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Oceanographers Develop New Robot to Image Zooplanktons as it Glides through Ocean

Oceanographers Develop New Robot to Image Zooplanktons as it Glides through Ocean

Engineers and oceanographers at Scripps Institution of Oceanography at the University of California San Diego joined hands to alter a common physical oceanography instrument for imaging zooplankton as it glides through the ocean.

Zooglider (top) with a selection of zooplankton imagery the robot has captured. (Image credit: Benjamin Whitmore)

The robot, named Zooglider by Mark Ohman, a Scripps biological oceanographer, uses a Scripps-developed glider called Spray as its platform. Ohman worked with Scripps instrument developers to equip the torpedo-shaped Spray gliders with a camera (called Zoocam) and a device which the researchers call as Zonar that collects acoustic data about zooplankton—free-drifting microscopic marine animals—similar to a sonar instrument.

Zooglider has the ability to obtain images of zooplankton every 5 cm (2 inches) to depths of 400 m (1300 feet) or more as it directs seawater into an onboard sampling tunnel. This is a revolutionary new instrument because it allows observations of microscopic life in its habitat and offers information related to that life in a spatial context. This improves the ability of scientists to obtain quantitative data about microscopic life within specified areas, a basic quest of biological oceanographers who investigate how marine organisms interact with their surroundings and how the physics and chemistry of their surroundings impact them.

Nearly all major processes in the ocean—carbon cycling, fisheries production, harmful algal blooms, ocean acidification, deoxygenation—are linked directly to the free-drifting animals of the open sea, the zooplankton. This is our first window on their world through a completely autonomous vehicle. We’re excited by the new opportunities Zooglider offers to visualize and understand these organisms, unperturbed in their natural environment.

Mark Ohman, Biological Oceanographer, Scripps Institution of Oceanography

The data gathered by Zooglider will offer insights about zooplankton dynamics that produces indirect information about the phytoplankton that is consumed by zooplankton and about the organisms that feed on zooplankton. Additionally, Zooglider offers an invaluable view of how marine life is reacting to climate change.

A description of the instrument has been reported in the January 2019 issue of the journal Limnology and Oceanography: Methods.

Engineers and physical oceanographers under the guidance of Russ Davis from Scripps developed the Spray glider beginning in the late 1990s. The 2-m (6.5-foot)-long robot can be programmed from a cell phone and has been used to detect and monitor currents in the Solomon Sea, El Niño conditions of California, and oil spills in the Gulf of Mexico. Spray gliders are programmed to operate along transects, diving and resurfacing in a seesaw manner because their buoyancy is controlled by internal bladders. At the surface, the data is transmitted back to researchers by the gliders.

Ohman, Davis, development engineer Jeff Sherman, and others incorporated a sonar system and an optical sensor package into the Zooglider. The authors stated that they selected Spray as a platform over other types of marine instruments due to its ability to reduce power consumption and stay in the ocean for periods of 50 days or more when more complex sensors are added. Furthermore, Zooglider’s design causes the least amount of disruption to the microscopic communities it studies.

Mark [Ohman] had a great idea to carry a highly magnified camera into the upper ocean on gliders to observe the zooplankton and Jeff [Sherman] and I had a great time designing the long focal length Zoocam and mounting it on a Spray glider to make Zooglider. Even more gratifying was to see how new facts of zooplankton behavior were deduced from its data.

Russ Davis, Scripps Institution of Oceanography

The device joins other instruments developed at Scripps to image marine life without taking organisms out of their habitat. In 2016, researchers at Scripps and UC San Diego’s Jacobs School of Engineering launched the benthic underwater microscope, or BUM, which allowed microscopic-scale views of marine life dynamics.

Co-author Jeffrey Ellen from UC San Diego’s Jacobs School of Engineering has been developing approaches through which Zooglider image data can be analyzed via machine learning. Other contributors include Kyle Grindley, Benjamin Whitmore, and Catherine Nickels of Scripps.

The Gordon and Betty Moore Foundation supported the development of Zooglider.

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