Mapping the in situ microspatial distribution of ice algal biomass through hyperspectral imaging of sea-ice cores
Cimoli, E.; Lucieer, V.; Meiners, K.M.; Chennu, A.; Castrisios, K.; Ryan, K.G.; Lund-Hansen, L.C.; Martin, A.; Kennedy, F.; Lucieer, A. (2020). Mapping the in situ microspatial distribution of ice algal biomass through hyperspectral imaging of sea-ice cores. NPG Scientific Reports 10(1). https://dx.doi.org/10.1038/s41598-020-79084-6
In: Scientific Reports (Nature Publishing Group). Nature Publishing Group: London. ISSN 2045-2322; e-ISSN 2045-2322, more
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| Authors | | Top |
- Cimoli, E.
- Lucieer, V.
- Meiners, K.M.
- Chennu, A.
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- Castrisios, K.
- Ryan, K.G.
- Lund-Hansen, L.C.
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- Martin, A.
- Kennedy, F.
- Lucieer, A.
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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. |
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