Antarctic krill populations decreasing
Some fear havoc in food chain
July 6, 1997
Web posted at: 11:30 p.m. EDT (0330 GMT)
From Correspondent Rusty Dornin
SAN FRANCISCO (CNN) -- These are tough times at the bottom of the food chain.
Krill -- tiny shrimp-like creatures eaten by whales, seals, birds and fish -- are dwindling in number. Observers fear they may disappear altogether from the sea's menu.
"There has been almost a 90 percent decrease in krill abundance since 1980," said Valerie Loeb of the Moss Landing Marine Laboratory.
Krill is a main food source; its loss might cause a domino effect that could wreak havoc on the marine ecosystem. "Should this decline continue I would expect to see dramatic reductions in whale populations in that same area," said Kenneth Coale, also of Moss Landing.
Krill feed on algae beneath the ice. During the past 20 years the supply of sea ice has melted as temperatures have risen in Antarctica.
Many scientists blame global warming, which has been linked to fossil fuel emissions. "Some people view krill as the canary in the coal mine of global warming," Coale said. "It is certainly a wake-up call for scientists."
Already some penguin populations on Antarctic islands have been reduced by up to 50 percent.
Krill also is used as a supplement for chicken and cattle feed. Some 300,000 tons are harvested annually.
If the krill population is declining, researchers say harvesting could make the situation worse.
"The extent to which humans continue to harvest large amounts of krill will now, even more so, affect those natural populations of whales and penguins in the Antarctic," Coale said.
As the waters warm and the krill disappear, another creature, salp, replaces them. The problem is the salp has little appeal to hungry Antarctic creatures.
"Whales don't eat them. Penguins don't eat them. They're kind of a dead end for the food chain down there," Coale says.
If the warming is just a climatic fluctuation, krill population may return once temperatures cool. If not, Loeb says, "the Antarctic peninsula region in 20 years will be very different than it is today."
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