Multiyear changes in distribution and abundance of Salpa thompsoni in the Western Antarctic Peninsula region

The most common and widespread salp in the Southern Ocean is Salpa thompsoni. It is characterized by a circumpolar distribution and its appearance is clearly associated with the occurrence of the Antarctic Circumpolar Current (ACC). This area of the Southern Ocean is characterized by a relatively low productivity and high water temperature. In recent years the expansion of distribution range of this invertebrate species has been observed. This process may be a result of the ACC southward movement, which is caused by ocean warming and variability in sea ice extent. The presented time series is based on samples collected between 1975 and 2001 in the region of Western Antarctic Peninsula. The results of laboratory analyses, coupled with environmental data, obtained both during sampling and from satellite data, allowed to prove that the distribution of salps was significantly correlated with water temperature and presence of sea-ice, while their abundance resulted from salinity and temperature. The results of our study suggest that with climatic changes, such as temperature increase and reduction of sea-ice cover, the distribution range and abundance of Salpa thompsoni is likely to increase in the Western Antarctic.