Arctic species under threat, report warns

Polar bears clinging to melting ice sheets have become one of the most frequently used images to portray the perils of climate change.

But a new report by the U.S. Center for Biological Diversity (CBD) and UK-based Care for the Wild International (CWI) is bringing attention to the predicament of other equally endangered Arctic species.

Seventeen Arctic animals are highlighted in "Extinction: It's Not Just for Polar Bears."

Shaye Wolf, lead author and climate science director of the CBD told CNN: "The plight of the polar bear due to global warming is very well known and familiar. But many other Arctic species are suffering a similar fate -- from plankton all the way to the great whales." (Right: narwhale)

The impacts of climate change are "unfolding far more rapidly in the Arctic than any other area on the planet" threatening its ecosystem, the report said.

A 2009 study by Donald K. Perovich and Jacqueline A Richter-Menge -- "Loss of Sea Ice in the Arctic" -- reported that the sea ice extent in 2007 was one million square miles below the average figure recorded between 1979 and 2000.

This, and other data suggests, say scientists, that summer sea ice could completely disappear in the Arctic by 2030.

The ice retreat is already spelling trouble for marine mammals like the Pacific walrus and the harp seal.

Pacific walruses, (right) like many of the mammals in the report, are sea ice dependent says Wolf, with many having already suffering population declines.

"As we speak, there are 10 to 20,000 walruses holed up on Alaskan Arctic coastline. And that is attributable to sea ice loss," Wolf says.

"Walruses need sea ice for resting because they can't swim continuously. When they lose that sea ice, especially moms and calves, they are forced to come to shore -- where calves are very vulnerable to be trampled in stampedes."

Last year, Wolf says the stampede claimed 131 young walruses.

The number was even higher off the Russian coast in 2007 where several thousand calves died when around 40,000 walruses were pushed ashore.

Ocean acidification -- caused by increased uptake of carbon dioxide -- is happening more quickly in the Arctic than in warmer waters, says Wolf.

Shell-building marine creatures like the sea butterfly (Clione limacina) are particularly vulnerable to acidification. (Right: sea butterfly)

Their loss would be potentially devastating for other species.

On land, the Arctic fox -- found on the southern edges of the Arctic tundra -- is facing "myriad threats from climate change," including shrinking sea ice and tundra, declines in lemming prey and increased competition from the larger, more dominant red fox -- which is edging north as temperatures rise.

All the animals in the report are at risk of extinction due to climate change says Wolf.

"What is going on in the Arctic isn't something that we can consider completely remote from ourselves. Actually, it's a fantastic barometer of what is going to happen in the rest of the world," CWI's Rebecca Taylor told CNN.

"The Arctic is ground zero for climate change and we're already pushing many species towards extinction. The key to preventing their loss is reducing our greenhouse gas emissions -- specifically carbon dioxide -- to a level of 350ppm or below. That is a level many leading scientists have called for to restore Arctic sea ice," Wolf said.

Source:
Cable Network News, "Arctic species under threat, report warns", accessed September 14, 2010

Climate change threatens slow swimming narwhals

Narwhals are the 'marathon runners' of the oceans, scientists have discovered.

The Arctic-living tusked whales are exceptional endurance athletes, possessing a greater density of slow-twitch fibers in their muscles than any other marine mammal studied.

This ability also means that narwhales are one of the sea's slowest swimmers. That places them at high risk from climate change, as narwhals will not be able to cope with shifting, highly mobile ice floes caused by warmer seas. The highly mobile ice makes icebergs that are too big for these animals to swim beneath, and changes the reliability of known breathing holes.

Details of the narwhal's extreme endurance ability and susceptibility to climate change are published in the journal Marine Mammal Science.

Narwhals are one of three species of cetacean living in the Arctic, alongside the beluga whale and bow-head whale.

They are also known as the 'unicorns of the sea' due to their long, elongated tusks.

However, narwhals now have a new claim to fame, as the 'marathon runners' of the oceans, say researchers Professor Terrie Williams and Dr Shawn Noren of the University of California, Santa Cruz and Dr Mike Glenn, of Sea World, San Diego, US.

They made the first study of the physiological capacity of narwhals and found that the cetaceans have the highest levels of myoglobin in their muscles of any marine mammal measured to date. High levels of myoglobin allow large amounts of oxygen to be stored.

Narwhals also have the highest percentage of slow twitch muscle fibers within swimming muscles for any marine mammal, the researchers discovered. In narwhals, around 87% of their swimming muscle fibers are of the slow twitch variety, which respond slowly but do not tire easily.

Narwhals actually have a muscle composition close to that of human endurance runners, as the leg muscles of an elite marathon runner contain more than 90% slow twitch muscle fibers.

"This specialized morphology makes them excellent divers," Prof Williams stated, as their muscles can store and efficiently use large amounts of oxygen.

"But it comes at a cost. They appear to be one of the slowest swimmers out there."

Climate threat

This highly specialized swimming behavior puts narwhals at significant risk from the effects of climate change, warn the researchers.

Listed as 'near-threatened to vulnerable' on the IUCN list of endangered animals, around 75,000 narwhals are thought to survive, inhabiting the ice-choked waters of the Canadian Arctic and Greenland.

This means narwhals have to be able to predict where holes in the ice are, in order to reach the surface to breathe.

In fact, Prof William's study reveals that narwhals swim so slowly that they can only cover a distance of around 1.4km in any direction before they run out of oxygen, despite their endurance capability. So to survive, they need to be able to find a break in the ice at least every 1.4km.

"The big surprise is how little of the Arctic waters narwhals can use due to the limitation of breathing," says Prof Williams.

Worse, climate change will reduce the amount of suitable ocean, further endangering the species.

"Warmer temperatures are creating more icebergs and larger floes," says Prof Williams. "The problem is not the ice is disappearing, rather in the course of disappearing the ice has become highly mobile. That makes icebergs that are too big for these animals to swim beneath, and changes the reliability of known breathing holes."

The researchers estimate that just 10% of the water under larger ice floes contains enough breathing holes, or fish to hunt, to be suitable for narwhals. Shifting winds can also quickly move ice around, making the appearance of breathing holes even more unpredictable.

"A wrong decision [taken by a narwhal] or a shifting wind moving ice could be fatal."

Source:
BBC, "Climate change threatens slow swimming narwhals", accessed September 9, 2010