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| Abstract Submission No. | ABS-2022-06-0020 |
| Title of Abstract | First report on living coccolithophore community from the north-western shelf waters of India during SW monsoon |
| Authors | Mintu Chowdhury*, Haimanti Biswas, Diksha Sharma, Saumya Silori |
| Organisation | CSIR-National Institute of Oceanography, Goa |
| Address | Biological Oceanography Division, CSIR-National Institute of Oceanography Panjim, Goa, India Pincode: 403004 Mobile: 7506022427 E-mail: mintuchy90@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | Coccolithophores, the calcifying photosynthetic nanophytoplankton, constitute a significant part of the phytoplankton community from the Arabian Sea. However, there is no published report on coccolithophores from the Indian shelf waters. We present here the first baseline data on coccolithophore abundance and community composition from five stations from 17°⿿21° N along the north-western Indian shelf (200 m depth contour) during southwest monsoon (SSD-55; August-2018). For quantitative and qualitative analysis, coccolithophore samples were inspected under a JEOL-JSM IT300 Scanning Electron Microscope (SEM) at CSIR-NIO. The results revealed the occurrences of a total of 18 species from 10 genera of coccolithophore at 6 different depths. High abundances of coccolithophores and coccoliths were observed in the northernmost station and decreased southward. Spatial and vertical profiles exhibited significant variability in species abundance and diversity. Gephyrocapsa oceanica was the most dominant coccolithophore species found in this region especially in the top 20 m followed by Umbilicosphaera sibogae, Helicosphaera carteri and Calcidiscus leptoporus. The deeper waters were dominated by the deep-photic species Florisphaera profunda. In the southernmost station, species such as Michaelsarsia adriaticus and Calciosolenia murrayi contributed substantially along with G. oceanica. Our results are consistent with the existing literature from the other parts of the north Indian Ocean. Such variability in coccolithophore distribution was linked to water column stratification, mixed layer depth, light, and nutrient dynamics. Furthermore, phytoplankton pigment analysis also confirmed their predominant abundance over diatoms and dinoflagellates in this oligotrophic region. We conclude that coccolithophores are an important component of the phytoplankton community in this region and are likely to contribute significantly to carbon cycling and the food chain. |