Unravelling pre-monsoon phytoplankton: pigment profiles and community structure in the western and central Bay of Bengal

Context The phytoplankton community structure remains unexplored in the central Bay of Bengal. Understanding this structure is crucial for comprehending marine ecosystem dynamics and potential nutrient limitations. Aims This study aimed to investigate the phytoplankton community structure in the western and central Bay of Bengal during the pre-monsoon period of 2019. The focus was on identifying major phytoplankton groups and understanding their distribution patterns. Methods High-performance liquid chromatography, CHEMTAX analysis and microscopy were employed to analyse phytoplankton pigments and community composition. Nutrient analysis provided insights into potential nutrient limitations influencing phytoplankton distribution. Key results Cyanobacteria and Prochlorococcus dominated the upper water column, whereas chlorophytes, prymnesiophytes, chrysophytes and cyanobacteria were prevalent in deeper waters. Low levels of dissolved inorganic nitrogen and phosphorus in the upper euphotic column suggested potential nutrient limitations. Conclusions The study delineated the distribution of major phytoplankton groups and highlighted the influence of nutrient availability on community structure. It underscores the importance of employing multiple analytical methods to comprehensively assess phytoplankton diversity. Implications Insights from this study have contributed to our understanding of marine ecosystems in the Bay of Bengal, providing a baseline for future research and management efforts aimed at conserving and sustaining these vital ecosystems.