| Abstract Submission No. | ABS-1.3-0205 |
| Title of Abstract | Climate Change-Induced Changes in Productivity in a High Arctic Fjord on the West Spitsbergen Shelf: A Process Analogy with the Coastal Bay of Bengal |
| Authors | Teesha Mathew*, Subeesh M P, Divya David T, Vidya PJ, Nuncio Murukesh, Ahammed Shereef MS, Sourav Chatterjee |
| Organisation | National Centre for Polar and Ocean Research |
| Address | Prabhus Emarald Alto Dabolim, Vasco Da Gama, India Pincode: 403804 E-mail: tshaocean@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Rapid climate change is transforming the coastal and ocean processes of the High Arctic, profoundly influencing productivity and ecosystem functioning. The West Spitsbergen Shelf (WSS), located along the Atlantic gateway to the Arctic Ocean, is a climatically sensitive region where warm, saline Atlantic Water (AW) interacts with cold Arctic waters and glacial melt. Kongsfjorden, an open fjord on the WSS, exemplifies this interaction, where surface freshening from glacial discharge overlies intruding AW at depth, creating a sharp halocline and stable stratification that regulate biological productivity. This hydrographic configuration closely resembles conditions in the coastal Bay of Bengal (BoB) during the southwest monsoon, where large riverine freshwater input overlies warm, saline subsurface waters advected from the Arabian Sea. In both systems, freshwater-induced stratification limits vertical nutrient supply, but episodic wind or convective mixing events can break this barrier, triggering short-lived productivity enhancements. Using in-situ observations and an ecosystem (ROMS¿NPZD) model, we investigated how climate-driven ocean¿atmosphere interactions modulate productivity in Kongsfjorden. The year 2014 emerged as exceptionally warm, with chlorophyll concentrations exceeding 12 µg L⁻¹, far above the typical summer maxima of 2¿4 µg L⁻¹. While the early bloom in 2014 was linked to nutrient-rich AW advection, a remarkable late-summer/autumn bloom was sustained by convective mixing triggered by enhanced oceanic heat loss. The surface-intensified AW inflow warmed the upper layer, and concurrent atmospheric cooling increased the air¿sea temperature gradient, promoting vertical overturning that replenished nutrients despite low light levels. This process-based similarity between Kongsfjorden and the BoB highlights the universality of freshwater¿saltwater interactions and their control on productivity in stratified coastal systems. As Arctic warming intensifies glacial melt and Indian monsoon variability alters freshwater input, both regions are likely to experience amplified stratification¿mixing feedbacks with significant ecological consequences. |
| Keywords | Chlorophyll,Atlantic water, Surface warming, Sensible feat flux, Ocean heat loss, Convective mixing |