Antarctic slush-ice algal accumulation not quantified through conventional satellite imagery: beware the ice of March

• Main Authors: Lieser, JL, Curran, MAJ, Bowie, AR, Davidson, AT, Doust, SJ, Fraser, AD, Galton-Fenzi, BK, Massom, RA, Meiners, KM, Melbourne-Thomas, J, Reid, PA, Strutton, PG, Vance, TR, Vancoppenolle, M, Westwood, KJ, Wright, SW
• Format: Text
• Language: English
• Published: Copernicus GmbH 2015
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Physical Geography and Environmental Geoscience not elsewhere classified; Antarctic; Austral; East Antarctica; Southern Ocean; Terra Nova Bay; Antarc*; Antarctica; The Cryosphere; The Cryosphere Discussions
• Online Access: https://doi.org/10.5194/tcd-9-6187-2015; http://ecite.utas.edu.au/104455

Our current knowledge of broad-scale patterns of primary production in theSouthern Ocean is derived from satellite ocean-colour estimates ofchlorophyll a (Chl a ) in the open ocean, typically in spring-summer.Here, we provide evidence that large-scale intra-ice phytoplankton surfaceaggregation occur off the coast of Antarctica during austral autumn, and thatthese "blooms" are largely undetected in satellite ocean-colour time series(which mask the ice-covered ocean). We present an analysis of (i) true-colour(visible) satellite imagery in combination with (ii) conventionalocean-colour data, and (iii) direct sampling from a research vessel, toidentify and characterise a large-scale intra-ice algal occurrence off thecoast of East Antarctica in early autumn (March) 2012. We also presentevidence of these autumn "blooms" in other regions (for example, PrincessAstrid Coast in 2012) and other years (for example, Terra Nova Bay in 2015)implying regular and widespread occurrence of these phenomena. The occurrenceof such undetected algal accumulations implies that the magnitude of primaryproduction in the Southern Ocean is currently underestimated.