Seasonal dimethylsulfoniopropionate (DMSP) variability in Dona Paula bay

Data on temporal variations of total dimethylsulfoniopropionate (DMSP t) and the environmental factors that influence DMSP t concentrations are important in understanding the biogeochemical cycling of organic sulfur compounds. Annual and diurnal variations of DMSP t were investigated in relation to environmental variables at a fixed station in Dona Paula bay (west coast of India). DMSP concentrations were high in the day and low at night and ranged from 3.69 to 84 nM with a maximum at 17.00 h. The high concentrations of DMSP t during daytime closely followed that of Chl a concentrations. The DMSP utilizers averaged 0.8 ± 0.3 × 10 3 cells l −1 during night and 0.4 ± 0.1 × 10 3 cells l −1 during the day. The diel variation of DMSP t was influenced more by biological variables than hydrographic parameters. In the year-round study, the concentrations ranged from 0.69 to 15.8 nM. It was fourfold higher during the southwest monsoon season (13.4 ± 2 nM) and threefold higher during the post-monsoon season (9.96 ± 5 nM) compared to the pre-monsoon season (3.1 ± 1 nM). DMSP t concentrations showed temporal variability, both during diurnal and annual studies. Diatoms were identified as producers of DMSP in Dona Paula bay. Dinoflagellates also contributed during the non-monsoon seasons. Another factor involved in the variability of DMSP t was DMSP utilizing bacteria, which ranged from 1 to 10% of the total heterotrophic count.