Issue date: 29 Aug 2002
PR No. 8/2002
Recent changes in Antarctic seabird populations may be linked to environmental change according to scientists reporting in the journal Science
this week. Researchers from the Cambridge-based British Antarctic Survey (BAS) reviewed the best available data from a range of long-term studies to test the view that warming of the Earth?s climate is affecting Antarctic marine life. Whilst they found that sea-ice has a profound influence on population levels of snow petrels, Ad?e and emperor penguins, the history of human exploitation in the Southern Ocean surrounding Antarctica, coupled with variation in sea-ice conditions between years, presents a picture too complex to form a firm conclusion at present.
The three Antarctic seabird species studied are known to be dependent on sea ice and do respond to changing conditions. It appears that all three species do better when sea ice is more extensive but each species may respond differently to changes in sea ice at different times in their breeding cycle - for instance adult Ad?es do well in years with extensive winter sea ice but chick survival is poor in years when summer sea ice is extensive.
Lead author Professor John Croxall said, ?The Antarctic marine ecosystem, far from providing an example of a pristine and undisturbed environment, has a history of human exploitation that has greatly influenced population size and behaviour of Antarctic species. Over the last two centuries hunting virtually eliminated Antarctic fur seals, reduced penguin numbers at various sites, devastated many great whale species, and caused the collapse of several fish species and stocks. This history of commercial exploitation, together with the as yet unknown impacts of this on future ecosystem stability, make detection of biological change difficult. Furthermore, the relationship between ice extent and seabird populations is complex and it is therefore not straightforward to predict how populations might change in the future?.
Issued by British Antarctic Survey Press Office.
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NOTES FOR EDITORS
Environmental Change and Antarctic Seabird Populations by John P Croxall, Phil N Trathan & Eugene J Murphy is published this week in Science
. Full copies of the paper are available for journalists via firstname.lastname@example.org - Tel:001 202 326 6440; 001 202 789 0455.
British Antarctic Survey is responsible for the UK?s research in Antarctica. It is a component of the Natural Environment Research Council. More information about the work of the Survey can be found on our website: www.antarctica.ac.uk
Photographs and video footage of seabirds are available from the BAS Press Office - Photographs are also available for download from HERE
Sea ice and climate:
The polar regions are an important part of the Earth's system. The presence of ice makes the climate of the polar regions particularly sensitive to warming by introducing a strong "feedback" mechanism. The extent of winter sea ice around Antarctica is thought to be a very sensitive indicator of climatic change but it has only been possible to observe this since suitable instruments were deployed on satellites in the early 1970s. In recent years, reducing sea ice extent in some regions has been balanced by increasing extent in others and there is no evidence for a decline in overall Antarctic sea ice extent. Antarctic temperature and sea-ice records show a high level of variability between years that makes the determination of trends from short records problematical.
The authors review the best long-term data for three high-latitude Antarctic seabirds ? Ad?e (Pygoscelis adeliae) and Emperor (Aptenodytes forsteri) penguins and snow petrel (Pagodroma nivea), which, together with their main prey, have largely escaped exploitation and thus potentially provide the best biological signals available. These species show several common patterns, which indicate that changes in sea-ice extent can have a profound influence on seabird populations. However, identifying causes and predicting future changes is complicated by inconsistencies between species and areas, and effects that are in opposite directions at different stages of the breeding or life cycle.
The Southern Ocean that surrounds Antarctica is rich in wildlife. Over the last two centuries hunting for whales and seals and fishing activity changed the balance of the ?ecosystem?. The collapse of whaling and fisheries has highlighted the lack of applied science strategy for management practice.
The small shrimp-like crustacean, krill is central to the Antarctic food web. When commercial krill fishing began in the mid-1970s, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) was formed to regulate exploitation of the Southern Ocean as an ecological unit. BAS marine research programmes provide data to underpin the UK commitment to the CCAMLR Convention.
Find out more about British Antarctic Survey studies on climate change and the exploitation of the Southern Ocean on: www.antarctica.ac.uk/Key_Topics/