Ice-associated microalgae significantly contribute to primary production and biogeochemical cycling in polar regions. Their distribution, however, is highly variable due to strong physicochemical gradients. This study uses a field-deployable hyperspectral scanning and photogrammetric approach to map the microspatial distribution of phototrophic biomass in sea-ice cores at mm-scale resolution using chlorophyll *a* (Chl *a*) as a proxy. Novel spectral indices were developed and correlated with extracted Chl *a*, enabling quantitative Chl *a* mapping in mg m⁻² at high resolution. This approach represents a significant advancement in characterizing microspatial variation in ice-associated algae, highlighting the potential of hyperspectral imaging for high-resolution monitoring of under-ice biophysical systems.

Emiliano Cimoli, Vanessa Lucieer, Klaus M. Meiners, Arjun Chennu, Katerina Castrisios, Ken G. Ryan, Lars Chresten Lund-Hansen, Andrew Martin, Fraser Kennedy, Arko Lucieer