Penguins suffer as Antarctic krill declines
Published: 12th Apr 2011 07:42:57
A number of penguin species found in western Antarctica are declining as a result of a fall in the availability of krill, a study has suggested.
Researchers, examining 30 years of data, said chinstrap and Adelie penguin numbers had been falling since 1986.
Warming waters, less sea-ice cover and more whale and seal numbers was cited as reducing the abundance of krill, the main food source for the penguins.
The findings appear in the Proceedings of the National Academy of Sciences.
Antarctic krill (Euphausia superba) is a shrimp-like creature that reach lengths of about 6cm (2in) and is considered to be one of the most abundant species on the planet, being found in densities of up to 30,000 creatures in a cubic-metre of seawater.
It is also one of the key species in the ecosystems in and around Antarctica, as it is the dominant prey of nearly all vertebrates in the region, including chinstrap and Adelie penguins.
Warming to change
In their paper, a US team of scientists from the National Oceanic and Atmospheric Administration (Noaa) and the Scripps Institution of Oceanography said a number of factors were combining to change the shape of the area's environment.
"The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly [wiped out] by humans," they wrote.
"This region is also among the fastest warming areas on the planet, with 5-6C increases in mean winter air temperatures and associated decreases in winter sea-ice cover."
They added that analysis of data gathered during 30 years of field studies, and recent penguin surveys, challenged a leading scientific idea, known as the "sea-ice hypothesis", about how the region's ecosystems was changing.
"(It) proposes that reductions in winter sea-ice have led directly to declines in 'ice-loving' species by decreasing their winter habitat, while populations of 'ice-avoiding' species have increased," they explained.
However, they said that there findings showed that since the mid 1980s there had been a decline in both ice-loving Adelies (Pygoscelis adeliae) and ice-avoiding chinstraps (Pygoscelis antarctica), with both populations falling by up to 50%.
As a result, the researchers favoured a "more robust" hypothesis that penguin population numbers were linked to changes in the abundance of their main food source, krill.
"Linking trends in penguin abundance with trends in krill biomass explains why populations of Adelie and chinstrap penguins increased after competitors (fur seals, baleen whales and some fish) were nearly extirpated in the 19th to mid-20th Centuries, and currently are decreasing in response to climate change," they wrote.
The team said that it was estimated that there was in the region of 150 million tonnes of krill for predators after the global hunting era depleted the world's whale population.
During this period, data shows that there was a five-fold increase in chinstrap and Adelie numbers at breeding sites from the 1930s to the 1970s, they reported.
"The large populations of Adelie and chinstrap penguins were not sustained for long, however, and are now declining precipitously."
They added that this was happening as rising temperatures and decreases in sea-ice was altering the physical conditions required to sustain large krill populations.
"We hypothesise that the amount of krill available to penguins has declined because of the increased competition from recovering whale and fur seal populations, and from bottom-up, climate-driven changes that have altered this ecosystem significantly during the past two to three decades."
The US researchers concluded that the penguin numbers and krill abundance were likely to fall further if the warming trend in the region continued.
They wrote: "These conditions are particularly critical for chinstrap penguins because this species breeds almost exclusively in the WAP and Scotia Sea, where they have sustained declines in excess of 50% throughout their breeding range."
At 21:02:14 in SportLouis Smith marked his international comeback by helping England take a commanding lead at the midway stage of the gymnastics team finals.
At 20:49:37 in SportJersey's Zane Duquemin says he was disappointed to finish ninth in the final of the shot put at the 2014 Commonwealth Games in Glasgow.
At 20:37:39 in SportEngland have had two very good days in the third Test against India in Southampton.
At 20:35:48 in SportEngland batsman Ian Bell dedicated his return to form to the memory of his grandfather William, who died earlier this month.
At 20:30:50 in WorldVeterans affairs leaders in Congress have announced a compromise to help address the problems overwhelming the US veterans healthcare system.
At 20:23:36 in HeadlinesWhether it's a curled lip or a keen cheekbone, we all make quick social judgements based on strangers' faces.
At 20:20:10 in EnglandTwo poultry factories alleged to have committed hygiene breaches have been rated as "good" and "satisfactory" by the Food Standards Agency (FSA).
At 20:18:32 in SportEngland's Ollie Hynd completed a clean sweep of titles with a superb victory in the SM8 200m individual medley.
At 20:17:17 in SportEngland have defended Moeen Ali for wearing wristbands showing support for Gaza during the third Test with India.
At 20:13:16 in SportEngland's Adam Gemili is into the men's 100m final after running the second fastest semi-final time.
Harvard CitationBBC News, 2011. Penguins suffer as Antarctic krill declines [Online] (Updated 12th Apr 2011)
Available at: http://www.ukwirednews.com/news/145269/Penguins-suffer-as-Antarctic-krill-declines [Accessed 28th Jul 2014]
News In Other Categories
Veterans affairs leaders in Congress have announced a compromise to help address the problems overwhelming the US veterans healthcare system.
Tory MP David Ruffley is to retire from Parliament at the next election.
With the doors to its brand new £1million training centre officially open, one of the UK's leading apprentice training providers, Bristol based S&B Automotive Academy, is showcasing its world-class facilities by launching a series of foreign student exchanges for the first time in its 41-year history. To get a flavour of what life is like as an apprentice in the UK, the Academy hosted 16 apprentice engineers and bus drivers from the G9 Automotive College in Hamburg, Germany, as part of a Europe-wide vocational training initiative called the ‘Leonardo Programme’ with support from the European Social Fund. In a reciprocal arrangement, S&B will be sending nine apprentices to Germany during February 2012 so that they can get an appreciation of life in the automotive industry on the Continent. A further three German exchange groups are being planned for next year. Designed to assist the development of vocational skills and training across Europe, including work placements for trainees, the Leonardo Programme has a budget of €1.75bn, which is helping to encourage UK organisations to work with their counterparts abroad. In what is expected to be another challenging year for employers in the UK automotive sector, S&B’s Chief Executive, Jon Winter, claims that the exchange initiative will bring many benefits to the Academy and its apprentices: “In a world of global automotive brands, it’s important for our learners to understand the international context of the industry they have chosen to make their career. This new exchange programme will enable apprentices and Academy staff alike to achieve a better understanding of the challenges and opportunities within the automotive arena in Europe. With the Academy’s influence also extending to the USA and Asia, there’s every possibility that this initiative could move further afield in the future.” Continued Winter: “The need for skilled technicians across the world is on the increase and we actively encourage our apprentices to look at broader horizons during their training. Many of them have already learned the phrase ‘Vorsprung durch Gelehrtheit’, quite simply, ‘Advancement through learning.” In the 2010/11 academic year, S&B doubled the number of successful Apprenticeships over the previous year with some 350 apprentices graduating from the Academy. At the same time, achievement levels reached an all-time high with an overall success rate of 85%. For those learners on the Advanced Apprenticeship three-year programme, success rates were even higher, at over 98%. PHOTO CAPTION: As part of their exchange visit, S&B Automotive Academy arranged for the German apprentices to visit Hampshire bus operator, Bluestar, at its Barton Park depot. The students are pictured with S&B’s Andy West (3rd right) and Steve Prewett, Bluestar’s Area Engineering Manager (2nd right). Ends http://www.sandbaa.com
Russia has offered 3.9m roubles ($110,000; £65,000) in a contest seeking a way to crack the identities of users of the Tor network.
Unionists have called on the Sinn Fein mayor of Newry and Mourne District Council to apologise for urging shops not to sell goods from Israel.
A four-week strike in South Africa's mining industry has come to an end after the country's biggest trade union sealed a deal with employers.