16S rRNA gene profiling reveals distinct prokaryotic communities in sediment and seawater habitats of Pattani Bay, Thailand

Coastal habitats are rich in biodiversity that offer multifunctional ecosystem services. Understanding the roles of microbial dynamics and their distribution patterns is essential for ecosystem quality assessment, which, in turn, helps to decipher associated metagenomic insights. The study integrated 16S rRNA gene-targeted metagenomic data with environmental properties using sediment and seawater from selected coastal habitats (industrial, residential, protected) in Pattani Bay, Thailand. In the industrial-A habitat, both seawater and sediment had lowest mean observed OTUs (operational taxonomic units) of 428.5 and 318.0, and highest mean values were noted in residential sediment (1255.5) and industrial-B seawater (865.0). Despite sediment in the protected site having the second-highest mean OTUs (1240.0), seawater had the second-lowest by 345 OTUs. The dominant prokaryotes were Proteobacteria, Bacteroidota, Campylobacterota, Firmicutes, and Actinobacteriota, accounting for 82.8 % of the total community load. Sediments were enriched with Marinobacter, Sulfurimonas, Thiomicrorhabdus, Sulfurovum, and Rheinheimera genera, while seawaters were dominated by genera Pseudomonas, Shewanella, Bacillus, Rheinheimera, and Flavobacterium, respectively. Key sediment parameters having strong interplay with dominant taxa were soil texture, EC, and OM, and key seawater parameters included salinity, BOD₅, and PO₄^3-. PCA identified the influence of these environmental parameters on specific prokaryotic communities. High pollution load index of Industrial-A site may have contributed to lowest prokaryotic diversity, suggesting substantial influence of heavy metals. The current study revealed that prokaryotic composition was sensitive to unique environmental properties induced by local human-driven activities. Hence, all findings will contribute a strong theoretical basis for future coastal ecosystem quality assessments.