The Heat Is On: Is climate change causing the arctic food chain to unravel?

By Sharon Oosthoek

(j) Remi Foubert-AIIen wanted to see killer whales for as long as he could remember. But he was

completely unprepared when they swam past his boat in Hudson Bay near his hometown of

Churchill, Manitoba.

"I can't believe I'm looking at orcas!" he shouted over the noise of his outboard motor. "Oh man, my

dad is going to be so jealous."

Foubert-AIIen-a zodiac driver with Sea North Tours-is understandably astonished. Killer whales in

Hudson Bay were unheard of until recently. European explorers who wrote of their adventures in the

area beginning in the early 1600s made no mention of the whales before 1900.

But between the turn of the last century and 1960, explorers and Inuit hunters living along the bay

began reporting the odd sighting-just a handful really. Since then, there has been a small but

steady increase, leading to a peak of 40 sightings in the last five years.

Steve Ferguson, a biologist with Fisheries and Ocean Canada, is among those trying to figure out

what it all means. His research shows climate change-in the form of declining summer sea ice in

the Hudson Strait-is likely responsible for killer whales from the Northwest Atlantic finding their way

into the bay. That's because the whales generally avoid ice. Their tall dorsal fins can get stuck as

they swim underneath_

@ But now that some killer whales are making Hudson Bay their summer home, scientists wonder what

it means for the food web. Stable isotope analysis of the teeth of two orcas found in the bay

suggests they are eating narwhals, belugas and bowheads. With little experience evading killer

whales, and no ice in which to hide, these marine creatures could be in trouble. To make matters

more complicated, both predator and prey are at-risk species in this part of the world. "We're not

confident these (prey] populations can adapt, " says Ferguson. "They're not likely to say, 'Let's move

out of Hudson Bay_ It's not a safe place anymore."'

The whales' presence in Hudson Bay is but one example of the proverbial canary in a coal mine. It

illustrates the complexity of climate change's impact in the far north, including Alaska. Across the

region, species are moving and interacting in brand new ways and causing the food web to unraveL

Certainly Alaska is heating up faster than anywhere else in the United States. Over the past 50

years, the northernmost state has seen some of the most rapid warming on Earth, with temperatures

Source: http://www.defenders.org/magazine/winter-2013/heat

rising 1 to almost 4 degrees Fahrenheit. As with Hudson Bay's killer whales, warming temperatures

mean an expanded range for some northwestern and Alaskan species, potentially putting others at

risk.

The U.S. Fish and Wildlife Service, for example, reports that the northward expansion of beavers

has blocked many traditional salmon-spawning streams. New research also suggests increased

competition between trumpeter swans and tundra swans-on whose territory the trumpeters are now

encroaching.

National Park Service biologist Joshua Schmidt, along with colleagues from the National Ocean and

Atmospheric Administration and the University of Alaska, analyzed trumpeter swan breeding range

data from 1968 to 2005. Their study, published in the journal Wildlife Biology in 2011 , found

trumpeters have expanded their ranges north as the number of above-freezing days at higher

latitudes has increased.

But because their smaller cousins, the tundra swans, already breed at these latitudes, the move

brings the two species into direct competition. Under the former climate regime, length of their

respective breeding seasons likely kept them apart-trumpeter swans require up to 45 more days

above freezing than do tundra swans. Scientists don't know yet whether the larger swan's presence

at higher latitudes is affecting populations of tundra swans, but Schmidt and his colleagues suggest

it could be bad news for the smaller birds.

@ A shift in breeding range also plagues Alaska's walruses. Walrus mothers off the northwest coast

usually stay with the Chukchi Sea ice as it retreats north for the summer. That's because there are

fewer predators on ice than on land, making it a good place to haul out to give birth and nurse their

young. And when it's time to eat, mothers can dive to the shallow ocean floor for clams.

"But the sea ice is retreating earlier and farther north into the Chukchi each summer," says Karla

Dutton, Defenders' Alaska director. In four out of the past five summers, it has disappeared from

above the clam-rich continental shelf and instead floats over the deep ocean where clams are few

and far between. When that happens, walruses abandon the summer sea ice, opting instead to haul

out on land, closer to their feeding grounds. But the consequences are proving deadly.

When walruses gather on chunks of sea ice they usually number 50 or fewer individuals. On land,

herds can reach into the tens of thousands. "So if there is any disturbance from humans or bears or

airplanes or boats, they will stampede to the water and trample calves," says United States

Geological Survey (USGS) marine biologist Chad Jay. In 2009, USGS scientists counted 130 dead

walruses-mostly calves-after one trampling incident off the northwest coast of Alaska.

@Walruses are too big to ignore when their behavior changes so dramatically, but it seems even the

tiniest northern organisms are feeling the heat. Scientists recently discovered thinner summer sea

Source: http://www.defenders.org/magazine/winter-2013/heat

ice in the Chukchi Sea is responsible for massive phytoplankton blooms, which form the base of the

Arctic food chain.

