Antarctic seabirds and climate change

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, Adélie 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 Adélies 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”.