Subscribe to receive more articles like this: Print/digital

How careful control of gases gave MBARI the results they needed.

The Monterey Bay Research Institute (MBARI) sits on one of the most spectacular coastlines in California with Big Sur to the South and Santa Cruz to the North. But beneath this beauty the Monterey Bay and our oceans are changing rapidly due to the influx of CO₂ in our atmosphere. According to Dr. Jim Barry, a Benthic Biologist and Senior Scientist at MBARI, about one-third of human C0₂ gas emissions in our atmosphere are absorbed by the ocean, making the ocean 30% more acidic than just 100 years ago—now coined "Ocean Acidification."

Dr. Barry was concerned about how these rapidly increasing atmospheric C0₂ levels are affecting the myriad of marine animals in our seas, including possible differences in reaction to CO₂ between shallow and deep-sea water species.

Early in his experiments, however, Barry was frustrated with the quality of the mass flow controllers that controlled gas inputs to his aquarium tanks. Barry remembers that he would waste precious research time recalibrating the instruments almost every day and laboriously changing flow rates.

In 2005, this marine scientist was ready to make a change. He needed to find mass flow controllers that were accurate and stable. He drove to Sierra Instruments, also located in Monterey, California and met with Mark McMahon, Sierra's Scientific Product Manager. During this visit, Barry related his problem to McMahon who ended up demonstrating the capabilities of Sierra's digital MFC, "smart" Model 100.

The result of this discussion was that in 2005, Barry and his team installed nine Model 100s to control mixtures of O₂, N₂ and CO₂ to his aquarium tanks. He needed to vary the conditions to simulate past, present, and future ocean conditions. The O₂ levels vary from 1% to 20%, N₂ from 80% to 99% and C0₂ levels from 180 to 1500 ppm, depending on the desired atmosphere or ocean condition he was trying to simulate. With these parameters set, he could then measure development, growth, and the physiological responses to CO₂ or stress of the marine animals in the aquarium tanks.

Biologist Values the Ease-of-Use of the Pilot Module
With a push of a button on the Pilot Module, Dr. Barry can now change his CO₂ flow rates instantly and remotely, creating many varieties of oceanic atmospheres with the same set of conditions—same water, temperature, and animals. He simply plugs his Pilot Module into any one of his 9 Model 100s, makes a change in the gas flow rate, thus creating another atmosphere, and then unplugs it, and his gas flow will not deviate. If he wants to change his atmosphere again by entering different flow rates, it takes only seconds—a relief from his former days of manually changing flow rates.

Experiments Demand Accuracy
Dr. Barry states that "accuracy is essential" for these experiments. If his CO₂ readings are off by just 0.1%, the acidity of his simulated oceanic environment will change drastically, disrupting the experiment, requiring many hours of work to reset conditions and restart the experiment. This is no longer a problem with the Model 100's fast acting solenoid valve.

Results of Study
Dr. Barry discovered through his research that shallow-water animals acclimate better to CO₂ variations; they tolerate increased stress due to CO₂ better than similar deep-sea animals. He speculates that the continuing rise in atmospheric carbon dioxide will result in a faster rate of acidification, potentially affecting the productivity of our oceans, including marine fisheries that now provide a significant amount of consumable fish.

He is certain that this change is "the biggest environmental change in millions of years."

Paul Nesdore is Gases & Instrumentation Chief Editor. For more information on Sierra's Products call 831-373-0200. www.sierrainstruments.com

To read the entire article, sign up for a free subscription and then click on
Click here for the digital edition of the current issue