Seals face starvation as krill disappears
By Charles Arthur
4th November 2004
Scientists fear that global warming has led to a dramatic decline in stocks of krill, which is a key food for Antarctic seals, whales and penguins. New data shows krill numbers have fallen by about 80 per cent since the 1970s.
Researchers at the British Antarctic Survey (BAS) say more work is needed "urgently" to find out what the falling numbers of the shrimp-like crustacean could mean for the larger animals which feed on it.
Angus Atkinson, a marine biologist for the BAS, reports in this week's issue of Nature that while the overall effect of the decline was unclear, earlier studies suggested that penguins' diet, hunting behaviour and population sizes could be affected.
Statistical examination suggests the reason for the decline is a reduction in the amount of winter sea ice in an area north-east of the Antarctic peninsula - just below the southern tip of South America - where the krill population is concentrated. Krill feed on algae found on the ice: without it they starve. And it is that area which has displayed a strong warming trend over the past 50 years - although Dr Atkinson said the connection to the loss of sea ice, and the precise cause of the local warming, are not known.
The team compared data from 12,000 net hauls taken between 1926 and 1939 and 1976 and 2003. Eileen Hofmann, a professor of oceanography at Old Dominion University in Norfolk, Virginia, said further work was needed to establish if climate change was affecting marine food in the Antarctic Peninsula and its impact on penguins, seals and whales.