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Robot fleet tracks, analyzes microbial community in the open ocean

In a proof-of-concept study, researchers demonstrated they could use a set of three robots to track microbes in the open ocean. Photo by Pexels/Pixabay
In a proof-of-concept study, researchers demonstrated they could use a set of three robots to track microbes in the open ocean. Photo by Pexels/Pixabay

Jan. 13 (UPI) -- In a first-of-its-kind proof-of-concept study, scientists have use an autonomous fleet of robots to track and analyze a community of microbes in the open ocean.

Marine microbes produce roughly half the planet's supply of oxygen and absorb the largest amounts of carbon dioxide. Ocean microbes also form the base of all marine food chains.

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In the open ocean, communities of microscopic algae, or phytoplankton, rely on currents to supply vital nutrients.

When open-ocean eddies -- twisting currents that can stretch for more than 60 miles -- spin counterclockwise in the oceans of the Northern Hemisphere, they bring especially rich concentrations of nutrients from the oceans' depths toward the surface.

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Most microbial communities in the open ocean thrive in a layer just below the surface called the deep chlorophyll maximum. In the DCM, microbes have access to sunlight from above and nutrients from below.

To better understand the relationship between microbes and eddies, researchers successfully programmed a trio of autonomous robots to conduct microbial analysis from within the DCM.

Scientists described their feat in a new paper, published Wednesday in the journal Science Robotics.

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"The research challenge facing our interdisciplinary team of scientists and engineers was to figure out a way to enable a team of robots -- communicating with us and each other -- to track and sample the DCM," study co-author Brett Hobson, a senior mechanical engineer at the Monterey Bay Aquarium Research Institute, said in a press release.

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Tracking microbes in the DCM with satellites and ship sensors is quite difficult, researchers said. Eddies and other types of currents are constantly contorting the subsurface layer and the DCM can shift vertically by several hundred feet in just a matter of hours.

"Open-ocean eddies can have a huge impact on microbes, but until now we haven't been able to observe them in this moving frame of reference," said co-author Ed DeLong, an oceanography professor at the University of Hawaii, Mānoa.

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After locating a powerful eddy north of the Hawaiian Islands, researchers released their trio of high-tech robots: two long-range autonomous underwater vehicles and a Wave Glider surface vehicle.

One of the two underwater robots, named Aku, was tasked with sampling and analyzing genetic material and proteins from the microbial communities found in the shifting, eddy-shaped DCM.

Meanwhile, the second underwater robot, named Opah, circled Aku collecting data about the environmental conditions within the DCM.

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The Wave Glider surface vehicle used sonar to keep taps on Aku, while Opah surfaced periodically to relay data to the Wave Glider, which relayed the observations to scientists on a nearby research vessel.

"This work is really the fulfillment of a decades-long vision," said Chris Scholin, the president and CEO of MBARI, who began developing autonomous sampling technologies while a postdoctoral researcher at the research institute.

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"Coordinating a robotic fleet to show how microbial communities react to changing conditions is a game-changer when it comes to oceanographic research," Scholin said.

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The data collected by the two underwater robots showed Aku successfully maintained its position within the DCM, even as the layer moved as much as 118 feet in less than four hours.

"Building an LRAUV with an integrated ESP that could track this feature was a milestone," said Yanwu Zhang, a senior research engineer at MBARI and the lead author of this study.

"Combining that sampling power with the agility of three different robots autonomously working together over the course of the experiment is a significant engineering and operations achievement," Zhang said.

Researchers hope to adapt the new marine microbe-tracking technology to analyze other ocean phenomena, including harmful algal blooms and oil spills.

"Given the rapid changes our ocean is undergoing as a result of human activities such as climate change, pollution and overfishing, this technology has the potential to transform our ability to understand and predict ocean health," said Scholin.

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