Foraminifera community assemblages from the southern Maldivian Archipelago: A helpful baseline for future environmental assessments

Foraminifera assemblages from seafloor deposits can serve as bioindicators for environmental conditions. Ideally, baseline catalogues of foraminifer communities nearest to a geographical location of interest are used to identify and compare findings. Such databases, however, do not exist for many geographic locations. This study examines the previously undocumented foraminiferal communities of three southern Maldives atolls and an island; Huvadhu, Addu, and Fuvahmulah covering 26 distinct sites. Sediment samples, collected during the Pristine Seas Program survey of these atolls, aimed to better understand the atolls' biodiversity, ecology and environmental health amid increasing anthropogenic pressures and climate change. A total of 320 species across 118 genera were identified. Results reveal distinct assemblage patterns influenced by substrate type, reef morphology, and depth. Assemblages were dominated by symbiont-bearing rotaliids and planktonic forams accompanied by diverse miliolids and diversity indices indicate overall high ecological stability. Huvadhu, with fewer species but higher dominance by stable, reef-associated taxa, suggests a pristine environment, while Fuvahmulah and Addu show signs of localized stress, likely due in part to tourism and development. Statistical analyses demonstrate significant community differences among atolls, with high heterogeneity within Addu reflecting varied habitat conditions, substrate types, and depth being the principal drivers of assemblage composition. Compared with the central and northern Maldives, the southern atolls exhibit greater species richness and evenness, suggesting more pristine reef environments. As tourism expands, baseline biodiversity assessments like this help in future ecological monitoring and provide new insights into biogeographic gradients and environmental stability within the Indian Ocean reef systems.