The past two and a half centuries of marine biological work in the Southern Ocean have resulted in a vast catalogue of living organisms. During this time there have been several attempts to classify distinct regional biodiversity patterns in the seas around Antarctica. The recent publication of the SCAR Biogeographic Atlas of the Southern Ocean represents the most comprehensive international effort to date. The complete database represents 1.07 million occurrence records (from Antarctic and neighbouring waters) for 9,064 recognised species from ~434,000 distinct sampling stations. It highlights the hotspots of biodiversity and areas of high levels of sampling, as well as identifying areas, geographical and taxonomic, which require substantial future investigation. It also utilises habitat modelling methods to predict species and community distributions. This compilation serves as a vital benchmark of current biodiversity knowledge and as a significant tool for future scientific, conservation and resource management planning.
Over 400 lakes exist beneath the Antarctic ice sheet. They range from giant stable lakes at the centre of the ice sheet, isolated from the atmosphere for millions of years, to small through-flow pockets of water beneath fast-flowing ice streams. Subglacial lakes likely harbour unique micro-organisms, adapted to the extreme conditions such as pressure and darkness under the ice, and records of ice and climate change from when the ice sheet first formed. Uncovering their microbiological and climatological secrets requires direct access and sampling of these pristine environments. SCAR has been involved in guiding plans for subglacial lakes access and exploration, ensuring experiments are conducted in a safe, clean and environmentally sustainable manner. A formal code of conduct was accepted by the ATCM in 2011 and a revised version endorsed in 2017. To date, only two lakes at the edge of the West Antarctic ice sheet have been sampled cleanly for water and sediment - subglacial lakes Whillans (in January 2013) and Mercer (in December 2018).
There have been relatively few wildlife mass mortality events reported in Antarctica that can be conclusively attributed to infectious disease. Climate change and increasing human activity in the region may increase both the risk of pathogen transmission and the frequency of mortality events. Information on the presence of pathogens and diseases in birds and marine mammals is limited and fragmented, being based on relatively few species and locations. Despite concerns about the introduction of non-endemic pathogens, structured Antarctic wildlife health surveillance programs have not been established, making it difficult to assess the implications of disease for conservation actions. To achieve a sound health surveillance program, long-term investigations are essential to identify both host species and monitoring locations to detect emergent pathogens, as well as to better characterise the viral, microbial and parasitic communities, both native and introduced, in Antarctica and their effects on host physiology, fitness and survival.
Historical operational practices have left waste disposal and abandoned work sites in many locations in Antarctica. Many countries have undertaken clean-up activities in order to minimise ongoing environmental impacts at these sites, but many sites remain that require attention. The environmental impacts at these sites are expected to increase over time, as structures and containers continue to degrade. The practical difficulties and escalating costs of clean-up increase the urgency of undertaking remediation actions in a timely manner. The Protocol on Environmental Protection to the Antarctic Treaty (the Protocol) includes requirements that aim to prevent the creation of further contaminated sites. It also requires that existing sites be cleaned up, provided that doing so does not result in greater adverse environmental impact. The Committee for Environmental Protection (CEP) is continuing to to develop a Clean-Up Manual intended to comprise a central repository of best-practice guidance for these efforts. Much work remains to develop agreed environmental quality targets, remediation / clean-up technologies, and monitoring and evaluation customised to the Antarctic and individual sites.
Inland waters are widely distributed across Antarctica and many have characteristics found only in polar regions. We summarise the diversity of inland aquatic ecosystems and characteristics that make them vulnerable to direct human intervention and environmental variability and change. Primary sources of surface water are ice and snow, rarely rainfall (except in the Maritime Antarctic), restricting flow to the summer melt. Groundwater and sub-glacial systems have been identified but are largely un-investigated. Seasonal freezing imparts considerable variability to the physical habitat of near surface ecosystems. Some water bodies are already impacted by station usage and continuous field investigations that may leave legacies of disturbance. Climate change will greatly alter inland water ecosystems of the continent. Management of direct human activities is through ASPAs, ASMAs and SCAR Codes of Conduct for ‘Terrestrial Scientific Field Research in Antarctica’ and ‘Exploration and Research of Subglacial Aquatic Environments’, with national programme overlays.
Annex III to The Protocol on Environmental Protection to the Antarctic Treaty requires that past and present terrestrial waste disposal sites and abandoned work sites be remediated unless removal by practical means would result in greater adverse environmental impacts. Past remediation has focused on clean-up of former waste sites, removal of disused infrastructure and other debris and removal/remediation of contaminated soils. Remediation efforts have been hindered by lack of comprehensive remediation guidelines and clean-up protocols. High costs, logistical difficulties and environmental risks involved in extracting, transporting and disposing of waste present additional barriers to remediation of Antarctic contaminated sites.
