Fish population diversity assessment in the Eastern Province of Saudi Arabia, using environmental DNA (eDNA)

The marine ecological communities of Saudi Arabia’s waters along the eastern coast harbour diverse fish and prey communities that require comprehensive assessment for effective biodiversity management and conservation. The study aimed to increase our knowledge of fish and invertebrate diversity in the eastern coast of Saudi water by assessing diversity through DNA metabarcoding. The study examined whether there were differences in fish and invertebrate diversity among sampling locations along the eastern coast of the Saudi waters using eDNA, examining whether the Jubail Marine Wildlife Sanctuary exhibited greater species diversity than unprotected sites. This research identified prey taxa consumed by seven fish species landed from three sites (Dammam, Al Qatif, and Jubail) using DNA metabarcoding, to assess dietary overlap and species differences. The research also compared prey detected in the fish stomachs with taxa detected in water samples (eDNA), focusing on the most prevalent families and determining the length-weight relationships and growth patterns of focal fish species. The results showed that MiFish-U and COI primers detected 35 and 70 taxonomic families, respectively, across all samples. Fish stomach content analysis using DNA metabarcoding with multiple primers (MiFish-U, MiDeca, Crust16S, and Mollusc COI) identified 49, 38, 29, and 85 prey families, respectively. The comparison between focal fish stomach contents and water samples exhibited taxonomic correspondence in identified prey families including Sparidae, Carangidae, and Palaemonidae. The length-weight relationship analysis showed variation in fish length and weight patterns between species locations. This thesis demonstrates the value of integrating molecular and ecological tools to assess marine community diversity and to broaden understanding of fish and invertebrate diversity in Saudi Arabian waters along the eastern coast. These findings reveal complex trophic networks within the study area, provide a snapshot of species communities, and establish reference points for future research at local, regional, and global scales.