18S rRNA gene amplicon sequencing of seawater eDNA and bulk DNA of panel scrapings from NEOM

Maritime traffic and coastal urbanisation significantly contribute to the introduction and proliferation of non-indigenous species (NIS). However, the lack of information might prevent effective monitoring of biodiversity trends in data-limited regions. This is particularly concerning in areas under demographic growth, where monitoring biofouling communities before development could offer crucial insights into the dynamics of NIS invasions. This study represents a baseline characterization of the biofouling communities in the northern Saudi Arabian Red Sea (NEOM region) prior to extensive urban, industrial, and commercial development. Samples were collected in November 2023 and February 2024 from seven sites within the region. At each site, three settlement structures, each with a PVC panel attached to a brick and a rope, were sampled after 3-months deployment. Each panel was analysed with photo quadrats (PhQd), examined to collect sessile macroinvertebrate specimens for further taxonomic identification using morphological and DNA barcoding analysis, and scraped for bulk DNA analyses using DNA metabarcoding. At each site and time, five seawater samples were also collected for environmental DNA (eDNA) analysis. The environmental characteristics of each site were obtained by deploying temperature data loggers and through a desk-based environmental risk assessment.