Human activity in Antarctica has the potential to cause disturbance to wildlife. In severe cases, human disturbance to wildlife can cause declines in breeding success, physical harm and even sometimes, direct mortality. Human disturbance can also induce physiological stress responses, which translate into animal behavioural responses like increased vigilance or fleeing behaviour, or avoidance of disturbed areas. Human disturbance effects vary as a function of extrinsic factors such as the type of disturbance, its form, magnitude and frequency. Different species, and even different populations of the same species, show widely differing responses to human disturbance. This variability means that generalisations of the impact of human disturbance to Antarctic wildlife cannot yet be made, and at least with current knowledge, a single effective set of guidelines for all Antarctic species is unlikely to be achieved.
There is a large amount of information on birds in Antarctica but this has never previously been assembled and analysed to determine exactly where the most significant breeding sites for the avifauna as a whole are. Such information is essential in order to inform the conservation actions needed to protect them against the range of threats identified in Antarctica. These include direct disturbance by visitors, disturbance by aircraft or vehicles, exposure to pollutants, ingestion of or fouling by marine debris, competition for prey from fisheries, accidental by-catch on fishing lines or in nets, introduction of disease from other parts of the world and climate change. Recent analyses have identified 204 Important Bird Areas (IBAs) in Antarctica, for all of which detailed site accounts have been compiled. Sites were identified using internationally agreed criteria that have been applied in 200 countries over the past 35 years. The compiled list of IBAs provides a baseline against which change can be measured and conservation actions considered.
Antarctica's biodiversity and its intrinsic values are potentially at risk from the introduction of non-native species, derived from a range of sources including human activities. Whilst controls on introducing plants and invertebrates are now in place, limited attention has so far been given to microorganisms that comprise the majority of the Antarctic terrestrial biomass, and are highly dispersive. Information deficits and likely impacts in a warming climate indicate that this should be given a higher research priority, particularly in ice-free areas where the range of microbial habitats for colonisation is higher.
Non-native organisms are relatively rare in Antarctica and the Southern Ocean. This is probably attributable to the comparatively recent human presence and to protection afforded by the Protocol on Environmental Protection to the Antarctic Treaty, which prohibits deliberate introductions. Inadvertent introductions do occur, as clothing and luggage of visitors, cargo, fresh produce, vehicles, ships and other means of transport can inadvertently entrain propagules or complete organisms. Because of steadily growing human activities on the continent and climate change trends, the risk of non-native organisms arriving and establishing is likely to increase.
Climate models are the main tool for making quantitative estimates of how Antarctic climate may change over the 21st century. There is high agreement on some aspects of the predictions provided by models, but improvements in understanding are needed in key components of the Antarctic climate system, such as sea ice and coastal ocean-ice shelf processes. In the near term (on timescales of a few years) the climate change signal is small compared to natural cycles (associated with phenomena such as El Niño), the remote impacts of which on the Antarctic atmosphere are difficult to predict. In the longer term (on multi-decadal timescales) the reliability of climate model predictions is limited by uncertainty over human emissions pathways, the realism of climate models, and feedbacks between other elements of the Earth System (e.g. ice sheets).
The Ross seal is one of four marine carnivores that breed in sea-ice habitats around Antarctica. Ross seals are not often seen because they breed and moult in difficult to reach areas of heavily congested pack ice and then apparently spend the rest of their lives in the open ocean. Consequently, their biology and ecology are poorly known and they have been presumed to be rare. The original reason for declaring the Ross seal a Specially Protected Species was principally because there were too few data to make any judgement about their abundance . The few surveys by icebreaker and aircraft estimated abundance ranging from 20,000 to 220,000. The genetically effective population size of Ross seals in the Antarctic was estimated at around 130,400 from analyses of mitochondrial DNA and about 254,000 from analyses of nuclear DNA microsatellites. Genetic data suggest that the species has been increasing over geological time and there is no evidence for any recent decline in abundance. The species has not been commercially hunted, and very few have been collected for scientific studies.
The Southern Ocean around Antarctica is complex and especially difficult to investigate as harsh conditions often limit oceanographic sampling. Given the range of physical, chemical, and biological processes that need to be investigated over a wide range of spatial and temporal scales, a broad suite of technologies is needed to collect data. New observational technologies are continually becoming available to oceanographers. Satellites and ship sampling are core approaches used to map ocean properties and are complemented by fixed assets include moorings and shore-based systems. Mobile platforms include profiling floats, gliders and autonomous underwater vehicles can provide spatial maps of subsurface data. Numerical models are a further crucial tool in building our understanding of marine ecosystems and processes as well as the linkages between sea and atmosphere. The coupled observational and modeling networks together provide a critical basis for improving our understanding of the ocean and predicting its likely future state.
