- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-06-0049 |
| Title of Abstract | Impacts of continental aerosol on a natural phytoplankton community under variable CO2 levels from NE Arabian Sea |
| Authors | Diksha Sharma*, Haimanti Biswas, Saumya Silori, Mintu Chowdhury, Ashwini M, Ashwini Kumar, Debasmita Bandyopadhyay |
| Organisation | CSIR-National Institute of Oceanography |
| Address | CSIR-National Institute of Oceanography Dona Paula, Goa, India Pincode: 403004 Mobile: 8805985737 E-mail: dikshas0308@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | The Arabian Sea is a significant sink of atmospheric dust and satellite data-based model studies showed a close coupling between dust fall events and phytoplankton production suggesting its nutrient enrichment impact. The Arabian Sea is warming faster than any other oceanic basin and may lead to enhanced stratification and oligotrophy in the future. In this context, the significance of atmospheric dust-induced nutrient enrichment may increase and exert a considerable impact on phytoplankton growth and community composition. At the same time, the Arabian Sea is also a natural source of atmospheric CO2 and in the future, the projected increase in atmospheric CO2 level may further intensify the condition. However, how phytoplankton would respond to the combined enrichment of CO2 and atmospheric dust is not well known. We present here the results of a microcosm experiment [conducted onboard RV Sindhu Sadhana, on the natural phytoplankton community collected from the northeastern Arabian Sea (19° N; 73.69° E)] during the southwest (SW) monsoon (Aug 2018). The nutrient levels were quite low and two pCO2 levels were chosen (ambient CO2: A-CO2 470µatm; and high: H-CO2 970 µatm). The Atmospheric dust used for this experiment was collected (30th May 2018) from the west coast of India (Goa). Our results revealed that phytoplankton biomass was nearly unchanged in response to elevated CO supply; whereas, dust addition made a significant enhancement under both CO2 levels. Such growth-stimulating impacts can be attributed to mostly nitrogen and iron enrichment from the dust and are consistent with earlier literature. The dominating pennate diatoms Pseudo-nitzschia, Cylindrotheca closterium, and Nitzschia sp. were seemed to be well adapted to an H-CO2 condition. In contrast, a few centric diatoms like Dactyliosolen sp., and Guinardia sp. showed CO2-fertilisation impact. Almost all phytoplankton showed a growth stimulatory effect under aerosol enrichment, particularly diatom like Pseudo-nitzschia sp., C. closterium, Nitzschia sp., Guinardia sp., D. fragilissimus, and Leptocylindrus sp. Importantly, some phytoplankton genera exhibited reduced cell density at the elevated CO2 levels; however, recovered by aerosol addition. The concerning fact was to notice a few toxic producing diatoms under the elevated CO2 levels (with and without dust) and may be marked as potential bloom-forming species under future ocean scenarios. Some important ecological processes like grazing and trophic transfer can be considerably impacted by such a community shift. This is the first experimental study on this aspect and needs further investigation. |