Antarctic fur seals feel climate impacts

Changes in the Antarctic climate are showing up in the fur seal population, say scientists.

Over the study period, the birth weight of pups was seen to fall significantly

Three decades of data show the females of this species are being born smaller, and those that do survive to motherhood are breeding later in life.

Subtle changes in their genetics are also being recorded.

Researchers tell the journal Nature that a shift in a dominant climate pattern has affected the supply of the seals' primary food source - krill.

"There has been a significant reduction in the size and the mass of the pups at birth," explained Dr Jaume Forcada from the British Antarctic SURVEY (BAS).

Dr Iain Staniland from the British Antarctic SURVEY explains how warming seas are reducing the food supply for Antarctic seals

"Over 27 years, we see pups being born with 80% less body mass. We also see the females breeding later in age - at least by one or two years.

"And when they start breeding, they are bigger than they used to be 30 years ago. This kind of thing has been seen before in all sorts of mammals, and is classically an indication of food stress."

The fur seals gather in huge numbers on beaches of Bird Island and all around South Georgia

The study was centred on South Georgia, a British Overseas Territory (BOT) in the South Atlantic that falls within the influence of Antarctic waters.

BAS has a long-term monitoring station on the territory's Bird Island, from where it has tracked the behaviour and health of the furs since the early 1980s.

In their report, the researchers tie the declining performance of the population directly to the increasingly unreliable provision of krill.

In particularly bad years when there are few krill at South Georgia, all the predators that depend on them will suffer poor breeding success, and the beaches will be littered with dead pups and penguin chicks.

From BBC News Sci/Environment

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