The discharge of sewage and wastewater into the Antarctic environment represents a serious and significant risk of environmental impacts that includes the introduction of non-native micro-organisms and pathogens, genetic pollution and accumulation of, and exposure to, contaminants. Wastewater discharges could lead to long term impacts on wildlife health, biodiversity and community structure in the vicinity of Antarctic stations. Treatment and disposal practices vary widely, as each Party to the Antarctic Treaty determines their own standards with varying interpretation of requirements under the Protocol on Environmental Protection. Further research and monitoring of the impacts of wastewater on Antarctic ecosystems will assist in quantifying the potential risks and impacts. Currently, no guidelines exist that describe permissible levels of bacteria, chemical and other contaminants being discharged from outfalls within the Treaty area, but their development would be beneficial in setting a baseline for monitoring. One of the highest priorities of the Committee for Environmental Protection (CEP) is addressing the introduction of non-native species. Wastewater discharge is a significant source of potential introductions, but advanced wastewater treatment could substantially reduce this and other associated risks.
Annex V to the Protocol on Environmental Protection to the Antarctic Treaty (the Protocol) establishes a framework for designating Antarctic Specially Protected Areas (ASPAs) and Antarctic Specially Managed Areas (ASMAs). These areas are intended to support the objective of protecting comprehensively the Antarctic environment. There are 72 ASPAs and 6 ASMAs currently. ASPAs are sites with outstanding environmental, scientific, historic, aesthetic or wilderness values, any combination of those values, or ongoing or planned scientific research that warrant additional protection due to these values or the risks of human impacts on these values. Important work has been done to underpin the development of a representative series of ASPAs, including spatial analyses to identify distinct ‘Environmental Domains’ and ‘Antarctic Conservation Biogeographic Regions’. The Antarctic Treaty Parties have agreed that these spatial frameworks are useful references to guide the designation of ASPAs within a systematic environmental-geographic framework, and the Committee for Environmental Protection (CEP) has recognised the need for a more systematic approach to the development of the protected area system.
Antarctic biodiversity and ecosystems are under threat from introduced non-native species. Currently the Antarctic Peninsula and off shore islands are the most invaded areas. Invasions are likely to increase, facilitated by climate change and increased human activity in the region. Despite success in eradication of non-native plants, established non-native invertebrate species have already begun to increase their distribution within Antarctica with largely unknown impacts upon native organisms and habitats. Further scientific research could usefully investigate surveillance and detection techniques, the rate and extent of microbial and marine introductions, rates of transfer of native and non-native species between Antarctica eco-regions, and devise optimal prevention and ultimately eradication methodologies.
Antarctica's biodiversity and its intrinsic values are at risk from the introduction of non-native species, predominantly facilitated by human activity. Non-native species, or species that live outside of their natural range, can spread inter-regionally (from outside the Antarctic and its associated and dependent ecosystems) or intra-regionally (within the Antarctic and its associated and dependent ecosystems). Research suggests that non-native species in Antarctica could have substantial environmental, financial and irreversible impacts on Antarctic ecosystems and biodiversity. Research also suggests that the risk of establishment of non-native species is likely to increase with climate warming. Given the likelihood of increased pressures on Antarctic ecosystems from non-native species, addressing non-native species introductions is one of the highest priorities of the Committee for Environmental Protection (CEP). The CEP has acknowledged that continued research on the impacts of non-native species and the adoption of practices to reduce their introduction and spread are needed.
Most Southern Ocean life is specifically adapted to the unique Antarctic environment. This extensive region is characterized by low temperature, a glaciated coastline and distinct seasonality in sea-ice cover, light regime and biological productivity. Here, we examine the vulnerability of Southern Ocean biota to recent changes to inform society and stakeholders about primary areas of concern and the most pressing fields for future study. Most species inhabiting the Southern Ocean are assumed to be sensitive to climate change. Growth of microalgae, the base of the food web, depends critically on sea-ice cover. Predicted sea-ice reduction will have cascading effects on higher trophic levels. Organisms living in the ice, krill, fish, penguins, seals, and whales will need to find new habitats or feeding grounds. However, thresholds of climatic conditions for population or community collapse are largely unknown. Some organisms might even benefit from climate change through increased reproduction and growth rates.