Human-mediated dispersal of terrestrial species between Antarctic biogeographic regions: a preliminary risk assessment

The distribution of terrestrial biodiversity within Antarctica is complex, with 16 distinct biogeographic regions (Antarctic Conservation Biogeographic Regions) currently recognised within the Antarctic continent, Peninsula and Scotia Arc archipelagos of the Antarctic Treaty area. Much of this diversity is endemic not only to Antarctica as a whole, but to specific regions within it. Further complexity is added by inclusion of the biodiversity found on the islands located in the Southern Ocean north of the Treaty area. Within Antarctica, scientific, logistic and tourism activities may inadvertently move organisms over potentially long distances, far beyond natural dispersal ranges. Such translocation can disrupt natural species distribution patterns and biogeography through: (1) movement of spatially restricted indigenous species to other areas of Antarctica; (2) movement of distinct populations of more generally distributed species from one area of Antarctica to another, leading to genetic homogenisation and loss of assumed local patterns of adaptation; and (3) further dispersal of introduced non-native species from one area of Antarctica to another. Species can be moved between regions in association with people and cargo, by ship, aircraft and overland travel. Movement of cargo and personnel by ship between stations located in different biogeographic regions is likely to present one of the greatest risks, particularly as coastal stations may experience similar climatic conditions, making establishment more likely. Recognising that reducing the risk of inter-regional transfer of species is a priority issue for the Antarctic Treaty Consultative Meeting, we make practical recommendations aimed at reducing this risk, including the implementation of appropriate biosecurity procedures