Researchers hope the information the robots collect on where larvae move will improve monitoring of ocean health and better inform the design of future Marine Protected Areas.
On a blustery day at the head of north-central California's Bodega Bay, a team of researchers carefully lower a small school of repurposed, yellow fire extinguishers equipped with satellite transmitters into the choppy waves splashing against their vessel. One, two, three, four, the Minion-esque robots, fitted with a skirt of fan blades, bob in the water for no more than two minutes before their downward pumps turn on and they silently slip below the surface.
"For as long as we've known that marine larvae exist, we haven't known where they go," shouts Steven Morgan, a UC Davis marine ecologist, fighting to gain audible dominance over the fierce wind. Until now, that is.
In his hands, Morgan clutches another $1,200 larval robot, this one playfully dubbed ZOEA. He explains the hefty robots are designed to mimic the movements of near-weightless, microscopic larvae along the California coast. He hopes the information they collect on where larvae move will improve monitoring of ocean health and better inform the design of future Marine Protected Areas to ensure they account for needs of their tiniest creatures. More importantly, it will help to fill in a millennia-old knowledge gap about infant aquatic life.
Since the discovery of marine larvae, ecologists have believed all the different species—from baby shrimp to crabs to lobster—were at the mercy of strong currents, with little to no control over their own dispersal destinies. But scientists had no clue how they were moved throughout the water column. "It's been a huge mystery," said Morgan.
When scientists dug deeper in the decades that followed, they realized larvae actually exhibit unique movements and behaviors, exploiting bottom and surface currents to get where they want to go. Because these patterns govern the dispersal of some of the region's key marine species, understanding them is crucial for conservation.
It's been a long road for researchers to get to this point. Larvae transport isn't exactly a sexy issue after all, and when oceanographers first set out in the 1800s, they actually believed larvae were a separate species—not just infants. Yet larvae have long captured Morgan's imagination, ever since seeing the strange creatures for the first time as a young graduate student.
"They're microscopic. They're mysterious. Nobody knows anything about them and it's not like you see them on the nature channel," Morgan told me, as the R/V Mussel Point looped around the bay. The marine ecologist first saw a rough prototype of one of the Minion bots—technically known as Autonomous Behaving Lagrangian Explorers—created by North Carolina State University researchers Tom and Donna Wolcott about 25 years ago, when the duo was hoping to track the lives of Bermuda land crabs. The idea of mimicking larvae intrigued him.
After accruing enough financial support, the UC Davis team began construction in earnest in 2014, upgrading and modernizing the bots, working out the kinks, and testing them in swimming pools around campus and out in the field during the summer of 2015. At long last, Morgan began deploying the bots in groups of nine to 12 this past summer.
Each 10-pound bot is programmed to mimic one of the seven ways marine larvae move up and down in the water column. According to Morgan, some species have been found to prefer to stay low in bottom currents, while others prefer to frequently travel up and down during the day or night.
To do the same, the bots need to be able to sense exactly where they are in the water. This is accomplished via a temperature probe, pressure sensor, salinity gauge, and light measure. Then, over a two-week period (that's how long the battery lasts), Morgan and his team communicate with the bot, telling it to surface every four hours or so as to ping satellites that will chart its course and allow scientists to map their movements in real time.
"It's kind of like how you might track a lion with a collar across the Serengeti," he said, rotating the bot in his hands to show off all its different features, pausing on an LED (in case the team needed to find the bots at night). Behind him, brown pelicans struggled against strong updrafts to come to rest on rocky outcrops.
When the robots' deployment is over, John Largier, an oceanographer at UC Davis who focuses on marine transport, hopes the team will be able to glean new information on how to improve the network between protected ecosystems. "Marine larvae connect things in the ocean and [understanding how they move is] important for things like Marine Protected Areas, conservation plans, fisheries management, and climate change," Largier says.
Largier, who also serves on California's state task force to help to design Marine Protected Areas, said that in a few years, the data can be used to inform the designation of future MPAs in California. "If you had an MPA in Bodega Bay, and the next closest one is 200 kilometers away, you want to know whether larvae are moving between adjacent MPA sites to determine how [close] you put them," he explained from the stern. Moreover, determining whether or not marine larvae are returning to where they were born can help the task force delineate which areas to protect.
"It's just like terrestrial parks, and now we're putting them at sea," Morgan added.
Ultimately, the issue has long been that ocean science has lagged behind terrestrial science. "We're all ecologists at birth and we start understanding the world around us. This is alien," said Morgan, looking out over the water where a group of harbor seals had come to sun themselves on a sand bar. "We had no idea what was going on until scuba diving opened it up in the 1960s. There's so much unknown in the sea, including basic information like what a species' larvae looks like. This is the first chance to make larvae interesting to most people. It's got robots. It's got minions. And it's got alien-looking larvae."