Humans have spread organisms widely across the Earth, many of them unintentionally, through commerce, exploration and travel. Some of these organisms are versatile and can adapt to and thrive in new environments. Globally, this movement of organisms by humans to areas beyond their natural ranges (often then referred to as non-native species) is responsible for major changes in ecosystem structure and functioning, reductions of biodiversity, and negative economic impacts (1).
Antarctica and its associated and dependent ecosystems are under increasing pressure from the unintentional introduction of non-native species (2-7). Increased human activity in the region increases the likelihood of arrival and establishment of non-native species (2). Increased human activity within the Antarctic increases the likelihood of arrival and establishment of native species to biogeographic regions outside of their natural ranges (2, 3, 5). This, in turn, could increase the likelihood of altering the distinct biogeographic regions within Antarctica.
There is evidence that mainly terrestrial and some marine non-native species are introduced inadvertently to Antarctica in significant numbers (2-6). Seeds and soil are transported on clothing and personal belongings, and organisms are also transported during shipping, construction and general logistical activities (2-6). Some of these non-native species are known to have established, some have persisted for many years, and some have expanded their ranges and become invasive (5, 8, 9). Experience from environments around the world and from comparable environments in the Arctic and sub-Antarctic suggests that invasive species in Antarctica could have substantial environmental, financial and irreversible impacts on Antarctic ecosystems (1, 7, 10). In the sub-Antarctic, non-native grazing vertebrates and plants have altered native plant assemblages, non-native rodents and cats have greatly reduced bird populations, and non-native insects have altered nutrient turnover and decreased local insect abundances (3, 7).
Impacts resulting from the introduction of non-native species to Antarctica, and from moving native Antarctic species within Antarctica are likely to be exacerbated by climate change (2). The climate in some parts of Antarctica is changing dramatically, increasing the likelihood that non-native species could become established (4, 10). A continent-wide risk assessment for the establishment of non-native species in Antarctica demonstrated a substantial increase in the likelihood of establishment at key locations in the future (2, see Figure 1).
The Protocol on Environmental Protection to the Antarctic Treaty (the Protocol) aims to protect comprehensively Antarctica's environment and its dependent and associated ecosystems. This includes prohibiting the intentional introduction of non-native species to the Antarctic Treaty area except in accordance with a permit (which can only be issued under prescribed circumstances).
In 2011, following several years of development by the CEP, the Antarctic Treaty Parties recognised that the introduction of non-native species to the Antarctic region, including the movement of species between locations within the region, represents a serious risk to biodiversity and to the intrinsic values of Antarctica. By means of Resolution 6 (2011) Antarctic Treaty Consultative Meeting XXXIV (ATCM) also adopted a Non-native Species Manual, including guidelines and resources to assist Parties to meet the following agreed objective for further work on this issue:
To conserve Antarctic biodiversity and intrinsic values by preventing the unintended introduction to the Antarctic region of species not native to that region, and the movement of species within Antarctica from one biogeographic zone to any other (Non-native Species Manual).
Reducing the risk of the transfer of species between sites in Antarctica has been a recent focus of work to manage non-native species risks. In 2012 CEP XV endorsed 15 distinct Antarctic conservation biogeographic regions (11). The delineation of these biologically distinct regions supports the management of non-native species risks associated with moving between regions within Antarctica.
Increased pressures on Antarctic systems from climate change and increased human activity can increase the risk of non-native species introduction and range expansion (3, 5, 11, 12). Therefore, continued research into the impacts of non-native species and widespread adoption of practices to reduce their introduction and spread, and respond to introductions are integral to the protection of the Antarctic and its associated ecosystems.