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| This oil rig operates in the channel off the coast of Goleta, Calif. Rigs such as these remove oil from the seafloor seeps
that otherwise would leak directly into ocean waters. Robert Harbison/CSM/File |
Ooey, gooey oil seeps on the seafloor
For kids: Off the coast of Santa Barbara, Calif., people aren't polluting the ocean with oil – nature is.
from the April 22, 2008 edition
Page 2 of 3
Asphaltum was used for face painting and as a base for jewelry inlaid with colorful stones. It was even used in games. In Huutch Uish, asphaltum-filled walnut shells were used as dice.
In the 1800s, pioneers used seep oil to grease their wagon wheels and farm equipment, and they burned it for light. By the 1860s, settlers were refining oil and using it as a crude pavement on roads. Miners dug pits and tunnels at seep sites, discovering oil, gas, and tar deposits.
By the 1900s, oil drilling was big business. Oil refined into gasoline and other fuels powered America's vehicles. And by the 1950s, offshore oil rigs were being built in the Santa Barbara Channel, removing millions of gallons of oil that would have naturally leaked from seeps.
Some animals adapt
While natural oil seeps have helped humans, they have not been as kind to animals. For thousands of years, animals became stuck and sank into ponds of liquid tar. The Rancho La Brea Tar Pits, a famous tar seep near Los Angeles, is a vast animal graveyard.
During the last Ice Age about 10,000 to 40,000 years ago, woolly mammoths, saber-toothed tigers, and even people became trapped in the tar. Thousands sank, and scientists called paleontologists now study their bones.
But other animals fared better. Generations of fish, dolphins, and whales that live in the Santa Barbara Channel have slowly adapted to the oil. Even though oil is poisonous, they tolerate it because seep oil is released in small amounts over time. Seawater mixes with the oil, diluting it and making it less harmful.
Seabirds living near the seeps have learned to swim or fly away from the slicks. That's good because birds and oil don't mix.
A bird's feathers insulate it against the cold, trapping its body heat and keeping it warm. Seabirds coated with oil try to clean their feathers by preening them with their bills. In doing so, they eat some of the oil, which is bad for them. But if they can't clean their feathers, the birds can't stay fluffy and warm in the cold water and could freeze.
Unfortunately, birds living in other parts of the channel don't seem to know about the dangers of the oil. When normal winds and currents change, the slicks spread elsewhere, and birds unfamiliar with oil get coated.
New discovery on the seafloor
Bottom-dwelling sea creatures have also adapted to the oil seeps. During a dive last year in a minisubmarine called Alvin, scientists saw a giant mound of tar near a seep. It was 262 feet across and 66 feet tall! It was overgrown with urchins and anemones and encircled by schools of fish.
Specialized bacteria that "eat" the oil lived nearby in slimy white mats. Clams, barnacles, and starfish that are specially adapted to survive near oil seeps thrived on the tar mountain. The scientists in Alvin had never seen anything like it. They said that the mound was a new kind of seafloor feature and that it probably started growing after an earthquake 23,000 years ago.
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