Writing in the journal Science last June, Stanford University marine scientist Kevin Arrigo and

colleagues showed that as the ice melts, it forms pools of water on top that concentrate sunlight

down below. The extra light triggers phytoplankton blooms, making these areas more productive.

The researchers now worry that an earlier Arctic spring may mean earlier sea ice melt and earlier

phytoplankton blooms. That could spell trouble for migrating marine animals that arrive looking for

food after the blooms' peak.

Of course, any change in environment has the potential to produce winners and losers, says

Brendan Kelly, assistant director for polar science in the Executive Office of the President

He points to humpback whales which are moving farther north to feed. "The increased access to

formerly inaccessible waters likely will benefit their populations," says Kelly. "On the other hand, the

potential impact on bowhead whales competing with humpbacks might be a net negative for the

bowheads."

@A warming north is also making for some strange cross-species bedfellows.

In 2010, Kelly was part of a group of wildlife experts who sounded an alarm about the suspected link

between rising temperatures and the hybridization of northern wildlife. Writing in the journal Nature,

Kelly and his co-authors pointed to grizzly-polar bear hybrids in Canada's north, suggesting they are

a sign of Arctic biodiversity at risk. They argue governments must manage hybrids before

interbreeding leads to the extinction of rare species.

In April 2006, Idaho hunter Jim Martell shot the first genetically confirmed "grizzlar" in the Northwest

Territories. Martell thought he'd shot a polar bear, but when he and his Inuit guide, Roger Kuptana,

got closer they discovered the creature had unusual features. Its white fur was mottled with brown

patches, and thin circles of black skin rimmed its eyes. It also sported the grizzly's distinctive long

claws and humped back.

British Columbia-based wildlife geneticist David Paetkau, whose company tested the hybrid's DNA,

muses that warming temperatures may be causing shorter hibernation periods for grizzlies. With

more time on their paws, grizzly males may now be wandering north, where they're mating with polar

bears. Several other grizzlars have since been spotted in Canada's north and it's possible they exist

in Alaska, too.

Meanwhile, Kelly suggests the resulting hybrids may have a leg up initially, but that each mixing of

species could bring bad news in terms of their ability to adapt The genetic gamble certainly had

mixed results for polar-grizzly hybrids in a German zoo. They were good at hunting seals, but didn't

have the strong swimming abilities of their polar bear forebears.

Source: http://www.defenders.org/magazine/winter-2013/heat

"In a first generation you retain most of the good qualities of each of your parent species," says

Kelly. "But over time, you will break up those combinations more and more. You'll get more

maladaptive combinations. So the good news [for the hybrid bear] is, 'I've got these great sealing

abilities, the bad news is that I really can't swim."'

This impacts more than just the polar bear. "If hybrid polar bears lose their ability to stalk and kill

ringed and bearded seals, their primary prey, species like arctic fox will be in dire straits as they rely

on polar bears to provide the bulk of their winter diet from the remains of seals killed for their

blubber," adds Defenders' Dutton.

@Of course bears are not the only animals capable of crossbreeding under warming conditions.

Rapidly disappearing sea ice means the barrier that once kept Arctic species apart is literally melting

away. Kelly and his co-authors also point to an apparent bowhead-right whale photographed in the

Bering Sea in 2009, a suspected narwhal-beluga found west of Greenland in the late 1980s, as well

as various confirmed hybrid porpoises and seals.

University of Alaska marine biologist and co-author, David Tallman says that while it's unlikely

hybridization is widespread in the Arctic, no one has looked systemically at the issue.

"It's likely to become increasingly important as the summer ice diminishes and is ultimately lost,"

says Tallman. "Hybridization is essentially impossible to reverse once it has begun on a large scale.

So, we want to be sure to halt any hybridization before it becomes unmanageable and unique

lineages are lost forever."

While the situation for some northern species may be dire, good science is crucial when finding

solutions, researchers point out. That's why Defenders of Wildlife helped launch USGS's Climate

Change and Wildlife Center and lobbies to keep it funded every year. With the opening of a new

office in Alaska, scientists will be able to focus on northern species.

Defenders is also championing the development of The National Fish, Wildlife and Plants Climate

Adaptation Strategy. It represents an unprecedented cooperative effort among federal, state and

tribal partners to put forth a plan to safeguard fish, wildlife, plants and the natural systems on which

they depend.

In the meantime, it's important to know that there will in fact be successful adaptations to climate

change, says Kelly. The key though is that the ability to adapt is all about the pace of change.

"Changes that happen over one or a few generations are more likely to lead to population reductions

and extinctions than will slower changes that span more generations," says Kelly. "It is not too late to

reduce emissions of greenhouse gases that are driving changes in the Arctic ecosystem."

Toronto journalist Sharon Oosthoek's story about black-footed ferrets and prairie dogs ran in the

winter 2011 issue of Defenders.

Source: http:Uwww.defenders.org/magazine/winter-2013/heat