NEWS AND NOTES ABOUT SCIENCE
SEEKING THE SOURCE OF THE VANISHING GREAT SALT LAKE
The Great Salt Lake in Utah is roughly the same area as 75 Manhattans. It feeds and houses millions of birds of hundreds of species and provides the namesake of Utah’s capital city, and some credit it for the state’s trademarked claim to “the greatest snow on earth.” And it is vanishing. Since 1847, the volume of water in the lake has dropped nearly 50 percent. More recently, the change has been so dramatic, you can see it from space. In 2016, the Great Salt Lake reached its lowest levels in recorded history.
“Do we want to in 50 years change the name of our city to Salt City because the lake has gone away?” asked Wayne A. Wurtsbaugh, a retired aquatic ecologist at Utah State University.
He and his colleagues reported in an analysis published in Nature Geoscience in October that human consumption — not seasonal fluctuations or climate change — is primarily to blame for the Great Salt Lake’s desiccation. They hope that creating a better understanding of water flowing into and out of the lake may serve as a model for managing salt lakes that face similar threats.
The near collapse of salt lakes in places like Central Asia’s Aral Sea, Iran’s Lake Urmia and California’s Salton Sea deprived local environments of natural filtration systems, wildlife habitats and opportunities for human use. Left behind were dust storms that threaten human health and agricultural fields.
In the case of the Great Salt Lake, the researchers warn that an additional 30 square miles of lake bed could be exposed in the next 30 to 50 years if planned development and overuse continue.
Development and water diversion since the mid-19th century have consistently reduced water entering the lake. Agriculture caused a significant loss.
To save bodies of water like Great Salt Lake, reducing consumption will be critical in arid basins, the authors argue. Joanna Klein
HOW A GIANT TORTOISE GETS OFF ITS BACK
The giant tortoises of the Galápagos Islands have no natural predators, but their shells represent a mortal danger of their own. When flipped over, the animals — who regularly weigh in at more than 90 pounds — often struggle to find their feet. If they fail, they eventually die.
And for a giant tortoise with one shell type, the saddleback, big spills are a regular part of life.
“The saddlebacks live in places where you have a lot of lava rocks, so they should fall more often,” said Ylenia Chiari, a biologist at the University of South Alabama, comparing them with domed tortoises, another type that lives on flatter terrain.
Domed tortoises have rounded shells, and saddleback tortoises have flatter shells with flared edges and a raised neck opening.
Chiari thought the shells on the saddlebacks, with their edges and corners, had evolved to make it easier for these tortoises to get back up, and set out to test her hypothesis in a study that was published Nov. 30 in Scientific Reports. She was wrong, but her research offered additional insights into the anatomies of these endangered creatures and how they might have evolved to get back on their feet.
The larger size of the saddleback’s neck opening allows the saddleback to extend its longer neck farther, which biologists long assumed was a trait that helped the tortoise reach food in a drier climate.
The shell’s larger front opening also allows the
saddleback tortoises to use their long necks to help pick themselves up (they wiggle their feet to shift their balance, too). That hole and the longer necks “could have evolved to overcome the fact that selfrighting would have been more difficult in saddlebacks,” Chiari said.
Douglas Quenqua
THINGS LOOKED BLEAK UNTIL THESE BIRDS RAPIDLY EVOLVED BIGGER BEAKS
Conservationists have been warning of the damage invasive species can cause to habitats and native animals for years. But in Florida, an invasive snail might be helping an endangered bird species come back from the brink, researchers say.
The population of North American snailkites — birds that use curved beaks and long claws to dine on small apple snails in the Florida Everglades — had been dwindling, from 3,500 in 2000 to just 700 in 2007. Things began to look particularly bleak in 2004, when a portion of the Everglades was invaded by a species of larger snail that the birds had historically struggled to eat.
But the number of snail kites in the Everglades grew during the decade after the in vasion of the larger snails. The reason, according to a study published Nov. 27 in Nature Ecology and Evolution, is that the snail kites have rapidly evolved larger beaks and bod ies to handle the bulkier snails.
