VOA慢速英語：科學(xué)家發(fā)現(xiàn)新方法抵制“赤潮”

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A leading scientist says researchers in Florida are close to developing a way to control the algae known to cause deadly “red tide.” Michael Crosby heads the Mote Marine Laboratory in Sarasota, Florida, a leading research organization.

A 10-month-old red tide has been killing ocean life along Florida’s southwestern coast. Huge numbers of dead fish have washed up on beaches from the city of Naples up to Tampa. Red tide can cause problems for humans too. Contact with the algae can cause breathing difficulties, burning eyes and skin pain.

On Monday, Governor Rick Scott ordered emergency measures to deal with the crisis. Crosby said he welcomed the move, which releases more money and resources to solve the problem.

Scientists field-testing solutions

The Florida Fish and Wildlife Conservation Commission suspects the red tide caused the deaths and strandings of hundreds of sea turtles this year. The agency also blames it for at least some of the 68 deaths of manatees. Other sea mammals killed include porpoises.

The body of an almost eight-meter-long whale shark also washed up on Sanibel Island, Florida, late last month.

Crosby said, scientists are currently testing a process that would pump red-algae-filled seawater through an ozone-treatment system. Then the purified water would be pumped back into the ocean or waterway.

Crosby said the experiments were carried out in huge 25,000-gallon tanks. He said all succeeded in removing the poisonous algae. Crosby said the water chemistry returned to normal within 24 hours.

Scientists also are studying the use of seaweed, parasitic algae and other organisms to fight the red tide.

A ‘bad bloom’

Red tides happen almost yearly in Florida. They start in the Gulf of Mexico, where microscopic algae cells called Karenia brevis feed on deep-sea nutrients. Ocean currents carry the algae close to the coast, usually in autumn.

The current Gulf Coast Florida bloom is the worst in more than ten years. It began last October and has spread across more than 80 kilometers of coastline.

“It’s a bad bloom,” said Richard Stumpf, a scientist who studies red tides for the National Oceanic and Atmospheric Administration (NOAA).

Stumpf said strong northerly winds that normally end red tides failed to form last winter. He said it is not clear why. And he said scientists are not sure if the winds will fail to form again.

Natural phenomenon

Scientist Michael Crosby said the red tide happened during the reproductive season for snook. The fish are important for both the environment and economy in Florida. Part of the emergency money ordered by the governor will be used to examine the red tide’s effects on that fish.

I’m Phil Dierking.

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Words in This Story

algae - n. simple plants that have no leaves or stems and that grow in or near water?

ozone - n. a form of oxygen that is found in a layer high in the earth's atmosphere?

parasite - n. an animal or plant that lives in or on another animal or plant and gets food or protection from it?

seaweed - n. a type of plant that grows in the sea?

strand - v. to cause (something, such as a boat or a sea animal) to become stuck on land