For years, shrimp and their other tiny, uncharismatic brethren collectively known as zooplankton were deemed too inconsequential to alter the oceans. Sure, they’re important food sources but it’s not like they could actually churn the high seas, right? Wrong, according to the new research published in Nature on Wednesday.
To see if tiny creatures—which the study adorably dubs “centimeter-scale swimmers”—have the ability to churn the ocean, researchers retreated to a dark lab on Stanford’s campus. There, they performed experiments using tanks, brine shrimp, and lasers that simulate night and day. The results show that the collective motion of brine shrimp up and down the water column can actually mix the water up. If the findings hold true in the open ocean, they could provide a whole new understanding of how our oceans get mixed.
“The widespread effects could include vertical transport of carbon, nitrogen, [and] oxygen by the organisms,” John Dabiri, one of the researchers behind the new study, told Earther in an email. “This could be positive, e.g. in the case of sequestration of our carbon emissions in the ocean. But it could be negative, e.g. if the nutrients lead to harmful algal blooms.”
The experiment that Dabiri—who has pioneered studying tiny swimmers’ movements with lasers, making him some kind of futuristic marine pied piper—and his colleagues undertook mimics what happens in the ocean on a regular basis. Shrimp, zooplankton, and other centimeter-scale swimmers migrate through the water column based on when the sun rises and sets everyday.
To see if that could be perturbing the ocean, Dabiri’s group set up two tanks filled with brine shrimp. The shrimp naturally sink because in sciencespeak, they have “negative buoyancy.” But when the researchers shined blue lights at the top of the tanks to simulate the sun, they migrated toward it, propelling water behind them like tiny, aquatic rockets (eat your heart out, Elon).
Using dye in the tanks, they were able to track the eddies left behind by the brine shrimp. Each individual shrimp produced eddies as it propelled itself upward, creating psychedelic images and movements that look like something out of a Pink Floyd video.
But it’s the combination of all these eddies that’s what matters. After a few repeated migrations meant to simulate how long it would take to move up the entire water column in the open ocean, the results showed that “irreversible mixing” occurred.
The lab experiments took place in tanks that were four and six feet tall. In the open ocean, plankton can move up to 1970 feet in a day, which means what Dabiri and his colleague saw in the lab could in theory take place across much bigger scales in the ocean. The next step will be doing more lab experiments to determine what the critical mass for mixing is, as well as to actually head to sea and find out what happens in the open ocean.
“I think that shipboard measurements are now feasible, since the lab experiments have given us clues as to what to search for as far as a signal of the animal mixing,” he said.
While I’m sure those types of experiments will be very insightful, they won’t be nearly as colorful.