Deep-Sea Research II 53 (2006) 853–865 Spatial and temporal variation in shallow seawater temperatures around Antarctica David K.A. Barnes a,Ã , Veronica Fuentes b , Andrew Clarke a , Irene R. Schloss c , Margaret I. Wallace a a British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 OET, UK b Alfred-Wegner-Institut, Columbustrasse, D-2750 Bremerhaven, Germany c Instituto Anta´rtico Argentino, Cerrito 1248 (C1010AAZ) Buenos Aires, Argentina, and CONICET, Argentina Received 5 June 2005; accepted 3 March 2006 Abstract The variability of Southern Ocean sea-surface temperatures (SST) are important to understanding coastal biology yet are poorly known amongst biologists. We compare sea temperatures at a constant depth (10–20 m) at coastal localities both sides of the Polar Front (PF), around the Scotia-Arc, the West Antarctic Peninsula and at high oceanic latitudes (around the margins of East Antarctica). We assess the wider context of these values by investigating minimum and maximum temperatures and ranges throughout the Southern Ocean using remotely sensed SST data. Data to date show weekly, daily and hourly variation in shallow sea temperature can be one-third of total annual variability (in the summer) but can be very constant (in winter). From comparison across scales in time and space, the strong seasonal signal is the most striking feature of Antarctic shallow sea temperatures even at highest oceanic latitude sites. The winter sea temperatures at localities within the PF are similar (near freezing), but upper temperatures and thus the annual range vary predictably with latitude in a cline. This amounts to 0.2 1C annual range/100 km of latitude between 541S and 671S. The annual range in sea temperatures is little different at SubAntarctic islands, whether they are north or south of the PF. r 2006 Elsevier Ltd. All rights reserved. Keywords: Southern Ocean; South Georgia; King George Island 1. Introduction Although oceanographic observations have been made widely around Antarctica, there are still relatively few direct subsurface measurements from coastal or nearshore locations south of 681S in west Antarctica, on the east side of the Antarctic Peninsula, or around most of East Antarctica; these gaps comprise the majority of the coastline of Antarctica. As a result, our current understanding of patterns of temporal and spatial variability in seawater temperature in the shallows is limited, as evidenced by the citation of data from very few locations around Antarctica. Even definitions of which water comprises the Southern Ocean can differ: typically marine biologists refer to it as inside the Polar Front (PF), whilst oceanographers define it as inside the northern edge of the Antarctic Circumpolar Current (ACC). It is known that the Southern Ocean was warm during the late Mesozoic, ARTICLE IN PRESS www.elsevier.com/locate/dsr2 0967-0645/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.dsr2.2006.03.008 Ã Corresponding author.