- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-04-0163 |
| Title of Abstract | Real-time assessment of phytoplankton photosynthetic activity using underway Fast repetition rate fluorometry (FRRf) |
| Authors | Jagadish S Patil*, V.V.S.S. Sarma |
| Organisation | CSIR-National Institute of Oceanography, Goa |
| Address | CSIR-National Institute of Oceanography, Dona Paula, Goa PANAJI, GOA, India Pincode: 403002 Mobile: 9420160997 E-mail: patilj@nio.org |
| Country | India |
| Presentation | Oral |
| Abstract | The distribution of phytoplankton is known to be heterogeneous with space and time; hence, vertical profiles of plankton provides only a snap-shot of spatial variability. In order to capture the heterogeneous distribution of planktonic constituents various efforts are being made to generate high-resolution data at spatial and temporal scale using modern automated through-flow systems (e.g., fluorometer). This study, for the first time, explores the in situ versions of fast repetition rate fluorometry (FRRf; FastOcean fluorometer, Chelsea Ltd.) to probe phytoplankton biomass and physiological status at high spatial and temporal resolution along the cruise track from Goa (India) to the northeastern Arabian Sea and back during February 2015. During the voyages we could able to detect several chlorophyll peaks with a notable massive green Noctiluca bloom. The variable fluorescence detected bloom between 20oN and 22oN, and the causative phytoplankton was diatoms (between 200N and 210N) and green Noctiluca (between 21oN and 22oN). Further photosynthetic efficiency (Fv/Fm) was relatively lower during the day than night time, and the photoinhibition could be one of the possible reasons for the former. For physiological assessment following scenarios low (<0.30), moderate (0.30⿿0.50) and high (0.51⿿0.65) levels of Fv/Fm suggesting stressed, transitional and growing conditions, respectively for phytoplankton were adapted. Fv/Fm was moderate and low to moderate in the bloom and non-bloom region respectively. The dominance of cells, which are either in growing stage (lag to exponential during bloom development) or in stationary to declining phase of the developed bloom or the prevalent of low-nutrient concentrations could be the potential reasons for moderate and low Fv/Fm respectively. Nevertheless, the recorded low to moderate night time Fv/Fm values were consistent with elsewhere in the world, suggesting that the phytoplankton community operates approximately half of maximum photosynthetic efficiency (Fv/Fm = 0.65) in this region as well. The presentation highlights the incorporation of such proposed high-resolution measurements (on phytoplankton biomass and photosynthetic activity) and the ways for data correction to generate robust data using ships of opportunity beneficial for ocean research. |