Robot Larvae Deployed off San Francisco
Scientists from the University of California, Davis, are deploying “robot larvae” into the ocean at Bodega Bay, just north of San Francisco.
The robots mimic clouds of microscopic marine larvae, such as baby crabs, mussels, clams and rockfish. The data the bots bring back provide some of the first direct confirmation of a decades-old and contentious scientific mystery: Where do marine larvae go?
Looking somewhat like Minions, the robots’ bodies are fire extinguisher cylinders painted bright yellow. Skirtlike white fan blades at their “waists” make them spin as they rise or sink, and a gyro inside estimates vertical speed. Sprouting from their black-capped tops are LEDs and a pinger for tracking, and antennas, GPS and satellite communications. Environmental sensors log salinity, temperature, light, depth and swimming speed.
The robots, officially called Autonomous Behaving Lagrangian Explorers, or ABLEs, are programmed to behave like a group of larvae throughout their development. Nine of them are currently being deployed by the research team.
The research carries implications for a range of issues, including managing marine protected areas, fisheries, invasive species and the impacts of climate change.
“How can you effectively manage something if you do not know where it goes, how it got there, and how it gets back?” said project lead scientist Steven Morgan, a professor of marine ecology with the University of California. “The fate of larvae has been a mystery since they were discovered.”
A single female marine organism can release hundreds or thousands of larvae at once. For a century, the prevailing thought was that after the larvae were born, they would drift out to sea much like the seeds from a dandelion flower, with little to no control of their movements. To survive was to win the lottery, only the lucky few could withstand the rough and tumble of the wild ocean and grow to make it back to their adult homes. The idea, though widespread, has gone untested because scientists cannot track microscopic larvae as they develop for weeks while being transported by currents.
The lottery idea never made sense to Morgan, however.
The robot larvae, which Morgan and his colleagues have been deploying for hours or days at a time, reveal that larvae control their movements by swimming vertically. They also stay much closer to the shoreline than expected.
Larvae of most species go only a mile from shore rather than far out to sea, as was once thought. They move up and down in the water column and return toward the shore using currents like a conveyor belt. Most stay below the strong surface currents to avoid getting carried out to sea.
“People have a hard time believing that microscopic larvae control their movements in strong currents because they’re so small,” said Morgan. “People can’t get over the fact that they are designed evolutionarily to do this.”