Long term hydrographic conditions and climate trends in Potter Cove

IRENE SCHLOSS; GUSTAVO FERREYRA; OSCAR GONZÁLEZ; ADRIÁN ATENCIO; VERÓNICA FUENTES; GABRIELA TOSSONOTO; GUILLERMO MERCURI; RICARDO SAHADE; MARCOS TATIÁN; DORIS ABELE

POLARFORSCHUNG

Año: 2008 vol. 571 p. 382 - 389

0032-2490

A marked warming of mean air temperature has been recorded over the last 50 years in the Western Antarctic Peninsula (WAP) (see Turner et al., 2005 and references therein). This rise in air temperature was mainly observed during the autumn-winter months (Kejna, 2003). In particular, in King George Island (25 de Mayo), South Shetlands air temperature rose on average by 1.1 oC between 1947 and 1995 (Ferron et al., 2004); if only the winter months are considered, temperature increase in the same period amounts to 1.9 oC. This trend was also apparent in the air temperature data from the meteorological station in Jubany station for the decade 1994-2004 (Schloss, 2003). Climate warming in Antarctic environments has been associated with glacier retreat and increased ice melting (Cook et al., 2005) which, in turn, change the vertical structure of the water column, especially in Antarctic shallow coastal environments in the WAP. Moreover, glacier runoff has been shown to transport high particle loads, affecting water column light climate and changing the optical conditions for phytoplankton photosynthesis. Light and salinity changes are, therefore, indirect consequences of regional air temperature increase. A direct effect on sea water temperature could also be expected, although so far no increase in sea water temperatures has been reported for Antarctic waters. Although stable sea water temperatures have been recorded around Antarctica for a period of at least 10 million year (Peck, 2005), making it one of the most thermally stable environments on Earth there is already some evidence on surface water temperature warming (Meredith and King, 2005). Since the beginning of the Argentinean – German cooperation at Jubany Station – Dallmann laboratory, sea water temperature and salinity, as well as chlorophyll-a and suspended particulate matter concentrations have been measured in Potter Cove, in the vicinity of the station. Several projects, using hydrographical data as central or complementary information were carried out. As a result, a 15-years series of data is available, although there are many gaps, especially in the winter months, when difficult weather conditions made sampling  impossible. In the present  paper, a preliminary analysis of these series is presented and discussed in the face  of  climatic change(warming)  observed in the WAP  coastal ecosystems.