Conserving Antarctic biodiversity in the Anthropocene

Abstract

Anthropogenic activity threatens biodiversity worldwide, with the species and ecosystems of even the most remote and largest remaining wilderness at risk. In Antarctica, human activity is growing, barriers to invasive species establishment are being lowered, pollution is pervasive, and climate change directly and indirectly threatens taxa across the region. This has the potential to impact some of the world’s most unusual, isolated, and highly-adapted species. Evolving in isolation for long periods, a number of specialised lower plants and invertebrates dominate Antarctic ecosystems, with mosses, lichens, microbes, arthropods and soil microfauna present across the continent. Seals and seabirds breed in coastal regions and two flowering plants survive in the milder conditions of the Antarctic Peninsula. In this thesis I provide crucial impact assessments for some of the key processes threatening Antarctic biodiversity, and produce the first inclusive, continent-wide prioritisation of management strategies for conserving Antarctic biodiversity in the face of multiple threats, which will help to inform decision makers in identifying cost-effective conservation strategies.The vast majority of Antarctic life survives only in the less than 1% of the Antarctic continent that is permanently ice-free, where soils and rocks areas emerge as nunataks, dry valleys, cliffs, fellfields, and coastal oases. Despite being crucial habitat, we have limited understanding of how ice-free areas will be impacted by climate change. In Chapter 2 I use temperature-index melt modelling to determine the potential impacts of climate change on Antarctic biodiversity habitat. I found the distribution and extent of ice-free areas may rapidly change in the future, with up to 25% more ice-free area potentially available by the end of the century. The increasing habitat availability and increasing connectivity is likely to benefit some native taxa, yet will also provide opportunities to non-native species, who pose one of the greatest threats to Antarctic biodiversity. Spread of both native and non-native species into isolated regions could result in increased genetic homogenisation and reduced diversity.The milder coastal ice-free areas are home to great numbers of Antarctic taxa, as well as most sites of human activity, taking the form of scientific research facilities and tourist landing sites. Many of these low-lying sites may be impacted by sea-level change, yet there have been no comprehensive assessments of potential impacts for the Antarctic continent. In Chapter 3 I use three sea-level rise (0.5 m, 1 m, 2 m) and two sea-level fall (0.5 m, 1 m) scenarios to consider potential impacts of sea-level change on Antarctic biodiversity and human activity. I found sea-level rise could inundate prime coastal ice-free area, placing numerous research facilities, tourist landing sites, breeding penguin colonies and biodiversity hotspots at risk. Sea-level fall could further expose new ice-free areas and increase the distance to the coast for biodiversity and human activity. The consequent movement of humans and biodiversity could result in human-biodiversity conflict as competition for space increases beyond current levels. High-resolution, regional assessments are urgently needed for key at-risk sites across the continent to facilitate inclusion of conservation priorities in management plans.Antarctic tourism emerged in the 1950s and has grown steadily ever since. It is predicted that visitor numbers will continue to increase, and concerns have arisen over the potential environmental impacts of the industry. In Chapter 4 I assemble long term tourist records from the International Association of Antarctica Tour Operators and use them to analyse trends across the continent. I then make projections for changes in tourist landing site distribution and intensity under future climate, providing the first quantitative assessment of how the Antarctic tourist industry may change into the future. I found the intensity of landing sites in the Antarctic Peninsula may increase substantially and that new suitable sites may emerge around the rarely-visited and more isolated coast of East Antarctica. Increasing visitation to remote regions will provide new opportunities for non-native species transfer and greater numbers of sites will lead to increased likelihood of human impact on the environment beyond minor or transitory effects.With the growing number and intensity of threats predicted for Antarctic biodiversity into the future it is essential that policymakers have access to evidence-based conservation strategies. In Chapter 5 I use a decision support framework, based on expert elicitation, to prioritise conservation actions for terrestrial Antarctic biodiversity across the entire continent and produce the first threat-targeted, inclusive conservation plan. I found that influencing global policy to mitigate climate change would provide the greatest benefit to Antarctic biodiversity, followed by managing non-native species and managing and protecting individual species. Cost-benefit analysis further revealed that influencing global policy, modifying human behaviour on the ground, and managing transportation were highly cost-effective and require greater representation in the policy forum.Together these chapters form some of the first continental assessments of threats to terrestrial Antarctic biodiversity and culminate in the first cost-effective prioritisation of conservation strategies at the continental scale.