01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-02-0237 |
| Title of Abstract | Effects of upwelling-driven acidification and deoxygenation on the dissolved inorganic carbon system over the southeastern Arabian Sea shelf |
| Authors | Sudheesh V*, Gupta GVM |
| Organisation | Central University of Kerala, Kasaragod |
| Address | Central University of Kerala (CUK) Periye, Kerala, India Pincode: 671325 E-mail: sudhikeloth13@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Repeat measurements of inorganic carbon parameters for a year over two coastal transects (Kochi and Mangalore) from the southeastern Arabian Sea (SEAS) reveal significant acidification induced by the summer monsoon (June-September) upwelling that co-occurred with intense deoxygenation. High pH (oxygen) levels 8.096±0.073 (163±45.8 µM) during the pre-upwelling period dropped sharply to 7.857±0.038 (21.6±19.2 µM) when upwelled waters intruded onto the SEAS shelf. The inner shelf of Mangalore recorded anoxic/sulphidic conditions, while the same from Kochi remained hypoxic (17.47±6.5 µM). Despite this, the pH variation between these regions was minimal (7.834±0.044 and 7.861±0.034, respectively). Upwelling of acidic waters onto the continental shelves drastically affected the carbonate system; the calcite (ΩCa) and aragonite (ΩAr) saturations of bottom waters during upwelling (2.45±0.23 and 1.61±0.15) dropped to nearly half their pre-upwelling levels (4.54±0.71 and 3.02±0.48). ΩCa and ΩAr reached as low as 2.5 and 1.5 in the nearshore waters when pCO2 exceeded 1000 µatm under intense redox conditions, which lasted for about 15 days. The duration of such conditions increased with increasing depth, persisted for around three months at the outer shelf, albeit the SEAS shelves never fell below their threshold value (Ω=1). The co-existence of oxygen-deficient conditions with changes in carbonate saturation levels and buffering capacity during the summer monsoon has severe implications for ecosystem functioning. Being an essential metabolite, oxygen deficiency harms functional macrobenthic diversity. However, the effects of acidification on non-calcifying organisms in the SEAS remain unknown, as they both co-exist, making it challenging to separate their effects, necessitating further attention. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Upwelling, hypoxia, Inorganic carbon system, multiple stress, ecosystem impacts |
| For Awards | yes |
| Date Of Birth | 24-06-1989 |
| ECSN Registration Number | IIOE2-ECSN-029 |