Global shipping traffic is considered one of the most important causes of animals being trafficked worldwide and being introduced into ecosystems that are new to them – with sometimes catastrophic consequences if these species become invasive. Antarctica is also now at great risk as a result, as a study by David Aldridge from the University of Cambridge and his team in "PNAS" shows. "Invasive, non-native species are one of the biggest threats to the biodiversity of Antarctica, because the native species have been isolated in the last 15 to 30 million years. They can also have an economic impact by disrupting fishing," says Aldridge.
Antarctic is now connected to at least 1581 ports via catch, research and tourist ships from which the ships come from or where they stop. Animals can get "on board" everywhere, for example through the ballast water that is absorbed in the harbor, or if they settle on the ship's cover. Various mussels, lake rocks, crabs and algae that can come from all parts of the world are particularly common - also from regions such as the Arctic, whose climate resembles that of Antarctic.
These species worry Aldridge and Co the most: Arctic species are far more likely to survive in Antarctica than related species from the mid-latitudes or even the tropics. In addition, many cruise and research ships sail to the Arctic in the northern summer and the Antarctic in the southern summer, so that a relatively direct exchange takes place here. Fishing vessels, on the other hand, mainly head for the same ports in a few countries. However, cruise ships only stay on site for a short time, while research and supply vessels anchor much longer in ports and in the Antarctic, which significantly increases the risk of importation.
Because of its relatively strong isolation from the strong circumpolar currents for millions of years, an animal world was able to develop in Antarctica. In contrast, some brands such as shallow water crabs are missing. If these are introduced, they can affect ecosystems: shallow water crabs, for example, live robbery, while the antarctic species lack the corresponding antiders against these animals.
"We were surprised to find that Antarctica is much more globally connected than previously thought. Our results show that biosecurity measures need to be implemented in a larger number of locations than is currently the case," says Arlie McCarthy of the British Antarctic Survey, who was involved in the study. So far, the Southern Ocean is considered the only large marine region in which no invasive species have yet been identified. In order to maintain this, ship hulls are already being freed from clinging species in some important ports. This must now be expanded, the working group demands.
