Photograph by Harry Harding
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A damaged coral reef can become “ghostly quiet” if inhabitants depart—but a research study has shown that playing the sounds of a healthy reef can lure some inhabitants back.
Photograph by Harry Harding

Sound to heal reefs, bites to spur blooms, and other wonders

Scientists looking for solutions to human and environmental ills are playing audio underwater, growing new heart tissue, and more.

This story appears in the October 2020 issue of National Geographic magazine.

 Sounds boost health of ailing coral reefs

Healthy coral reefs are pretty noisy places. “The crackle of snapping shrimp and the whoops and grunts of fish combine to form a dazzling biological soundscape” that draws juvenile fish looking for a place to settle, says marine biologist Steve Simpson. When a coral reef gets degraded, inhabitants disappear and the reef becomes “ghostly quiet,” he says. “But by using loudspeakers to restore this lost soundscape, we can attract young fish back again.” In 2017 Simpson and an international team of scientists placed loudspeakers along Australia’s Great Barrier Reef right after a mass bleaching event to see if playing the sounds of a healthy reef could entice fish to repopulate a damaged one. After six weeks, twice as many fish settled on bleached patches of reef where sound was played as on patches where no sound was played, according to the team’s study, reported in Nature Communications. “Fish are crucial for coral reefs to function as healthy ecosystems,” says marine biologist Tim Gordon, the study’s lead author. “Boosting fish populations in this way could help to kick-start natural recovery processes.” —Annie Roth

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If European bumblebees are hungry for pollen but plants aren’t flowering, the bees know how to speed up the blooming, scientists have found.

Bite makes plants flower

Bumblebees force plants to flower by biting their leaves—a discovery that may help improve agriculture. When common European bumblebees and their larvae emerge in spring, pollen is all they eat. Scientists recently found that if plants aren’t flowering, the bees bite them—and those incisions somehow speed the arrival of pollen-laden blooms. When scientists tried to mimic the marks, the plants bloomed earlier, but not as early as they did for bees. 
—Virginia Morell

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 A gift wrapped in tissue

With a heart’s blood and cells removed, a scaffold of connective matter remains. Texas Heart Institute scientist Doris Taylor supplies stem cells, oxygen, and blood to the “ghost heart”—and new heart tissue grows. Taylor’s team has grown more than a hundred test hearts and expects to create hearts suitable for transplant in the near future. —Patricia Edmonds