Multidimensional insights into the Persian Gulf and Gulf of Oman invertebrate diversity

Understanding biodiversity patterns in the Persian Gulf and the Gulf of Oman, two key ecoregions of the Western Indo-Pacific, is essential for effective conservation and management. In this study, we used available invertebrate occurrence records from the Ocean Biogeographic Information System (OBIS) and the Global Biodiversity Information Facility (GBIF) (Dataset A). Because many regional studies are not published in these databases, and to reduce sampling bias, we adopted two approaches: First, we integrated our unique database (Dataset B), which consisted of literature sources primarily from northern regions and field sampling data collected during extensive Iranian marine expeditions. This final dataset (A + B) included 61,894 records from 1,825 stations, covering depths from 0 to 1,250 m. Second, we employed ES50 and rarefaction techniques to further reduce expected sampling bias. Species diversity and composition (α, β, γ, Hʹ, Δ⁺) were evaluated across the study area. The Persian Gulf showed higher species diversity and composition compared to the Gulf of Oman, with diversity increasing from southern to northern coasts. Whittaker’s index indicated higher beta diversity in the Persian Gulf compared to the Gulf of Oman, with west–east turnover revealing distinct species compositions between the two basins and identifying eight sub-ecoregions. The funnel plot of Δ⁺ vs species richness revealed three coastal regions with high species diversity from various taxonomic groups (different orders, classes, or phyla), indicating high functional diversity, which enhances the ecosystem’s resilience to environmental stress. A multidimensional index that combines Shannon diversity, β diversity, and Δ⁺ has revealed offshore biodiversity hotspots and shown that β diversity and richness have a greater influence compared to Δ⁺ in biodiversity patterns from coastal to offshore areas. Our findings enhance understanding of biodiversity patterns in the region, despite challenges in data sharing and sampling, especially in the Gulf of Oman. They underscore the urgent need for conservation strategies for offshore ecosystems. We recommend that ROPME member states publish occurrence data in global repositories, adopt multi-index approaches, and encourage regional cooperation to improve information access and support sustainable marine conservation efforts.