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| A sunflower starfish found in a kelp forest in waters off the coast of Oregon before the sea urchin invasion. Scott Gross/Scott Gross via The Associated Press |
WITHINBUCKS - Kelp forests off the west coast are dying, and their decline threatens entire ecosystems of marine flora and fauna. Sea urchins may help the giant starfish that feed on them.
One of the reasons for the disappearance of kelp is the rapid increase in sea urchins that feed on it. This includes an estimated 10,000% increase in their numbers over the last few years in coral reefs surveyed off the coast of Oregon. Also, the rise in sea urchins may be due to a disease that nearly wiped out one of his main predators, his starfish, the sunflower. (Animals are not fish, so scientists prefer "sea stars" to "starfish.")
The team of scientists believes that had the sunflower starfish been there to prey on the sea urchins, the sea urchin population explosion might not have occurred, and restoring populations of the colorful creatures would have been beneficial to kelp forests and I believe that this was a significant undertaking for my research. It was published in Proceedings B of the Royal Society last month.
Scientists estimate there were once 5 billion sunflower sea stars along the coast from Alaska to Baja California. They have up to 20 arms and can grow up to 3 feet in diameter. Sea stars, at least, move at speeds up to 200 feet per hour. But most died from starfish wasting disease, believed to be caused by a virus.
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| Purple sea urchins are the main cause of the decline of kelp forests, and red sea urchins are also in danger of extinction, right? Gabriella Angotti Jones |
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| Sunflower starfish in an enclosure at the University of Washington. Matt Mills McKnight |
To test whether introducing artificially grown sunflower starfish would help, researchers near Washington's San Juan Islands planted 24 sunflower starfish and 300 purple sea urchins. field. They observed them under experimental conditions and recorded their hunting activity and food preferences. These were healthy sea stars, survivors who were not affected by wasting disease, presumably because they were resistant to the disease.
Scientists have found that starfish eagerly feed on both young and large adult sea urchins. When attacked by a starfish, sea urchins fight back, pinching part of the starfish's arm to push the attacker back. This is a delicacy for sea otters and human sushi lovers alike.
Is it realistic to re-establish sunflower starfish populations in captive breeders? Aaron W.E.
The Lost 24-Limbed Creatures That May Be Able to Save the Ocean's Forest
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