POSTER SESSION 3
15:30–17:30, Wednesday, September 16
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1148 | POSTER 95
VERTICAL REDISTRIBUTION OF CHLOROPHYLL AND UNCERTAINTY IN PRIMARY PRODUCTIVITY ESTIMATES IN THE FRAM STRAIT UNDER CHANGING LIGHT REGIMES
Warming-driven changes in the global ocean increasingly influence the vertical distribution of chlorophyll, particularly in climatically sensitive regions such as the Fram Strait. This region functions as a key Arctic gateway where contrasting water masses interact, forming a dynamic frontal system. The Fram Strait is characterized by the convergence of cold, low-salinity Polar Water from the East Greenland Shelf (EGS) and warm, saline Atlantic Water transported by the West Spitsbergen Current (WSC), resulting in a well-defined frontal zone (FZ). These distinct hydrographic regimes exhibit contrasting optical properties, leading to variability in underwater light availability. Stratification within these water masses promotes the formation of subsurface chlorophyll maxima (SCM), typically located near the base of the euphotic zone (~30–40 m), where light and nutrient conditions are optimal for phytoplankton growth. Although SCM layers can contribute substantially to total primary production, they are not effectively captured by satellite observations, which are largely insensitive to depths below approximately 30 m, thereby introducing uncertainty in productivity estimates. To reduce this uncertainty, radiative transfer simulations (using HydroLight) are coupled with shifted Gaussian productivity models that parameterize vertical chlorophyll distributions by representing SCM depth, magnitude, and vertical spread. These approaches improve the estimation of subsurface production. Model results suggest that subsurface production may partially offset reductions in surface chlorophyll under moderate stratification and sufficient light penetration. However, stronger stratification, enhanced colored dissolved organic matter (CDOM) absorption, and deeper SCM positioning reduce photosynthetic efficiency, limiting this compensatory effect and increasing uncertainty in regional productivity assessments.
Midhun shah Hussain, Institute of Oceanology of Polish Academy of Sciences, [email protected], https://orcid.org/0000-0003-0019-1903
Piotr Kowalczuk, Institute of Oceanology Polish Academy of Sciences, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
