01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-06-0188 |
| Title of Abstract | Linking cyclone induced physical forcing to sources of POM and phytoplankton community shifts in the Arabian sea |
| Authors | D.N.Rao*, Aneesh Lotiker, E. Pattabhi Rama Rao, S. Shiva Prasad |
| Organisation | INDIAN NATIONAL CENTRE FOR OCEAN INFORMATION SERVICES |
| Address | INCOIS INDIAN NATIONAL CENTRE FOR OCEAN INFORMATION SERVICE, HYDERABAD, TELANGANA HYDERABAD, TELANGANA, India Pincode: 500090 E-mail: nr.darapu-p@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | The influence of Cyclone Biparjoy (June 2023) on particulate organic matter (POM) and its isotopic signatures (δ¹³C, δ¹⁵N) was investigated along the EKAMSAT pilot track (11.69°S-12.53°N; 66.59°W-67.87°E) in the Arabian Sea. The cyclone-induced high wind speeds, strong wind stress curl, and surface cooling enhanced upwelling of nutrient-rich subsurface waters, resulting in elevated chlorophyll-a (Chl-a) concentrations and a diatom-dominated bloom were observed. Mixed layer depth (MLD) was shallower in the cyclone region (~38 m) and deeper in the warm pool (~65 m). The C: N molar ratios (6.42±2.7) close to the canonical Redfield ratio (6.63), indicating predominantly in-situ production in Cyclone zone. POC concentrations were (higher 7.31±3.77 µM in the cyclonic area) (lower 5.22±1.79 µM in warm pool) revealed noticeable difference. In the cyclone zone, higher δ¹³CPOC (⿿22.8±1.25⿰) and δ¹⁵NPN (6.05±1.48⿰) values corresponded to a microplankton dominated community (66-98% of phytoplankton biomass) in the mixed layer, whereas the warm pool showed lower δ¹³CPOC (⿿25.11±1.66⿰) and δ¹⁵NPN (4.88±1.22⿰) values associated with pico¬plankton dominance (67-77%). Nanoplankton contributed 18-22.2% in the cyclone zone and 7.5-20% in the warm pool. In the cyclone impacted region, deep nitrate inputs high production, while δ¹⁵NPN > 7⿰ in POM between 75-200 m depth indicated the utilization of denitrified nitrogen. The PN isotopic signatures suggest source of nitrogen is lateral advected subsurface nutrients from the western arabian sea. This significant impact of cyclone on POM, changes the export flux pathways in the eastern Arabian sea. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Arabian sea, Biparjoy cyclone, Particulate organic matter, nutrients, phytoplankton |
| For Awards | yes |
| Date Of Birth | 11-02-1992 |
| ECSN Registration Number | IIOE2-ECSN-0128 |