The Wave of the Future?

A monster sea wave might have whacked North America’s East Coast in prehistoric times. Could it happen again?

You’ve just a heart-stopping ride on the Tidal Wave, the beachfront roller coaster in Ocean City, Md. You’re feeling washed out but elated. Suddenly, a 30-foot wall of water crashes over the boardwalk, toppling the roller coaster like toothpicks and sending people flying. What is this? Another coastal thrill ride?

No, it’s a tsunami (soo-NAH-mee), a monster wave caused by a violent geologic disturbance, such as an earthquake, underwater landslide, volcanic eruption, or even an asteroid impact. Tsunamis almost always happen in the Pacific Ocean. But new scientific evidence suggests that a killer wave could one day swamp the Atlantic coast of the United States.

WHAT A CREEP

A team of scientists investigating the seafloor off Virginia and North Carolina has found evidence that the continental shelf might be weakening there. A continental shelf is a gently sloping area of seabed between the edge of a continent and the deep ocean. Last summer, the scientists discovered several large blowout features, or craters, where gas from beneath the seafloor had escaped.

Some of the craters are “quite large,” said team leader Neal Driscoll of Woods Hole Oceanographic Institution in Massachusetts. The four largest craters are, on average, 50 meters (164 feet) deep, 4 kilometers (2.5 miles) long, and 1 kilometer (0.6 miles) wide. A crater that size could easily swallow New York City’s Central Park!

Driscoll’s team is still trying to find out where the gas came from and how it escaped through the seafloor. Team member Jeffrey Weissel, senior scientist at Columbia University’s Lamont-Doherty Earth Observatory, explained that gas is always moving up through the layers of sediment on the ocean bottom. Those layers of sediment usually block gas from reaching the seafloor. However, in several places along the mid-Atlantic coast, the gas somehow penetrated all the layers and blew through the seafloor.

Creeping might have caused that gas to blow. Creeping is the sliding of layered sediments down a continental slope, like a carpet sliding down stairs. As the layers creep down a slope, they stretch and deform, opening avenues for underground gas to escape. “That’s why these [blowout] features are so close to the shelf edge,” Weissel explained.

COASTAL TERRORS

Weissel worries that the gas blowouts could be weakening the edge of the continental shelf. If the shelf were to cave, it could set off an underwater landslide large enough to trigger a tsunami.

A boat cruising directly above such a landslide probably wouldn’t detect the wake of the resulting tsunami amid normal wind waves and swell. That’s because as a tsunami moves from its source to the closest coast, its length can be as much as 100 miles and its height just a few feet. Only when a tsunami nears land does it become monstrous. In shallow water, it bunches up and gains height. Coming ashore, it pummels unsuspecting coastal areas with devastating force.

Tsunamis often catch coast dwellers by surprise. Moving at speeds of up to 965 kilometers (600 miles) per hour, they frequently arrive before people know they’re coming.

ATLANTIC MONSTER

Most of the areas that have felt the punch of a tsunami are located in and along the Pacific Ocean. Surrounding the Pacific is a band of volcanoes, mountain chains, and earthquake zones. This Ring of Fire is the most geologically active area on the planet.

On average, two destructive tsunamis occur every year in the Pacific Ocean. Alaska, Hawaii, California, Oregon, and Washington are the states most vulnerable to the monster waves. However, other states might be vulnerable too. There are indications that a tsunami may have hit the East Coast of the United States at least once–and one might strike again.

Along the southern end of the region where Weissel, Driscoll, and their team found the seafloor dotted with craters, they also uncovered features of a past underwater landslide. That landslide likely happened 20,000 years ago, at the peak of the last Ice Age, and could have spawned a tsunami that walloped the East Coast of the United States.

“A big landslide, the size of the one that occurred [during] the last Ice Age, could affect a large amount of the East Coast from Cape Hatteras, N.C., to Long Island, N.Y.,” Weissel said.

