At least half of the oxygen in our atmosphere is created by ocean microbes, which also remove carbon dioxide and form the basis of marine food webs that support global fisheries. Scientists are now attempting to better understand the microorganisms, utilizing a new type of autonomous underwater vehicle.

The study is being led by Edward DeLong and David Karl, who are oceanography professors at the University of Hawai'i at Mānoa. To gather their data, they're using a fleet of three long-range autonomous underwater vehicles (LRAUVs), designed and built by colleagues at the Monterey Bay Aquarium Research Institute.

Each vehicle has a range of over 600 miles (966 km) and can use its integrated sensors to independently navigate the seas, locating and tracking phenomenon such as open-ocean eddies – these are masses of swirling water that can be over 100 km (62 miles) across, lasting for months at a time. When spinning counterclockwise, such eddies bring water from the depths up to the surface, where phytoplankton (microscopic algae) are able to access the life-sustaining nutrients that are brought with it.

As the LRAUVs travel, they use an onboard miniature robotic laboratory known as an integrated Environmental Sample Processor (ESP) to draw and process water samples from the surrounding ocean. These samples are checked for factors such as temperature, chemistry, and chlorophyll content – the latter of which is an indicator of phytoplankton – with the results being wirelessly transmitted to the shore or a nearby ship.

The three submersibles will begin open-ocean trials on Mar. 10 when they're deployed from a ship into an eddy near Hawaii, where they will gather data on its duration, stability, and influence on ocean systems.

"These new underwater drones will greatly extend our reach to study remote areas, and also will allow us to sample and study oceanographic events and features we can see by remote satellite imaging, even when ships are not available," says DeLong.

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