Warming Waters Threaten 'Unicorns of the Sea'
ANDREA SEABROOK, host:
Now to a challenge to creatures dealing with another kind of natural challenge. They're called Narwhals. It's a type of whale known for the tusk that spirals out of its head. That tusk is actually a giant tooth. Narwhals live in the arctic along with a better publicized creature in crisis, the polar bear.
This week the Bush administration faces a deadline on whether to add the polar bear to the endangered species list. A new report says the Narwhal is in even bigger trouble. NPR's John Nielsen has more.
JOHN NIELSEN: Narwhals, known to many as the unicorns of the sea, can be extremely hard to find. But sometimes you get lucky, says researcher Kristin Laidre of the University of Washington. Not too long ago, she watched in awe as several thousand Narwhals passed the edge of an ice flow west of Greenland, raising and then lowering their legendary tusks.
Ms. KRISTIN LAIDRE (Researcher, University of Washington): It's quite fantastic when you have that many animals that close to you, not only what you see but also what you hear. Because the sound of a whale taking a breath is actually very intense and very loud. And when you have lots and lots of whales around you, coming up for air it's sort of its own version of a symphony or an orchestra.
NIELSEN: Unfortunately, Laidre says, changes linked to global warming could end those symphonies for good. She reached that conclusion in a study that ranked the narwhal as the marine mammal least likely to survive melting ice flows and other changes linked to warmer temperatures. That study asks some crucial questions about whales, seals, polar bears and walruses found above the arctic circle.
Ms. LAIDRE: For example, how big is the population size or how big is their geographic range? Do they only feed on, you know, a few species and the same species all the time or are they generalists in the sense that they'll eat whatever comes in front of them.
NIELSEN: Laidre says the answers to those questions helped her quantify the climate change strengths and weaknesses of the mammals in her study, which was published in the journal Ecological Applications. She says ring seals and arctic seals turned out to be the species most likely to succeed because they have a lot of strengths. They're widespread, they're abundant then they're capable of eating a huge range of underwater creatures.
Less abundant animals, like bowhead whales, received slightly lower rankings. Then there were the walruses. They were much more difficult to rank because different populations of walruses appear to have very different lifestyles. For example, walruses that live on the Pacific Coast cannot survive without an ice flow.
Ms. LAIDRE: Whereas in the Atlantic, it's not quite the same. The walrus, of course, do use the ice but they also use the land. And that makes them less sensitive in the Atlantic but more sensitive in the Pacific.
NIELSEN: Polar bears and narwhals brought up the rear in terms of their sensitivity to climate change. Laidre says that's because both species need sea ice to survive. Polar bears hunt for seals on top of the sea ice, while narwhals dive down underneath it to get a fish like halibut.
Laidre says the polar bears may have one major advantage over the narwhals when it comes to coping with climate change, however. They are found almost everywhere in the arctic, which raises the odds that at least some of them will survive the coming changes.
Narwhals, on the other hand, live almost exclusively in isolated waters off Canada and Greenland. In other words, if something bad happens in those waters, the narwhal may have trouble bouncing back.
Ms. LAIDRE: It goes to the same place year after year. It has a very specific migration, it has a very limited diet that doesn't reproduce very fast and relative to the other species we examined, it doesn't have a very large population size.
NIELSEN: Laidre says the problems of the narwhal are made worse by the fact that it could take 100 years to reverse global warming. By that time, the unicorns of the sea could be long gone, she says.
John Nielsen, NPR News, Washington.