“We were very surprised,” said Robert Fletcher, Jr., an ecologist at the University of Florida and an author of the study. “We often assume these large-bodied animals can’t keep up with changes to the system, like invasions or climate change, because their generation times are too long. And yet we are seeing this in credibly rapid change in beak size of this bird."
The researchers found that beak and body sizes had grown substantially (about 8 percent on average, and up to 12 percent) in the years since the invasion.
Natural selection appears to play a role. Young snail kites with larger bills were more likely to survive their first year than snail kites with smaller bills, presumably because the large-billed birds were better able to eat the invasive snails.
By tracking the birds’ pedigrees, researchers found that large-beaked parents gave birth to large-beaked offspring, setting the stage for large-scale evolutionary change. Douglas Quenqua
STORM WAVES WITH THE POWER TO HEAVE MASSIVE BOULDERS OVER CLIFFS
On a flat peninsula in western Ireland bordered by shallow cliffs that rise from the Atlantic Ocean sits a field of boulders. Some weigh nearly four times more than a school bus. Now scientists have figured out how these boulders reached their high perches.
A study published Nov. 27 in the Proceedings of the National Academy of Sciences suggests that powerful storm surges swept the boulders inward. The findings might help scientists better understand the dangers of coastal storms, which climate scientists predict are bound to increase in our warming world.
John Dewey, a retired professor of geology at Oxford University, and Paul Ryan, a retired geologist at the National University of Ireland, dug into historic records, oceanographic data and field measurements. Both lighthouse records and measurements from offshore buoys point toward a landscape that is commonly ravaged by large storm waves.
Take a storm in 1861, which sent waves crashing over an approximately 220-feet-tall lighthouse near the boulder site. The waves broke the glass and flooded the lighthouse.
“Think of the power of a wave crashing on the shore that high,” Dewey said. A single cubic meter of water weighs roughly a metric ton, or about 2,200 pounds, which is roughly the weight of a giraffe. “If you’re throwing a wall of water, say 30 or 40 meters high over a large area, the volume of water is enormous and the crushing force is tremendous,” Dewey said.
The researchers found that the waves are powerful enough to wash massive boulders that originate beneath the ocean’s surface hundreds of feet inland — exactly where they are found in western Ireland. Those waves can even rip the boulders from the faces of surrounding cliffs. Then with each successive storm, other waves can pick them up and wash them farther inland. Shannon Hall
WELCOME TO PTEROSAUR PARK.
Paleontologists have uncovered more than 200 fossilized eggs belonging to the flying reptiles that soared during the age of dinosaurs. The discovery, announced Nov. 30 in the journal Science, is the largest collection of pterosaur eggs found.
“I remember looking at the specimens and saying that’s not possible,” said Alexander W.A. Kellner, a paleontologist at the Federal University of Rio de Janeiro and an author on the paper. “We had less than 10 eggs before and now we have found hundreds in one spot.”
The find could help advance understanding about the early lives of the extinct winged creatures, including their relationships with their parents.
Pterosaurs terrorized the skies for more than 160 million years until they went extinct alongside the dinosaurs some 66 million years ago. They are the largest animals to have ever flown.
The species that laid the recently discovered eggs is known as Hamipterus tianshanensis. It lived during the early Cretaceous period and its wings stretched about 11 feet. It also sported a thick forehead crest and had a mouth full of pointy teeth for snatching fish.
Xiaolin Wang, a paleontologist at the University of Chinese Academy of Sciences, Beijing, and lead author of the study, discovered the eggs in a 120-million-year-old pterosaur boneyard in the arid Gobi Desert in northwestern China. When the pterosaurs thrived, the place was most likely a lush lakeshore. The team suggested that a strong storm most likely washed the eggs into the lake, where they were buried alongside pterosaur bones and preserved for millions of years. Nicholas St. Fleur