Genetic barcoding for the identification of seagrass species along the Tanzanian coast

Abstract

Seagrasses are crucial to marine biodiversity in the Southwestern Indian Ocean (SWIO) where they are increasingly threatened by human activities and climate change. In Tanzania, some areas have lost up to 10 % of seagrass cover. The success of seagrass restoration efforts has been limited, partially because of inaccurate taxonomic identification and the selection of unsuitable species for specific habitats, which reduces restoration success and slows seagrass recovery. Thirteen species are currently recorded based on their morphology alone. To improve species identification and distribution mapping, this study combined traditional morphological assessments with DNA barcoding, amplifying a ~526 bp fragment of the rbcL gene in 41 seagrass samples collected along the Tanzanian coast. BLAST results identified eight distinct species: Cymodocea rotundata, Enhalus acoroides, Halophila ovalis, Halodule uninervis, Oceana serrulata, Syringodium isoetifolium, Thalassia hemprichii and Thalassodendron ciliatum. These findings enhance the understanding of seagrass biodiversity in Tanzania and offer a stronger foundation for selecting species for restoration. They also highlight the need for broader genetic surveys across the SWIO to resolve taxonomic uncertainties in seagrasses.