Analysis of reef fish community structure as a basis for identifying potential OECM in the Kilwaru-Kiltay Area, East Seram, Indonesia

Reef fish communities are widely used as sensitive bioindicators of coral reef ecosystem condition and provide an ecological basis for area- based conservation planning, including Other Effective Area-based Conservation Measures, yet site-specific ecological evidence supporting OECM screening remains limited in many eastern Indonesian reef systems. This study assessed reef fish community structure at nine stations in the Kilwaru-Kiltay waters, East Seram, using a standardized Underwater Visual Census conducted in May-June 2023, with species-level identification based on direct underwater observations and standard identification guides. Community structure was evaluated using abundance metrics, ecological indices, and Principal Component Analysis at family and species levels. A total of 115 reef fish species were recorded, showing high species richness and pronounced spatial variation among stations. Pomacentridae consistently dominated most sites, while diversity, evenness, and dominance indices revealed clear site-specific differences in internal community organization rather than uniform ecological conditions. Multivariate ordination further highlighted distinct spatial differentiation in assemblage composition and functional group structure across stations. These results demonstrate that reef fish community structure provides a robust, site- specific ecological indicator for screening potential OECM areas and supports spatially informed conservation planning beyond formally protected areas in eastern Indonesia.