Towards improved estimates of sea-ice algal biomass:experimental assessment of hyperspectral imaging cameras for under-ice studies

• Published in: Annals of Glaciology
• Main Authors: Cimoli, Emiliano, Lucieer, Arko, Meiners, Klaus M., Lund-Hansen, Lars Chresten, Kennedy, Fraser, Martin, Andrew, McMinn, Andrew, Lucieer, Vanessa
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: hyperspectral imaging; ice algae; ice tank; remote sensing; sea ice; under-ice environment; SPRING GROWTH; ARCTIC-OCEAN; GREENLAND; PHOTOSYNTHESIS; TRANSMISSION; FLUORESCENCE; SPECTROSCOPY; VARIABILITY; RADIATION; BLOOM; Arctic; Arctic Ocean; Greenland; Annals of Glaciology; Sea ice
• Online Access: https://pure.au.dk/portal/da/publications/towards-improved-estimates-of-seaice-algal-biomass(f2ed9a70-c14c-4477-84fc-b730c4ec3729).html; https://doi.org/10.1017/aog.2017.6; https://pure.au.dk/ws/files/121892893/towards_improved_estimates_of_seaice_algal_biomass_experimental_assessment_of_hyperspectral_imaging_cameras_for_underice_studies.pdf

Ice algae are a key component in polar marine food webs and have an active role in large-scale biogeochemical cycles. They remain extremely under-sampled due to the coarse nature of traditional point sampling methods compounded by the general logistical limitations of surveying in polar regions. This study provides a first assessment of hyperspectral imaging as an under-ice remote-sensing method to capture sea-ice algae biomass spatial variability at the ice/water interface. Ice-algal cultures were inoculated in a unique inverted sea-ice simulation tank at increasing concentrations over designated cylinder enclosures and sparsely across the ice/water interface. Hyperspectral images of the sea ice were acquired with a pushbroom sensor attaining 0.9 mm square pixel spatial resolution for three different spectral resolutions (1.7, 3.4, 6.7 nm). Image analysis revealed biomass distribution matching the inoculated chlorophyll a concentrations within each cylinder. While spectral resolutions >6 nm hindered biomass differentiation, 1.7 and 3.4 nm were able to resolve spatial variation in ice algal biomass implying a coherent sensor selection. The inverted ice tank provided a suitable sea-ice analogue platform for testing key parameters of the methodology. The results highlight the potential of hyperspectral imaging to capture sea-ice algal biomass variability at unprecedented scales in a non-invasive way.