Spatial patterns of barnacle diversity across ecoregions of the eastern coastal margin of Bangladesh

The eastern coastal margin of Bangladesh, encompassing the diverse marine provinces and ecoregions along the Bay of Bengal, represents a biologically rich and ecologically significant zone. This study investigates the diversity, distribution, and cluster analysis of barnacle species in ecoregions of the eastern coastal margin of Bangladesh, with a particular focus on the Cox’s Bazar and St. Martin Island regions. Field investigations were conducted at representative sites across major ecoregions (rocky headlands, sandy shores, mudflats/estuarine fringes, and mangrove margins) during low tide, and barnacle specimens were collected using appropriate tools depending on the substrate type. Taxonomic classification was based on the shell, opercular valves, arthropodal characters, cirri, and mouth parts. Diversity was assessed using Simpson’s index (1–D), Shannon–Wiener (H), dominance (D), and evenness (e^H/S). The study recorded a total of 20 barnacle species from 13 genera and 8 families in the study area. The Balanidae family had the most species reported, indicating their ecological adaptivity and diverse substrate preference. Regarding spatial distribution, the genera Amphibalanus, Chthamalus, and Balanus were predominant. The intertidal species Amphibalanus amphirite and Amphibalanus reticulatus were common in the high- and mid-intertidal rocky shores of the Cox’s Bazar ecoregion. In the St. Martin ecoregion, Chthamalus challengeri and Balanus cretanus were the most prominent species. Amphibalanus amphirite was the most dominant invasive species identified in the study area. With the maximum species richness (8 taxa), comparatively low dominance (0.19), and the highest values for the Simpson index (0.81) and Shannon index (1.86), Maheshkhali 01 appears to be the most diversified site, suggesting a diverse and well-balanced barnacle community. Patuartek 02 exhibits low richness and strong dominance, indicating site-specific environmental constraints. These results highlight the significance of site-specific environmental management for intertidal community conservation and advance our understanding of Bangladesh’s coastal biodiversity patterns. The Balanidae family is the most abundant species across the eastern coastal margin of Bangladesh. Maheshkhali holds the most diverse barnacle species, and Patuartek shows low richness among all the studied sites. Increasing number of invasive barnacle species in Inani, Patuertek, and St. Martin’s Island indicates that site-specific environmental management is crucial for the coastal habitat of the eastern coastal margin of Bangladesh.