagrass beds, port areas and heavily anthropised zones.
Expected results — Naturalistic inventories per site, biodiversity indices and spatial comparisons; temporal changes will be particularly monitored over the long term.

Scientific objectives

The project will produce biodiversity inventories enabling comparison of faunal assemblages between sites and across time periods, in order to assess the impact of human activities on mobile marine fauna in UAE waters. Additionally, the construction of a reference DNA barcode database of local species is envisaged to improve the taxonomic identification of eDNA sequences.