Antarctic slush-ice algal accumulation not quantified through conventional satellite imagery: Beware the ice of March
J. L. Lieser1, M. A. J. Curran1,2, A. R. Bowie1,3, A. T. Davidson2, S. J. Doust2, A. D. Fraser1,4, B. K. Galton-Fenzi1,2, R. A. Massom1,2, K. M. Meiners1,2, J. Melbourne-Thomas1,2, P. A. Reid5, P. G. Strutton3,6, T. R. Vance1, M. Vancoppenolle7, K. J. Westwood1,2, and S. W. Wright1,21Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, 7001 Hobart, Australia 2Australian Antarctic Division, Channel Highway, 7050 Kingston, Tasmania, Australia 3Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, 7001 Hobart, Tasmania, Australia 4Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, 060-0819, Japan 5Bureau of Meteorology (CAWCR), G.P.O. Box 727, 7001 Hobart, Tasmania, Australia 6Australian Research Council Centre of Excellence for Climate System Science, University of Tasmania, 7001 Hobart, Tasmania, Australia 7Laboratoire d'Océanographie et du Climat (Expérimentations et Approches Numériques), L'OCÉAN – UMR7159 CNRS/IRD/UPMC/MNHN, IPSL Bote 100, 4 Place Jussieu, 75252 Paris CEDEX 05, France
Received: 17 Sep 2015 – Accepted for review: 27 Oct 2015 – Discussion started: 11 Nov 2015
Abstract. Our current knowledge of broad-scale patterns of primary production in the Southern Ocean is derived from satellite ocean-colour estimates of chlorophyll a (Chl a) in the open ocean, typically in spring-summer. Here, we provide evidence that large-scale intra-ice phytoplankton surface aggregation occur off the coast of Antarctica during austral autumn, and that these "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) conventional ocean-colour data, and (iii) direct sampling from a research vessel, to identify and characterise a large-scale intra-ice algal occurrence off the coast of East Antarctica in early autumn (March) 2012. We also present evidence of these autumn "blooms" in other regions (for example, Princess Astrid Coast in 2012) and other years (for example, Terra Nova Bay in 2015) implying regular and widespread occurrence of these phenomena. The occurrence of such undetected algal accumulations implies that the magnitude of primary production in the Southern Ocean is currently underestimated.
Lieser, J. L., Curran, M. A. J., Bowie, A. R., Davidson, A. T., Doust, S. J., Fraser, A. D., Galton-Fenzi, B. K., Massom, R. A., Meiners, K. M., Melbourne-Thomas, J., Reid, P. A., Strutton, P. G., Vance, T. R., Vancoppenolle, M., Westwood, K. J., and Wright, S. W.: Antarctic slush-ice algal accumulation not quantified through conventional satellite imagery: Beware the ice of March, The Cryosphere Discuss., 9, 6187-6222, doi:10.5194/tcd-9-6187-2015, 2015.