According to IPCC (2001), climate change in polar regions is expected to be greater and more rapid than in other regions and will cause major physical and ecological impacts, especially in the Antarctic Peninsula and Southern Ocean. The break-up of ice shelves further south in the Antarctic Peninsula and changes in marine and terrestrial ecosystems (e.g. the introduction of exotic plants and animal species) are among the most probable effects of warming and increased precipitation. The physical oceanography and ecology of the Southern Ocean will change, and the projected reduction in sea-ice extent will alter phytoplankton spring blooms in the marginal sea-ice zone, with profound impacts on krill and all levels of the pelagic food chain. Marine mammals and birds linked to specific breeding sites will be affected by environmental changes or changes in the availability of prey species. Warming (by 4-5 °C) of the western Antarctic Peninsula over the past 50 years changed spatio-temporal patterns of winter sea-ice formation and probably contributed to a significant increase in chinstrap penguin populations and a reduction in Adelie penguin populations (Fraser et al. 1992; R.C. Smith et al. 1999). The two species of seabirds have similar diets and breeding ranges in the peninsula, but the increasing availability of open water is unfavourable to an obligate inhabitant of pack ice such as the Adelie penguin. This is just one example of the importance of long-term monitoring programmes on penguins and other key Antarctic species.
Within the framework of the CCAMLR Ecosystem Monitoring Program (CEMP) and in collaboration with Italian researchers, since 1989 the Australian Antarctic Division has undertaken long-term monitoring studies on
Adélie penguins in East Antarctica (e.g. Gardner et al. 1997; Clarke et al. 1998). Although the main aim of the CCAMLR programme was to evaluate whether krill harvesting adversely affects elements of the Antarctic marine food chain, studies on penguin populations (especially those on food consumption and breeding success) may also help detect annual and long-term effects of climate change on sea-ice extent, krill distribution and abundance, and on inputs of persistent contaminants from other continents of the Southern Hemisphere. Fraser and Hofmann (2003) examined the long-term foraging response of Adélie penguins to ice-induced changes in krill recruitment and availability near Palmer Station (western Antarctic Peninsula). They found a causal relationship between change in ice cover, krill availability and penguin foraging strategies. During the last two decades, krill populations were sustained by strong age classes which emerged episodically every 4 or 5 years. Fraser and Hofmann (2003) hypothesise that cohort senescence has become an additional ecosystem stressor in an environment where enhanced warming is deteriorating sea-ice conditions conducive to good krill recruitment. Their results suggest that at least one "senescence event" has already occurred in the western Antarctic Peninsula region, with a decrease in krill abundance, penguin foraging, and breeding performance and populations. It was therefore suggested that krill longevity should be incorporated into models on causal links between climate, physical forcing and ecosystem response.
Monitoring is an essential element of environmental management, and a number of national Antarctic programmes perform environmental monitoring near scientific stations. The most common monitoring activities include: the determination of atmospheric pollutants associated with station activities; the quality of sewage and wastewater; levels of hydrocarbons, trace metals and other pollutants in snow, water, soils or sediments; animal population counts and breeding success of penguins and other Antarctic birds; studies on benthic marine communities and the use of some species of benthic organisms as bioaccumulators or biomarkers of persistent pollutants in more impacted marine coastal ecosystems. A summary of monitoring activities performed by national programmes in Antarctica has been prepared by COMNAP-AEON (2001). Standardised approaches are essential to determine spatio-temporal variations in environmental contaminants or organism populations. During the last decade, efforts were made to develop international coordination of monitoring procedures, quality assurance and data management (e.g. the handbooks published by SCAR/COMNAP 1996,2000). Human activities and their impact must be monitored to improve Antarctic environmental management, meet the legal requirements of the Protocol on Environmental Protection to the Antarctic Treaty, and evaluate the effectiveness of existing conservation measures. These surveys are generally performed in relatively small areas around scientific stations or field camps, but in Antarctica there is also a need for large-scale monitoring of global phenomena.
Regional- or continental-scale surveys are necessary to establish baselines, to improve our understanding of environmental processes and functioning of Antarctic ecosystems, and to verify predictions concerning atmospheric processes and the deposition of long-range transported contaminants. Monitoring of global changes and observed changes in the Antarctic environment should ensure that the environmental impact during sampling and fieldwork is minimal and sustainable (i.e. that it does not compromise the significance of the study area for future observations on global-change processes). Therefore, whenever possible, it is advisable to adopt sampling strategies based on large time intervals (possibly some years) and not requiring the use of electric power generators or other sources of environmental contaminants.
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