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Abstract

Ice-associated microalgae make a significant seasonal contribution to primary production and biogeochemical cycling in polar regions. However, the distribution of algal cells is driven by strong physicochemical gradients which lead to a degree of microspatial variability in the microbial biomass that is significant, but difficult to quantify. We address this methodological gap by employing a field-deployable hyperspectral scanning and photogrammetric approach to study sea-ice cores. The optical set-up facilitated unsupervised mapping of the vertical and horizontal distribution of phototrophic biomass in sea-ice cores at mm-scale resolution (using chlorophyll a [Chl a] as proxy), and enabled the development of novel spectral indices to be tested against extracted Chl a (R2 ≤ 0.84). The modelled bio-optical relationships were applied to hyperspectral imagery captured both in situ (using an under-ice sliding platform) and ex situ (on the extracted cores) to quantitatively map Chl a in mg m−2 at high-resolution (≤ 2.4 mm). The optical quantification of Chl a on a per-pixel basis represents a step-change in characterising microspatial variation in the distribution of ice-associated algae. This study highlights the need to increase the resolution at which we monitor under-ice biophysical systems, and the emerging capability of hyperspectral imaging technologies to deliver on this research goal.

Item Type:	Article
Authors/Creators:	Cimoli, E and Lucieer, V and Meiners, KM and Chennu, A and Castrisios, K and Ryan, KG and Lund-Hansen, LC and Martin, A and Kennedy, F and Lucieer, A
Keywords:	hyperspectral, sea-ice
Journal or Publication Title:	Scientific Reports
Publisher:	Nature Publishing Group
ISSN:	2045-2322
DOI / ID Number:	10.1038/s41598-020-79084-6
Copyright Information:	Copyright 2020 The Authors Tis article is licensed under a Creative Commons Attribution 4.0 International License
Related URLs:	Google Scholar: Lucieer, V UTAS Profile: Lucieer, V Google Scholar: Martin, A UTAS Profile: Martin, A Google Scholar: Lucieer, A UTAS Profile: Lucieer, A
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