美国国家公共电台 NPR Great White Sharks Have A Secret 'Cafe,' And They Led Scientists Right To It（在线收听）

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Next we have a discovery about the ocean, which scientists learned from great white sharks. NPR's Merrit Kennedy has a story that reveals how much we don't know about what's underwater.

MERRIT KENNEDY, BYLINE: Barbara Block has been studying the white sharks for decades. The Stanford marine biologist says scientists previously thought they stayed close to shore, snacking in waters with lots of food. But her view of the sharks started to change nearly 20 years ago when she began putting tags on them. The results were surprising.

BARBARA BLOCK: Through the years, we had gotten back enough tags to figure out that white sharks had sort of a hidden life.

KENNEDY: The tags showed that the sharks were moving up and down the coast of California and Mexico. But for part of the year, they appeared to be swimming far out to sea, more than a thousand miles away. Satellite images suggested it was an ocean desert, a place with very little life. The mystery of what was drawing the sharks to this strange place set new research in motion. What were the sharks doing out there?

BLOCK: We wanted to know if there was a hidden oasis that was formed by the currents that we couldn't see from space.

KENNEDY: So to find out, last fall, the scientists tagged more sharks than they'd ever done in a single season. Some of these animals they've known already from years of research. They've even given them names.

BLOCK: Eugene, Tilden, Leona.

KENNEDY: The sharks swam off. Then this spring, the research team set off on a ship called the Falkor towards the mysterious area, hoping to find the animals they tagged. Block says they all felt the pressure.

BLOCK: And so there's a lot of expectation when you put technology on an animal and then you take an expensive ship like the Falkor with 40 people to a box in the middle of the ocean and expect that these white sharks are going to be there.

KENNEDY: Sure enough, though, the animals did come to this remote place.

BLOCK: Just as we predicted, the sharks showed up right in the cruise box.

KENNEDY: Their tags were programmed to pop off and float to the surface. Each time one did, it would trigger an open-ocean treasure hunt as the team tried to find something the size of a microphone in an area about the size of Colorado. These sophisticated tags record things like temperature and pressure.

BLOCK: We doubled our current 20-year data set in three weeks.

KENNEDY: And after the tags popped up, the scientists would use a bunch of techniques to learn about the water below. For example, they lowered in a remotely operated underwater vehicle to take video of the deep. They also gathered DNA samples from the water and threw nets overboard to try to catch specimens.

BRUCE ROBISON: We expected it to be the desert that the textbooks sort of advertised that it would be.

KENNEDY: That's Bruce Robison, a senior scientist at the Monterey Bay Aquarium Research Institute. And he says this was no desert. A layer of nutrient-rich plant life was deeper under the ocean than satellites could detect. And tiny creatures feed on it. And larger creatures feed on them - and up and up.

ROBISON: That makes a complete food chain, a ladder of consumption that made us believe that there was an adequate food supply out here for big animals like tunas and the sharks.

KENNEDY: The scientists have nicknamed this remote stretch of the Pacific the White Shark Cafe. The sharks themselves led them to this place, and the scientists think there could be more hot spots out there. Merrit Kennedy, NPR News.

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