Baseline Assessment of Coral Community Structure in a Disturbed Nearshore Reef in Dinagat Islands, Philippines

Abstract

Chronic local disturbances increasingly shape nearshore coral reefs in the Philippines, yet many remain poorly documented, particularly in small island settings. This study provides baseline ecological documentation of coral community structure in a shallow nearshore reef in Barangay Bilabid, Basilisa, Dinagat Islands, with attention to patterns of diversity and dominance under sustained anthropogenic pressure. Coral assemblages were surveyed using a transect–quadrat method across three sampling stations, and community structure was assessed using density, frequency, dominance, and genus importance values. A total of 274 coral colonies representing ten genera across eight families were recorded. Genus-level diversity was consistently low across stations, with a pooled diversity index of 0.6848. However, dominance indices indicated shared dominance rather than monopolization by a single genus. Acropora exhibited the highest importance values across all stations, followed by Turbinaria and Porites, while no single genus overwhelmingly dominated the assemblage. These results describe a coral community characterized by reduced diversity but retained internal organization, consistent with ecological filtering in disturbed nearshore environments. Rather than advancing new analytical metrics, this study demonstrates how dominance-based indicators can complement diversity measures in baseline assessments of reef condition. The findings establish an ecological reference point for a previously undocumented reef system and provide context for future monitoring and management in data-poor nearshore coastal environments.