Dynamics of a Heterotrophic Dinoflagellate, Protoperidinium divergens, in the South-Eastern Coastal Waters of the Bay of Bengal

This research is the first attempt to present temporal distribution of heterotrophic dinoflagellate Protoperidinium divergens and their relationship with diatom and environmental factors in the Maheshkhali channel, south-east coast of the Bay of Bengal, Bangladesh. The initiation of higher abundances of P. divergens were observed in October and reached its peak in November when diatoms were the most abundant phytoplankton. Protoperidinium divergens preferred comparatively low temperature from 20-22°C and high concentration of phosphate-phosphorus from 31-37 µM. It had insignificant relationship with nitrate-nitrogen. Lower abundances of P. divergens were observed during pre-monsoon and monsoon due to lower abundances of diatom and higher water temperature (>23°C). Protoperidinium divergens, therefore, were mainly controlled by the availability of diatom abundance at comparatively lower temperature and higher concentration of phosphate-phosphorus. This research is important to estimate the potential trophic impact of P. divergens in the Maheshkhali channel.