Climate change threatens to make the antarctic fur seal extinct
Steve Connor
Steve Connor is the Science Editor of The Independent. He has won many awards for his journalism, including five-times winner of the prestigious British science writers’ award; the David Perlman Award of the American Geophysical Union; twice commended as specialist journalist of the year in the UK Press Awards; UK health journalist of the year and a special merit award of the European School of Oncology for his investigative journalism. He has a degree in zoology from the University of Oxford and has a special interest in genetics and medical science, human evolution and origins, climate change and the environment.
Science Editor
Wednesday 23 July 2014
Antarctic fur seals which were brought to the brink of extinction a century ago when they were ruthlessly hunted are now facing a new threat from food shortages caused by climate change, scientists have found.
The pressure on the population of fur seals in the South Atlantic is now so intense that it is even changing their genetic make-up according to a 20-year study that has discovered a link between the genetics of the fur seals and its main food source – Antarctic krill.
Scientists have found that female fur seals living on South Georgia Island with only a certain combination of genes are surviving long enough to breed and that these seals are breeding later in life and less frequently than seals in previous years with a different genetic constitution.
“Compared with 20 years ago, we can see that female fur seals are now born with a lower weight, those that survive and return to breed tend to be the bigger ones and they have their first pup later in life than they used to,” said Jaume Forcada of the British Antarctic Survey in Cambridge.
“Such changes are typically associated with food stress. An important food source for the seals is Antarctic krill. Decades of data collected at South Georgia show how changes to the seal population have occurred over time with changes in krill availability,” said Dr Forcada, lead author of the study published in the journal Nature.
Genetic testing has shown that female fur seals with a diverse combination of genes from both parents – known as heterozygosity – are surviving longer than females with a low level of genetic diversity, known as homozygosity.
Normally, heterozygosity is associated with evolutionary genetic fitness as individuals are better at surviving, but this is not longlasting as the trait results from the random recombination of genes and is not uniformly passed down the generations like other inherited traits, the scientists said.
Finding an increase in genetic heterozygosity might suggest that the seals are responding well to environmental pressures, but in fact the reverse is probably happening and is a worrying symptom of a population that is once again in decline, they said.
“We found that over the last two decades, the proportion of breeding females that are highly heterozygous has increased, as these individuals are more likely to survive the changing conditions,” said Joe Hoffman of Bielefeld University in Germany, the study’s coauthor.
“Strong selection by the environment can drive rapid evolution. However, in this case the seals do not appear to be evolving because surviving females do not pass their high heterozygosity on to their offspring,” Dr Hoffman said.
“With each new generation, the process of selection has to start all over again, with only those individuals that happen to be born more heterozygous having a good chance of survival. As the climate continues to change, many fur seal pups are not surviving to adulthood and the population is declining,” he said.
The availability of krill, a type of shrimp-like crustacean, is becoming more variable as a result of the changing climate in the region, such as warmer waters and melting ice. This is having a direct impact in the numbers of krill found within the fur seals’ hunting grounds, the scientists said.
“Our results provide compelling evidence that selection due to climate change is intensifying, with far-reaching consequences,” they concluded in their study.
Oxford zoologists Tim Coulson and Sonya Clegg warned in a commentary article that the findings suggest that it may be much harder to arrest the ongoing decline of the Antarctic fur seal in the 21st Century than it was in the last century.
Other species affected by climate change
As global temperatures increase in the coming decades, scientists expect the warming to have a significant impact on a wide variety of vulnerable species.
Alpine plants and amphibians such as frogs, toads and salamanders that live at high altitudes will be among the first to suffer. The golden toad of Costa Rica is believed to have gone extinct from its cloud forest habitat largely because of increasing temperatures.
Much of the impact on species is likely to result from a complex interaction of plants and animals, and changes to the timing of vital food sources, especially for the newly hatched chicks of vulnerable birds.
Studies have shown for instance that the food supply of the great tit, Parus major, now peaks earlier in the year but there has been no corresponding change to the time of the year that the tits lay their eggs, causing a mismatch between food supply and the timing of breeding.
One of the most visible effects of climate change in years to come will be the impact on coral reefs, which can be seen from space. Both increasing ocean temperatures and rising ocean acidity is likely to lead to a tipping point later this century when many reefs will begin to die off.
-
Malaysia Airlines MH17 crash: Vladimir Putin is given 'one last chance' to end hostilities in Ukraine
-
The 'scroungers’ fight back: The welfare claimants battling to alter stereotypes
-
The truth about conspiracy theories is that some require considering
-
Malaysia Airlines MH17 crash: Ukrainian military jet was flying close to passenger plane before it was shot down, says Russian officer
-
Malaysia Airlines MH17 crash: Massive rise in sale of British arms to Russia
-
Malaysia Airlines MH17 crash: victims’ bodies bundled in black bags and loaded onto trains
- 1 Malaysia Airlines MH17 crash: Pro-Russian rebel 'admits to shooting down plane'
- 2 Israel has discovered that it's no longer so easy to get away with murder in the age of social media
- 3 Israel-Gaza conflict: The myth of Hamas’s human shields
- 4 Amy Winehouse unpublished 2004 interview: ‘Ten years from now I’ll be 30, so I’ll maybe have one baby’
- 5 Dutch paedophile club to fight their ban at the European Court of Human Rights
Topman: Tips from top stylists
Shop London has teamed up with Topman. View the latest film clips shot at Topman Oxford Circus, plus your chance to win a £1,500 voucher.
Win a tailor-made trip to Graubünden, Switzerland’s No. 1 holiday destination
Discover Swiss alpine holidays – your way
The Gambia in the Summer
The Gambia may be the smallest country in mainland Africa but this is no reflection of it rich versatile offering.
#fashionhappy film competition
Calling all fashionistas! Enter our film competition to win a £2,000 Westfield Gift Card plus an internship at London Live.
Win a family FreeCycle weekend experience
This summer we’ve teamed up with Prudential to offer readers a brilliant opportunity to get the whole family together to experience the fun and freedom of cycling around a 10-mile traffic-free circuit in central London.
Update your holiday wardrobe
Update your holiday wardrobe with tropical prints, the perfect pair of sandals and some seriously stylish swimwear to make a splash in. Bon voyage.
Summer Sports Lux
From silk track pants to a swimsuit to make a splash in, this summer’s sport lux moment is certain to stretch your style credentials.
Get the look. See the trends.
Westfield and Snapfashion team up to create a new digital styling tool. Create a style board or browse this season's trends. #editme.
Enter the latest Independent competitions
Win anything from gadgets to five-star holidays on our competitions and offers page.
Business videos from commercial thought leaders
Watch the best in the business world give their insights into the world of business.