The possibility of such a wave striking again is rare, but real, both Weissel and Driscoll stressed. Their team plans to continue mapping the seafloor and keeping a watchful eye on areas vulnerable to underwater landslides. If a tsunami ever does hit the eastern seaboard, the last place you’ll want to be is on the Tidal Wave coaster.

A young Canadian is trying to save a mysterious native bear from disappearing

If you ever happen to meet Simon Jackson, be prepared for a passionate lesson on a mysterious white animal that lives only in the Canadian province of British Columbia. The 18-year-old B.C. native is on a crusade to save that animal, known locally as the spirit bear.

The dual threats of logging and hunting in the old-growth forests where the unusual white bear lives have made its future uncertain. Jackson’s nonprofit organization, The Spirit Bear Youth Coalition, and several environmental groups are urging the B.C. government to create a sanctuary, or place of refuge, for the bears.

“I was really struck by this incredible creature,” Jackson said. “And I wanted other people to have a chance to see it. It’s the panda of Canada–equally as beautiful and equally as rare.”

BEAR FACTS

As many as 400 spirit bears roam the forests of coastal British Columbia. Though rare, the spirit bear is not an endangered species. In fact, it’s not a species at all. It belongs to a subspecies, or group within a species that has unique characteristics. The spirit bear is a white-colored Kermode bear, a subspecies of black bear that lives in the rain-soaked forests of coastal B.C. The smaller skull size of the Kermode bear qualifies it as a subspecies.

Most Kermode bears are black, but on a cluster of small coastal islands, one in every ten is white. Scientists are still trying to figure out the genetic, or hereditary, process that makes a normally black Kermode bear white. (See “White Wonder.”)

FAIR GAME

Of all the black bears living in North America, only a few populations are protected from hunters. White Kermode bears are one such group. Black Kermode bears are fair game, however, and that’s a concern to conservationists, who worry that black Kermodes might carry the gene (or genes) for white fur. Genes are units of heredity that hold the instructions for every cell in the body.

Conservationists are also worried about logging in the spirit bear’s habitat. Consumer pressure has forced logging companies to verbally agree not to cut trees in those forests. No legal agreement exists, however. Environmental groups fear that the spirit bear’s habitat is still in danger.

PROTECTION NEEDED

Though the chainsaws are idle, Wayne McCrory, a biologist with the Valhalla Wilderness Society, is fervently trying to persuade government officials that more protection is needed. McCrory has proposed that 250,000 hectares (620,000 acres) of island and mainland old-growth forest be deemed a sanctuary for spirit bears and other threatened wildlife.

According to McCrory and Jackson, logging even a fraction of that land could deplete the habitat of salmon, which is a crucial food source for bears. Logging could also reduce bear denning sites and expose white spirit bear cubs to predators such as grizzly bears. In time, spirit bears could vanish from the British Columbia coast.

“This is their last intact habitat,” Jackson said. “If spirit bears disappear, we can never get them back.”

WHITE WONDER

The Tsimshian Indians of British Columbia call the spirit bear mokgm’ol–“the white bear put on the planet to remind people of a time when ice covered the land.” What do scientists say about the origins of the white bear?

Most scientists agree that the spirit bear is not an albino bear. Albinism is an inherited condition characterized by the absence of a certain pigment (coloring agent) in the eyes, skin, hair, scales, or feathers. That pigment is called melanin.

Albino animals rarely survive in the wild because their white coloration stands out, making them more vulnerable to predators. A shortage of melanin also causes albinos to have vision and hearing problems.

Because white bear cubs are frequently sighted with black parents and siblings on the B.C. coast, most scientists favor the idea that spirit bears get their white fur through a phenomenon called recessive inheritance. Black bears inherit one allele, or gene for a specific trait, in this case fur color, from each parent. The allele for black fur is a dominant allele. The allele for white fur is a recessive allele. When a bear inherits two dominant alleles, or a dominant and a recessive allele for fur color, the bear will be black. Only when a bear inherits two recessive alleles for fur color will it be white.

A spirit bear is thought to be a black Kermode bear that has inherited a recessive allele for fur color from both its father and its mother.

