Floating robots track ocean plankton

Two floating robotic devices bobbing somewhere in the northern Pacific Ocean are collecting data about plankton and other organisms, beaming it to satellites and ultimately to researchers
who are teasing apart the mysteries of the ocean's carbon cycle.

The ocean absorbs, or sequesters, nearly a third of the roughly two
billion metric tons of manmade carbon that spews into the atmosphere
annually, likely contributing to global warming.

The ecologically crucial job of absorbing carbon -- called "fixing" -- in
oceans falls to single cell plant-like organisms known as phytoplankton,
which after performing their tasks get eaten by other animals or die
naturally in a day's time.

"Because the carbon-fixing animals which are so important only live a day,
it is crucial to learn as much about them as you can when the opportunity is
there," said Jim Bishop of the Lawrence Berkeley National Laboratory in
Berkeley, Calif. "In the past, you had to observe their cycle from a ship,
an expensive and dangerous task, especially during bad weather."

Instead, the researchers rely on the floats, known as Sounding
Oceanographic Lagrangian Observers or SOLOS, to live among and observe the
plankton's cycle without jeopardizing human life and budgets.

The metallic floats resemble a tank of gas like those found in a dentist's
office. They are equipped with carbon biomass sensors, an oil-filled bladder
that controls floatation by expanding and contracting and communications
equipment among other things.

Bishop said the devices make two dives a day, sometimes going as deep as
1,000 meters (1,100 yards) or a quarter of the way to the sea floor.

After each dive, they resurface and communicate their findings via a
two-way telemetry to ORBCOMM satellites.

"The great part about the satellite link is that it enables us to
communicate with the float rather than just receive its data," he said.

"This project seems designed to learn more about the plankton cycle, which
is critical," commented Terry Snell, a biologist at Georgia Institute of
Technology in Atlanta. "Plankton serve the function of trees on land so when
they don't work well, the ocean doesn't work well. This type of work then is
important."

LBNL's Bishop said the day the floats were deployed began tensely: the
company that controlled the satellite had run into financial problems,
casting doubts that it would remain in business.

"We had designed the floats to work only with those satellites so my
fingernails were non-existent that day," he said. "Fortunately, it worked
out."

The floats, standard oceanographic tools used to measure temperature,
salinity and currents, are built by Scripps Institution of Oceanography in
La Jolla, Calif. But Hughes and fellow researchers from LBNL affixed the
biomass sensor to them, essentially creating the first robotic carbon
observers, they said.

Some researchers believe the ocean, already an efficient storage tank for
carbon, could be made to absorb more without harming its ecosystem.

The Department of Energy's Center for Research on Ocean Carbon
Sequestration is studying two strategies. One idea is to pump liquefied
carbon dioxide a thousand meters deep or deeper into the water. Another
strategy, based on the knowledge that iron actually causes carbon-fixing
plankton to better use nutrients and blossom more fully, is to add iron
filling to some parts of the ocean.

The SOLOS were launched on April 10 from the Coast Guard icebreaker Polar
Star.

Tim Wood, also at LBNL, said the devices should continue working into the
fall but could make it until December if their workload is scaled back.

vny.com