Taking the lab into the ocean: A fleet of robots tracks and monitors
microbial communities
Researchers enabled a trio of self-driving robots to locate, follow, and sample a layer of microbes as they drifted in an open-ocean eddy

Date:
January 13, 2021
Source:
Monterey Bay Aquarium Research Institute
Summary:
Researchers enabled a trio of self-driving robots to locate,
follow, and sample a layer of oceanic microbes as they drifted in
an open-ocean eddy north of the Hawaiian islands.



FULL STORY ========================================================================== Researchers from MBARI, the University of Hawai'i at M?noa (UH M?noa),
and Woods Hole Oceanographic Institution, after years of development
and testing, have successfully demonstrated that a fleet of autonomous
robots can track and study a moving microbial community in an open-ocean
eddy. The results of this research effort were recently published in
Science Robotics.


========================================================================== Autonomous robotic fleets enable researchers to observe complex systems
in ways that are otherwise impossible with purely ship-based or remote
sensing techniques. In a time when the COVID-19 pandemic is reducing opportunities for researchers to go to sea, autonomous fleets offer an effective way to maintain a persistent presence in features of interest.

Oceanic microbes are essential players in the global climate system,
producing roughly half of the world's oxygen, removing carbon dioxide,
and forming the base of the marine food web. Open-ocean eddies can be over
100 kilometers (62 miles) across and last for months. Phytoplankton (a
kind of microscopic algae) thrive when these eddies spin counterclockwise
in the Northern Hemisphere and bring nutrient-rich water from the depths
up toward the surface.

"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," said Brett Hobson, a senior mechanical engineer at MBARI and a coauthor of this study. Researchers have struggled to study the DCM because at depths of
more than 100 meters (328 feet), it can't be tracked with remote sensing
from satellites. Moreover, the position of the DCM can shift more than
30 meters (98 feet) vertically in just a few hours. This variability in
time and space requires technology that can embed itself in and around the
DCM and follow the microbial community as it drifts in the ocean currents.

Ed DeLong and David Karl, oceanography professors in the UH M?noa School
of Ocean and Earth Science and Technology (SOEST) and co-authors of the
study, have been researching these microbes for decades. DeLong noted that these teams of coordinated robotic vehicles offer a vital step toward autonomous and adaptive sampling of oceanographic features. "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," he explained.

During the Simons Collaboration on Ocean Processes and Ecology (SCOPE)
Eddy Experiment in March and April 2018, researchers used satellite
imaging to locate an eddy north of the Hawaiian Islands. They deployed
a hi-tech team of three robots -- two long-range autonomous underwater
vehicles (LRAUVs) and one Wave Glider surface vehicle -- from the Schmidt
Ocean Institute's (SOI) research vessel Falkor.



==========================================================================
The first LRAUV (named Aku) acted as the primary sampling robot. It was programmed to locate, track, and sample the DCM. Using an onboard 3rd- Generation Environmental Sample Processor (3G-ESP), Aku filtered and
preserved seawater samples, allowing researchers to capture a series of snapshots of the organisms' genetic material and proteins.

The second LRAUV (named Opah) acoustically tracked Aku and spiraled
vertically around it to collect crucial information about the environment surrounding the DCM. LRAUVs Aku and Opah carried a suite of sensors to
measure temperature, salinity, depth, dissolved oxygen, chlorophyll concentrations, optical backscatter, and photosynthetically active
radiation. Aku remained submerged for several days at a time sampling
the DCM, while Opah surfaced every few hours to relay information via
satellite back to scientists on the ship. A Wave Glider surface robot
(named Mola) also tracked Aku with sonar and communicated with the
science team aboard the Falkor.

"This work is really the fulfillment of a decades-long vision," said
MBARI President and CEO Chris Scholin. Scholin has been engaged in
this effort since he was an MBARI postdoctoral researcher seeking to
develop autonomous sampling technology for marine systems. "Coordinating
a robotic fleet to show how microbial communities react to changing
conditions is a game-changer when it comes to oceanographic research."
The researchers determined that Aku accurately and consistently tracked
the DCM over the course of its multi-day sampling missions. By tracking
the temperature corresponding to the peak of chlorophyll (an indicator of phytoplankton) in the DCM, the LRAUV maintained its position within the
DCM even as this biological feature moved as much as 36 meters (118 feet) vertically in four hours.

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

Beyond the extraordinary engineering feat of organizing this robot
ballet, the study also offers key takeaways related to how the biological community behaves inside a swirling eddy. RNA measurements reveal that as
the eddy weakened into the second leg of the experiment, the phytoplankton biomass in the DCM decreased. "Much like our own team of researchers,
each of the robots in the fleet is a specialist contributing to the experiment," said John Ryan, a senior research specialist at MBARI and a coauthor of the study. "This adaptive approach gives us a new perspective
on the environmental processes going on inside and around this plankton community." These robotic fleets are now also being used to monitor
other key disturbances to ocean health like 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.

This research is supported by the National Science Foundation, the
Simons Foundation, the Gordon and Betty Moore Foundation, the Schmidt
Ocean Institute, the David and Lucile Packard Foundation, and the State
of Hawai'i.


========================================================================== Story Source: Materials provided by
Monterey_Bay_Aquarium_Research_Institute. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Yanwu Zhang, John P. Ryan, Brett W. Hobson, Brian Kieft, Anna
Romano,
Benedetto Barone, Christina M. Preston, Brent Roman, Ben-Yair
Raanan, Douglas Pargett, Mathilde Dugenne, Angelicque E. White,
Fernanda Henderikx Freitas, Steve Poulos, Samuel T. Wilson, Edward
F. DeLong, David M. Karl, James M. Birch, James G. Bellingham,
Christopher A.

Scholin. A system of coordinated autonomous robots for Lagrangian
studies of microbes in the oceanic deep chlorophyll maximum. Science
Robotics, 2021; 6 (50): eabb9138 DOI: 10.1126/scirobotics.abb9138 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/01/210113144505.htm

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