Distribution of Enteric Bacteria in Antarctic Seawater Surrounding the Dumont d’Urville Permanent Station (Adélie Land)

The survival of human enteric bacteria in the aquatic environment has attracted much interest in view of its public health significance. Untreated sewage has been released from Dumont dʹUrville station, Antarctica, into the Southern Ocean for several years. The spatial distribution of faecal bacteria indicators was investigated in summer ice-free seawater near the French Base station of the Adélie land area. A complementary seasonal survey of the occurrence of faecal coliform bacteria was conducted in seawater under the winter sea ice in a specific station. Relatively high bacterial densities (maximum 103 CFU 100 ml−1) were found in seawater surrounding the sewage outfall. However, the contamination decreased rapidly with increasing distance from the outfall. In all samples collected further than 2 km, the bacterial indicators were absent or present in very small numbers. Faecal coliforms were not detected in samples collected at pristine sites. Despite these relatively low contamination levels, faecal bacteria were always detected in the vicinity of the sewage outfall during the seasonal survey conducted in ice and under-ice seawater.