01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-06-0119 |
| Title of Abstract | Towards understanding the paradox associated with the rise in algal blooms of Noctiluca sp in coastal and offshore waters of India |
| Authors | Rajdeep Roy*, Aneesh Lotliker , Chiranjivi Jayaram , S K Baliarsingh |
| Organisation | National Remote Sensing Centre, ISRO, Kolkata, 700163 |
| Address | RRSC, NRSC, ISRO office, Kolkata Kolkata, West Bengal, India Pincode: 700156 E-mail: rajdeep_roy@nrsc.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | The recent intensification in the harmful algal blooms of Noctiluca sp in and around Indian waters has gained global attention. India has a coastline of approximately 7516 km with rich ecological diversity. Our analysis suggests this increase is presumably linked to changes in the silicate cycle due to reduction in sediment load in major rivers presumably due to damming effect. We observed low silicate concentrations (< 2 µmol) during monsoon and non-monsson seasons in offshore waters. Further, a comparison of historical data of major estuaries with recent measurements also delineates a reduction in silicate concentrations at least by one order. This is in line with the earlier published silicate budget, which show a reduction of silicate input in Indian waters. Our analysis suggests this depleting scenario is presumably fuelling ecosystem change from silicate-dependent diatom populations to more opportunistic Noctiluca sp. However, the increase in offshore waters in the northern Arabian Sea could be more complex. It is presumably linked to the declining strength of winter mixing aided by global warming. Our observation suggests that the formation of shallow mixed layers in the open ocean is restricting silicate recharge from deeper layers, thereby collapsing the winter blooms resulting in fast transition from diatom-driven community structure to more opportunistic Noctiluca scintillans. Our analysis clearly captures the complex interplay of socio-economic growth and feedback response of marine ecosystems; however, their implication in the ocean carbon budget, Indian fisheries, and the tourism sector remains to be thoroughly evaluated. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Noctiluca scintillans; algal blooms; ecosystem; fisheries, Arabian Sea |
| For Awards | no |