November 20, 2012


By Rebecca Ruiz

For the past seven years, engineers and scientists at the Monterey Bay Aquarium Research Institute (MBARI) have been trying to solve a complicated chemistry problem.

The team had a vision: One day, they hoped to send an experimental chamber into the ocean that would measure the effect of falling pH levels on marine floor creatures in their native habitat. That acidification results from the ocean’s uptake of carbon dioxide, and some researchers have felt declining pH levels pose a major threat to underwater ecosystems.

For years, acidification experiments have been run in labs and aquariums, where animals like sea urchins received shock-level treatments of changing pH, though such dramatic fluctuations are actually rare.

An “in situ” experiment on the ocean’s floor to create and test the effects of acidification may not seem farfetched in the world of deep-sea exploration, but releasing carbon dioxide into the chamber to lower pH requires precisely timed, intricate chemical reactions. If that weren’t difficult enough, the team also wanted to create open-source technology that could be adapted to different ocean environments.

“The challenge for us is we want these experiments to stay as natural as possible,” William Kirkwood, MBARI’s senior R&D engineer, told Txchnologist. “It would be easy to make pH water, but we want natural detritus and food systems to all still play a part.”

Making the right calculations

The MBARI team solved both the technical and the chemistry problems and created the Free-Ocean Carbon-dioxide Enrichment (FOCE) experiment. The technology uses a semi-enclosed chamber to house sea animals that are exposed to controlled doses of carbon dioxide. MBARI’s latest FOCE was deployed from May 2011 until October 2012 and studied the behavior of sea urchins in a lower-pH environment.

(This diagram shows some of the main components of the deep-water FOCE system. The foam blocks are in different places on the later versions of this device. Courtesy MBARI.)

The trick, says MBARI senior research specialist Ed Peltzer, was accounting for how long it takes seawater to react with carbon dioxide, which varies depending on the depth and temperature of the water. In the deep Monterey Bay, for example, the carbon dioxide has to be released about 100 feet away from the chamber so the chemical reaction can occur before the current sweeps past the experiment. Otherwise, Peltzer says, the animal isn’t exposed to conditions as they might naturally occur.

Mastering this equation took work, and there were other technical problems. Analog sensors used to measure pH were too sensitive to stray electrical currents emitted by the chamber equipment. MBARI designed and built proto-types of new electronics and subsequently convinced electronics manufacturer Sea-Bird to make new sensors using its design.

But instead of hoarding these findings to create proprietary technology, the MBARI team developed xFOCE, an open-source platform and code that scientists around the world can use to conduct their own experiments. Kirkwood, the MBARI engineer, has since made several units built to local specifications.

Dr. David Kline, now at the Scripps Institution of Oceanography, was the first scientist to work with MBARI on an external experiment. But instead of a deep-sea FOCE, he needed one for the shallow reef off the coast of Australia. The pair came up with a system that could deal with high ultraviolet rays, higher seawater flow rates and an environment in which big storms and animals would likely disrupt the chamber. They also had to calculate the release of carbon dioxide for shallow, warm water.

“Because the technology and designs were open source, and [MBARI] were so willing to collaborate, it was really critical to our success,” Kline says.

The coral FOCE gave Kline the first-ever opportunity to conduct an acidification experiment in the reef’s natural environment, which included critical microbes and plankton. It deployed for eight months last year, and the results have been surprising: The reef eroded much faster than scientists had previously seen in lab settings. Kline believes that previous aquarium experiments were unable to capture the rapid erosion because they didn’t include naturally occurring food, predators and microbes.

Taking the lab to the ecosystem

Dr. Donna Roberts, ocean acidification project leader at the Antarctic Climate and Ecosystems Cooperative Research Center in Australia, has also worked with MBARI on creating a FOCE for another deployment. 

In summer 2014, her team will send four FOCE units to the Antarctic sea floor to monitor how polar ecosystems respond to higher carbon dioxide emissions. Such knowledge is particularly important, Roberts says, because cold waters absorb more carbon dioxide than warmer waters.

This will be the first FOCE unit deployed under ice, and will be at risk of being struck by the “bergy bits” of ice that break off over the summer. The chamber will have to be entrenched in the seafloor and built with materials that can withstand extreme cold.

The Antarctic FOCE will study seafloor communities that are often overlooked, but are essential to releasing vital nutrients back into the water to support the plankton that drive ocean productivity.

“While the research to date has been critically important in identifying mechanisms of change and species responses to ocean acidification, in order to predict real-world and community-wide responses we need to take the laboratory to the ecosystem, as we can’t take the ecosystem (especially in the Antarctic’s case) to the laboratory,” Roberts said in an email.

There is a FOCE experiment in the Mediterranean and discussion to start one in England; Kline plans to launch one for Scripps as well. Scientists will convene at a December meeting in France to learn more about FOCE and deploying their own experiments.

Peltzer sees the technology as the first step in decades of research on the effects of acidification, and he expects some surprises. In MBARI’s first study last year, for example, the sea urchins’ eating habits didn’t seem to be affected by the lowered pH. That’s a good sign, but MBARI biologists want to watch what happens over generations and to different outcomes like the reproductive cycle and growth.

“[FOCE] allows biologists to look at animals in the real world, not in the artificial world of an aquarium,” says Peltzer. “It’s a chance to see what happens when you’re not totally in control.”


Top Image: This photo shows one of the FOCE devices underwater at Heron Island, Australia, with the wind-power generator and floating computer control system in the background. Courtesy David Kline.

This post was originally published on the txchnologist.


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