Response of phytoplankton dynamics to 19-year (1991–2009) climate trends in Potter Cove (Antarctica) ☆ Irene R. Schloss a, b, c, ⁎, Doris Abele d , Sébastien Moreau c , Serge Demers c , A.Valeria Bers d , Oscar González a , Gustavo A. Ferreyra c a Instituto Antártico Argentino, Cerrito 1248 C1010AAZ Ciudad Autónoma de Buenos Aires, Argentina b CONICET, Av. Rivadavia 1917, C1033AAJ, Ciudad de Buenos Aires, Argentina c Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310, Allée des Ursulines, Rimouski, Québec, Canada, G5L 3A1 d Alfred-Wegener-Institut für Polar- und Meeresforschung Am Handelshafen 12-Geb. E 27570, Bremerhaven,Germany abstract article info Article history: Received 15 July 2011 Received in revised form 4 October 2011 Accepted 7 October 2011 Available online 20 October 2011 Keywords: Coastal fjord-like system Antarctica Temperature Phytoplankton SAM Hydrography Particulate matter King George Island (KGI, Isla 25 de Mayo) is located within one of the most rapidly warming regions on Earth at the north-western tip of the Antarctic Peninsula. Since 1991 hydrographical characteristics and phyto- plankton dynamics were monitored at two stations in Potter Cove, a fjord-like environment on the south- eastern KGI coastline. Seawater temperature and salinity, total suspended particulate matter (TSPM) and chlorophyll-a (Chl-a, a proxy for phytoplankton biomass) concentrations were measured in summer and winter over a 19-year period, together with local air temperature. Mean air temperatures rose by 0.39 and 0.48 °C per decade in summer and winter, respectively. Positive anomalies characterized wind speeds during the decade between the mid '90 and the mid 2000 years, whereas negative anomalies were observed from 2004 onwards. Day of sea ice formation and retreat, based on satellite data, did not change, although total sea ice cover diminished during the studied period. Surface water temperature increased during summer (0.36 °C per decade), whereas no trend was observed in salinity. Summer Chl-a concentra- tions were around 1 mg m -3 Chl-a with no clear trend throughout the study period. TSPM increased in sur- face waters of the inner cove during the spring-summer months. The Southern Annular Mode (SAM) climate signal was apparent in the fluctuating interannual pattern of the hydrographic variables in the outer Potter Cove and bottom waters whereas surface hydrography was strongly governed by the local forcing of glacier melt. The results show that global trends have significant effects on local hydrographical and biological con- ditions in the coastal marine environments of Western Antarctica. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Rapid warming of mean air temperature by 0.17 °C per decade has been recorded over the last 50 years in the Western Antarctic Peninsula (WAP) region (Steig et al., 2009; Thomas et al., 2009; Turner et al., 2005), with the major rise in air temperature occurring during the autumn–winter months (Kejna, 2003). At King George Island/25 de Mayo (KGI), South Shetlands, monthly air temperature means in- creased on average by 1.1 °C between 1947 and 1995 and by 1.9 °C if only the winter months are considered (Ferron et al., 2004). Aerial warming in West Antarctica has been associated with retreating fronts and increased ice mass loss of land glaciers (Cook et al., 2005). These melting ice masses contribute to the globally rising sea level (Vaughan, 2006; Vaughan et al., 2003), increasing water column stratification, es- pecially in shallow coastal environments of the WAP. Glacier run-off transports high particle loads, affecting water column light properties and changing the optical conditions for phytoplankton photosynthesis in coastal areas (Dierssen et al., 2002; Schloss et al., 2002). The specific fresh water discharge volume (i.e., hm 3 km -2 glacial catchment area) shows large differences between austral spring/summer melting sea- sons, and the number of annual discharge days and the daily discharge volume has doubled at KGI within the short period from 2002 to 2006 (Dominguez and Eraso, 2007). Sea water temperatures have been stable for a period of at least 10 million years around Antarctica, one of the thermally most stable environments on Earth (Peck, 2005). Now evi- dence is accumulating for a recent significant warming in surface wa- ters (Meredith and King, 2005; Whitehouse et al., 2008; for review see Clarke et al., 2009). Changes in water temperature strongly affect the ecology and physiology of marine ectotherms and warm blooded top predators such as penguins, and major changes in benthic and Journal of Marine Systems 92 (2012) 53–66 ☆ This work is dedicated to the memory of Augusto “Alfa” Thibaud and Teófilo González, who lost their lives in a glacier crevasse near Jubany during the overwintering in 2005. ⁎ Corresponding author at: Instituto Antártico Argentino, Cerrito 1248 C1010AAZ Ciudad Autónoma de Buenos Aires, Argentina. Tel.: +1 418 723 1986x1391; fax: +1 418 724 1842. E-mail addresses: ischloss@dna.gov.ar, Irene_Schloss@uqar.ca (I.R. Schloss). 0924-7963/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jmarsys.2011.10.006 Contents lists available at SciVerse ScienceDirect Journal of Marine Systems journal homepage: www.elsevier.com/locate/jmarsys