John Dabiri isn’t an oceanographer. And he’s not a biologist. But for more than a decade, he’s been studying tiny shrimp swimming through water. It hasn’t always been easy.
In 2014, he found his research on small crustaceans under the powerful microscope of Tom Coburn, then a Republican senator from Oklahoma who crusaded against government spending during his time in office. In his government “Wastebook” that year, the senator dismissed Dr. Dabiri’s work as the study of “synchronized swimming for sea monkeys.”
But Dr. Dabiri, an engineering professor at Stanford University, suspected there was more than could be seen by the naked eye in the movements of small marine creatures. And in a paper published Wednesday in Nature, he offered evidence that they are capable of playing a vital role in mixing up the many layers of the oceans and the minerals they contain. The findings may contribute to a better understanding of this process, which ensures that animals get proper nutrients and also plays an important role in regulating the planet’s climate.
Every night, trillions of sea creatures — whales, jellyfish, swarms of shrimp and plankton — take part in what some call the largest mass migration on the planet. From depths of at least 2,000 feet, they swim to the ocean’s surface, in a wave of animals that propagates as the sun sets around the planet. By daylight, they return below.
No one knows for certain how they know to do this — or why. But this vertical migration — especially the one completed every day by the some of the ocean’s smallest creatures — may be making big waves.
Half a century ago Walter Munk, a renowned oceanographer and geophysicist at Scripps Institution of Oceanography, described what we accept today about this mixing: that the wind and tide help. In one paper, he also briefly mentioned that vertical migrations could play a role.
Dr. Dabiri would later discover in an email exchange with Dr. Munk, that he had said this in jest: Animals can’t kick up much more water than the amount directly around their bodies.
Around the same time, it was deemed impossible that tiny animals, even collectively, could create enough power in their movements to stir up a layered ocean.
“These animals are individually small, and the ocean is enormous,” said Dr. Dabiri. “It sort of defies intuition that such small organisms could have a major impact in the oceans.”
Rather than going out on the ocean aboard a ship that cost $20,000 a day, Dr. Dabiri spent more like $100 a day in the lab using tall tanks filled with layers of salt water. He also used brine shrimp — Mr. Coburn’s “sea monkeys.” Although these shrimp do not live in the ocean, his team used them because they are a similar size to plankton or krill and their response to light allows the researchers to trigger vertical migrations on demand, which makes them easier to study.
They positioned lights at the top and bottom of the tanks, turning them on and off to attract the brine shrimp. They did this repeatedly — six times up and down for two hours — to replicate what you might actually see in the ocean if you dropped in to watch the marathon yourself. There, a mob of creatures can extend dozens of feet long and travel hundreds of feet. It would take you two hours to watch them pass by.
As expected, Dr. Dabiri’s team found that a single shrimp swimming upward doesn’t produce much flow, but combined with other shrimp, the mob created a downward jet that rapidly and irreversibly churned the different layers of seawater.
There’s a lot more to these results than just teaching sea monkeys to synchronize swim, Dr. Dabiri said. Showing that these physical dynamics are possible in the lab is a first step to better understanding the dynamic processes that drive ocean mixing and its role in the planet’s health. And some scientists are starting to accept that the daily commutes of animals may be more important than we thought.
In an interview on Thursday, Mr. Coburn stood by his dismissal of the research in 2014. He pointed out that Dr. Dabiri’s study used a different organism than the ones found in the ocean as its model, and called the work “junk science.”
“Basic research is fine. I’m for that. I want to expand the N.I.H., but I also want to get rid of the stupid stuff in there,” he said, referring to the budget of the National Institutes for Health. He added that scientists must stand up to scrutiny. “It’s a nice, little, cute story, but to me, it’s meaningless.”
Dr. Dabiri acknowledged that before making any permanent conclusions, it will be important to confirm that similar dynamics exist when tiny crustaceans make their nightly commutes in the real ocean. Understanding the ocean better will help scientists predict the climate on land — and essentially, our future.
“We didn’t know when we started that we would have discovered this,” Dr. Dabiri said. “But we won’t know those things if we’re not supporting basic research.”