Antarctic biosecurity policy effectively manages the rates of alien introductions

Abstract

Reducing the rates and impacts of biological invasions is a major policy goal of international biodiversity agreements. Yet the extent to which this goal is being achieved and the agreements hence successful in this respect remains unclear. Here we use a comprehensive record of alien species introduction in the terrestrial Antarctic, including its surrounding Southern Ocean Islands, spanning 115 years (1900-2015), to quantify the impact of biosecurity policy on alien species introduction rates in the region, where invasive alien species are a primary environmental conservation threat and management priority. We show that although many parts of the Antarctic have been colonised by non-indigenous taxa, recent rates of introduction appear to be slowing or static in most parts, compared with increases in the past. Our results vindicate the regional Antarctic focus on biosecurity measures, but also demonstrate the need for stricter enforcement due to rapid socio-environmental changes. Three key pointsO_LIBiological invasions present a large and growing threat to Antarctic ecosystems under climate change and expanding human activity C_LIO_LIOver the 20th century, there was no trend in alien species introduction rate in five Antarctic regions and a significantly increasing trend in the remaining five regions C_LIO_LIDespite this variation, in most regions, the number of introductions remains low, indicating that Antarctic biosecurity has been effective at slowing the rate of introduction C_LI