Abstract:
Seagrass beds are one of the most important marine ecosystems, but they are facing critical threats worldwide.
Like other regions in the world, this fragile ecosystem is declining in Viet Nam. The seagrass distribution and
species diversity of some archipelagos and islands of the West Sea of Viet Nam are still poorly studied. In this
study, small scale seagrass beds from 30 sites were mapped, species diversity was also determined. Ground
surveys and SENTINEL-2 image analyses were applied to determine the distribution of seagrass meadows in the
region. Morphological examination was used to identify specimens. For the Halophila ovalis complex, a nuclear
genetic marker (ITS1–5.8S-ITS2) was applied. In addition, the consensus ITS2 secondary structure was also used
to check the genetic relationship among H. ovalis and closely related species including H. minor, H. major and
H. nipponica. The results indicate that the total area of seagrass in the West Sea of Viet Nam is updated with
7632 ha.