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| Abstract Submission No. | ABS-2022-07-0176 |
| Title of Abstract | Light stress induced DMS(P) production in Skeletonema costatum: An experimental approach and field observation |
| Authors | Bhagyashri R. Naik*, Mangesh Gauns, Damodar Shenoy, Sujata Nilajkar, Hema Naik |
| Organisation | CSIR-National Institute of Oceanography |
| Address | Tisk- Usgao, Goa Ponda, Goa, India Pincode: 403406 Mobile: 9923378725 E-mail: shreenaik09@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | Dimethylsulphide (DMS) is a dominant anti-green house biogenic sulphur gas produced from its precursor dimethylsulphoniopropionate (DMSP); which is in turn produced primarily by marine phytoplankton. Skeletonema costatum, a cosmopolitan diatom species, is known to contribute ~1% to the total phytoplankton community in coastal waters of the eastern Arabian Sea. A non-axenic culture of S. costatum maintained in laboratory condition (25oC and at 1000 Lux; 12 hour photoperiod) was studied to comprehend the effects of different growth stages and light stress on DMSP and DMS production. The concentration of DMSP and DMS varied significantly at different growth stages of the culture experiment, with high release during the stationary growth phase. The S. costatum culture on average produced 1479±135.2 nM of DMSPt and 20.1±24.1 nM of DMS concentration. The intracellular DMSP concentration (normalized to cell volume) attained a maximum (483.1 µmol S cm-3) during the stationary phase (average: 148.5 µmol S cm-3) indicating more contribution from mature cells compared to younger/ smaller cells. Likewise, the exposure of culture to light (at 1000 Lux) after the 12 hour dark phase was found to cause a stress on the cells invariably leading to the elevated levels of DMS (~ 9 fold) in the experimental culture flasks. This observations corroborated findings of time-series experiment carried out at the open ocean station in the Arabian Sea (ASTS; 17oN 68oE), recording high DMS concentrations on early mornings just after sunrise. Thus, our study specifies that in addition to different growth stages of S. costatum which produce variable concentrations of DMSP and DMS, it also gives new information on the influence of light stress on DMS production. This finding should be taken into consideration as it may have a bearing on DMS flux calculations and budgeting. |