The Batman Of Belize

As I stood under a thatched roof in the middle of a Central American rain forest, zoologist Bruce Miller approached from the evening shadows with something wriggling in his cupped hands. “This,” he said, “is the smallest bat in Belize–a black-eared yellow bat.”

Miller gently stretched the bat’s wing so I could see that it had a wrist, a thumb, and four long, needle like fingers. The fur of this flying mammal was incredibly soft. I once thought bats were scary, but this one was cute.

I was in Central America for a few days last spring to learn about the pioneering research Miller and his wife, Carolyn, are doing. The Millers first landed in Belize more than 14 years ago intending to study nothing but birds. Gradually, their interests expanded to include mammals. Now Carolyn spends her mornings scouring the ground for the tracks of jaguars, and Bruce spends his nights combing the sky for bats.

DETECTING BATS

On most nights, Miller doesn’t see or hold the bats he studies. Instead, he waves a small yellow and white box, called an Anabat detector, above his head. The Anabat detector functions as an electronic ear, picking up inaudible bat sounds.

Bats use echolocation to navigate. They produce high-frequency sounds that echo off surrounding objects. The echoes enable the bats to detect trees in their path or the tiny insects they eat.

When the Anabat is plugged into a laptop computer equipped with special software, bat voices become squiggles, dots, and lines on the laptop’s screen. Each distinctive pattern and shape, known as a vocal signature, represents the unique sound waves emitted by a particular species of bat.

LEAF-NOSED BATS

Some bats found in Belize, called leaf-nosed bats, don’t echolocate; they find their way with old-fashioned eyesight. Bat researchers have been studying leaf-nosed bats for more than 30 years. Like birds, leaf-nosed bats are easily caught in invisible nylon nets.

Until recently, not much was known about the other families of bats in Belize. “These bats use echolocation, allowing them to `see’ nets like a big wall in their path and say, `I don’t want to go there,'” Miller told me.

FACES AND VOICES

Imagine the excitement when Miller received his first Anabat detector five years ago. “We turned the Anabat on and immediately `heard’ bats,” Miller said. “Then we hooked it up to the computer and saw five or six different shapes of signals.”

Then came the work of deciphering the signals. “Initially everything was an unknown” Miller said. “We started naming [the species] Unknown 1. Unknown 2, Unknown 3….” To match faces to the signals, the Millers had to catch some bats and fly them in their “sound lab”–their kitchen.

“We just let them fly laps around the kitchen and made recordings with the Anabat.” said Miller. “After we had enough, we opened the sliding door, and on their next lap, they went right out.”

So far, Miller has identified the vocal signatures of 28 of the 33 echolocating bat species known to live in Belize. “Everywhere we go, we find species of bats we just never knew were there before,” he said. By storing the data on his computer, Miller is well on the way to his next goal: developing regional bat project to determine which habitats are crucial for the bats’ survival.

“If we lose the bats, we’re going to lose the tropical forest.” he said. “In the tropics, the birds are the day crew, and the bats are the night crew.” Everything that birds do during the day–from pollinating plants to transferring seeds to eating insects that gobble plants–the bats do at night. “It keeps the tropical system going,” he added.

BAT MYTHS

Though bats are key players in the maintenance of the tropical forest, many species are on the decline. “A lot of people assume all bats are [bloodsucking] vampire bats and that they’re bad.” Miller said. “So people kill them.”

In reality, only three species of vampire bat exist. Two are extremely rare and only feed on birds. The third wasn’t common until humans began converting forests to fields populated by cows. Sucking blood from wild animals that move around a lot is difficult for vampire bats and keeps their numbers low. But with cows and other domestic animals, the vampire bats can just fly right up to an easy 20-minute meal. As a result, their numbers have swelled.

Labeled as pests, vampire bats are often burned out of their caves. But caves are like apartment buildings: All kinds of bats, not just vampire bats, reside in them. When caves are burned. everything in them, including other bats, are killed.

“Bats perform a really valuable role,” said Miller. “But because it’s in the dark, it’s like `out of sight, out of mind.’ The average person just doesn’t know about them.”