Chlorophyll-$a$ Antarctic landfast sea ice: A first synthesis of historical ice core data

Klaus M. Meiners (1, 2) , Martin Vancoppenolle (3) , Gauthier Carnat (4) , G. Castellani (5) , Bruno Delille (6) , Daniel Delille (7) , Gerhard S. Dieckmann (5) , H. Flores (5) , François Fripiat (8) , M. Grotti (9) , B. Lange (5) , Delphine Lannuzel (10) , A. Martin (11) , A. Mcminn (10) , Daiki Nomura (12) , Ilka Peeken (5) , P. Rivaro (9) , K. Ryan (13) , Jacqueline Stefels (14) , K. M. Swadling (2) , D. Thomas (15) , Jean-Louis Tison (4) , Pier van Der Merwe (2) , Maria A. van Leeuwe (14) , C. Weldrick (11) , J. Yang (16)

1 AAD - Australian Antarctic Division
2 ACE-CRC - Antarctic Climate and Ecosystems Cooperative Research Centre
3 NEMO R&D - Nucleus for European Modeling of the Ocean
4 Laboratoire de Glaciologie [Bruxelles]
5 AWI - Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine
6 Unité d'Océanographie Chimique
7 OOB - Observatoire océanologique de Banyuls
8 Geology and mineralogy, section of Mineralogy and Petrography
9 UniGe - Università degli studi di Genova = University of Genoa
10 IMAS - Institute for Marine and Antarctic Studies [Hobart]
11 Institute for Marine and Antarctic Studies and Centre for Marine Socioecology
12 Faculty of Fisheries Sciences [Hakodate]
13 School of Biological Sciences [Wellington, New Zealand]
14 GELIFES - Groningen Institute for Evolutionary Life Sciences [Groningen]
15 School of Ocean Sciences [Menai Bridge]
16 KOPRI - Korea Polar Research Institute

Historical sea ice core chlorophyll-$a$(Chl$a$) data are used to describe the seasonal, regional, and vertical distribution of ice algal biomass in Antarctic land fast sea ice. The analyses are based on the AntarcticFast Ice Algae Chlorophyll-a data set, a compilation of currently available sea ice Chla data from land fast sea ice cores collected at circum-Antarctic nearshore locations between 1970 and 2015. Ice cores were typically sampled from thermodynamically grown first-year ice and have thin snow depths (mean = 0.052 ± 0.097 m). The data set comprises 888 ice cores, including 404 full vertical profile cores. Integrated ice algal Chla bio mass(range:<0.1–219.9 mg/m², median = 4.4 mg/m², interquartile range = 9.9 mg/m²) peaks in late spring and shows elevated levels in autumn. The seasonal Chla development is consistent with the current understanding of physical drivers of ice algal biomass, including the seasonal cycle of irradiance and surface temperatures driving landfast sea ice growth and melt. Landfast ice regions with reported platelet ice formation show maximum ice algal biomass. Ice algal communities in the lowermost third of the ice cores dominate integrated Chla concentrations during most of the year, but internal and surface communities are important, particularly in winter. Through comparison of biomass estimates based on different sea ice sampling strategies, that is, analysis of full cores versus bottom-ice section sampling, we identify biases in common sampling approaches and provide recommendations for future survey programs: for example, the need to sample fast ice over its entire thickness and to measure auxiliary physicochemical parameters.

Mots clés: chlorophyll‐<em>a</em>; Antarctica; ice algae; fast ice

Domaines: Géophysique [physics.geo-ph]

Klaus M. Meiners, Martin Vancoppenolle, Gauthier Carnat, G. Castellani, Bruno Delille, et al.. Chlorophyll-$a$ Antarctic landfast sea ice: A first synthesis of historical ice core data. Journal of Geophysical Research. Oceans, 2018, 123 (11), pp.8444-8459. ⟨10.1029/2018jc014245⟩. ⟨hal-02190717⟩