01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-06-0218 |
| Title of Abstract | Phytoplankton size class dynamics during bloom and non-bloom conditions in the Northeastern Arabian Sea using in situ and satellite observations |
| Authors | R Chandra Sekhar Naik*, Aneesh A Lotliker, Sudarsana Rao Pandi, Rupam Kalita, Sanjiba Kumar BaliarSingh |
| Organisation | INCOIS |
| Address | INDIAN NATIONAL CENTRE FOR OCEAN INFORMATION SERVICES, HYDERABD, Telangana, India Pincode: 500090 E-mail: rcs.naik-p@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | Phytoplankton size classes (PSCs) play a central role in surface carbon export to the deep ocean by influencing photosynthetic efficiency, particle sinking rates, and food web structure. However, knowledge of PSC dynamics during bloom and non-bloom periods in the northeastern Arabian Sea is limited. To address this, phytoplankton absorption (aph) characteristics were investigated using concurrent in situ bio-optical measurements and satellite-derived products during three research cruises (SS348, SS356, and SS383). The PSCs were classified using phytoplankton absorption (aph(443)) and Slope (S443⿿510). Out of 18 stations, three micro-phytoplankton dominated stations with chlorophyll-a ranged between 3 and 5 mg m⁻³, five nano-phytoplankton dominated stations with chlorophyll-a, 0.5 and 3 mg m⁻³, and ten pico-phytoplankton stations under oligotrophic conditions (<0.5 mg m⁻³ Chl-a). The slope-based approach accurately estimates micro-plankton bloom and slightly underestimates nano as pico phytoplankton, in this region. The validation results in situ aph(443) versus satellite VIIRS retrieved aph(443) showed a moderately strong correlation (R²=0.733, slope = 0.60, n = 18, RMSE of 0.0153 m⁻¹, Bias = 0.0056 m⁻¹, and MAPE of 52.9%), with underestimation most evident in bloom conditions. Comparison of Hirata-derived PSCs with a region-specific model developed here showed well agreement (R²=0.996), highlighting the reliability of absorption-based approaches in this region. Overall, results demonstrate that aph(443) and S443⿿510 are robust indicators for PSC retrievals, highlighting the compatibility of in situ and satellite observations for bloom monitoring and phytoplankton community assessments in the Arabian Sea. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Keywords: Phytoplankton absorption spectra; Phytoplankton size classes; VIIRS- Satellite data validation; North Eastern Arabian Sea |
| For Awards | yes |
| Date Of Birth | 17-04-1996 |
| ECSN Registration Number | IIOE2-ECSN-0144 |