Spatial patterns of benthic foraminiferal diversity in relation to sediment type across contrasting coastal environments of Bangladesh

Understanding the relationship between foraminifera and sediment textures is essential for assessing environmental variability in dynamic coastal and marginal marine settings. This study aims to elucidate the influence of sediment texture on composition and distribution of foraminiferal assemblages along the Bay of Bengal coast of Bangladesh. A total of 34 sediment samples were obtained along the land-sea transect at three environmentally contrasting areas: Cox’s Bazar, Kuakata, and the Sundarbans, and analyzed for foraminifera, ecological indices, and granulometric characteristics. At the Sundarbans, fine sediments and low species diversity predominate. Kuakata was characterized by a mix of coarse and fine sediments and greater species diversity. In contrast, Cox’s Bazar consists primarily fine to medium sand with the highest foraminiferal species diversity among the three areas. Statistical analyses (Spearman’s Rank Correlation and Canonical Correspondence Analysis) revealed strong associations between sediment texture and foraminiferal assemblages, demonstrating clear substrate preferences. Two-way PERMANOVA further confirmed that sediment category plays a significant and geographically consistent role in driving foraminiferal assemblage composition across all three coastal environments. Previously recognized stress-tolerant taxa show dominance mainly in the Sundarbans, suggests preference for fine-grained, low-energy environments. Overall, the results demonstrate that the abundance and distribution of foraminifera are largely controlled by sediment textures and hydrodynamic conditions, highlighting their utility in environmental assessment, and interpretating coastal ecosystem responses to natural and anthropogenic forcing.