Article Seasonal Surges in Bacterial Diversity along the Coastal Waters of the Eastern Arabian Sea

Abstract

The upwelling phenomenon plays a vital role within marine ecosystems, transporting essential nutrients from the bottom to the surface and boosting biological productivity. However, the bacterial community structure in upwelling zones along Western coast of India (WCI) is under-studied. This research systematically examines bacterial diversity across three sea-sons—Pre-monsoon (PR), Monsoon (MN), and Post-monsoon (PM)—using next-generation se-quencing. Our findings show distinct spatial patterns of bacterial communities in the Arabian Sea and demonstrate that ecological variations influence bacterial distribution in this dynamic envi-ronment. During MN, the bacterial community was notably distinct and diverse than during PR and PM, despite their lower abundance in MN. Non-Metric MDS cluster analysis revealed a 78% similarity (at order level) between PR and PM, indicating MN supports unique bacterial diversi-ty. KEGG analysis showed significant seasonal variations in metabolic functions, with increased functional potential during MN. Additionally, Carbohydrate-Active enZymes (CAZymes) analy-sis revealed distinct seasonal profiles, among which the GH13 enzymes were the most prevalent glycoside hydrolases during MN; predominantly sucrose phosphorylase and glucosidase, known for breaking down glucan deposits derived from phytoplankton. The CAZymes profiles sup-ported taxonomic and KEGG pathway findings, reinforcing that microbial communities are sea-sonally distinct and functionally adapted to changing availability of nutrients.