These large tubes are part of the antFOCE system. Chemical reactions occur more slowly in the frigid waters of the Antarctic, so these 30-meter-long tubes allow time for CO2-saturated seawater to become more acidified before it flows into the antFOCE experimental chamber. Image by Glenn Johnstone

Monterey Bay Aquarium Research Institute leads acidification experiments around the world

MBARI scientists and engineers have been developing new methods to study ocean acidification and its effects on marine organisms in their natural habitats for 15 years. Researchers around the world have been adapting MBARI instruments to perform their own experiments in habitats ranging from coral reefs to the Antarctic seafloor. These diverse projects have recently been highlighted in an article in the journal Progress in Oceanography.

Ocean acidification describes the chemical changes that occur as seawater reacts with excess carbon dioxide absorbed from the atmosphere. Key changes in the carbonate chemistry of seawater during acidification include an increase in the partial pressure of CO2, increased acidity (reduced ocean pH), and reduced levels of carbonate ions (CO32-). These chemical changes can be physiologically challenging for organisms, disrupting their internal acid-base balance and impairing calcification of shells or skeletons, ultimately increasing the “cost of living” to cope with higher ocean carbon levels. For some organisms, particularly some marine plants, increased CO2 levels can actually enhance growth, but for many organisms, the increased CO2 can impair behavior, growth, reproduction, survival, and other life processes.

Floating in the clear blue waters of an indoor test tank, MBARI’s first Free Ocean CO2Enrichment (FOCE) system was a circular cage of pipes intended to drench the area inside with water rich in carbon dioxide (CO2). Inspired by an approach to study the effects of rising CO2 levels on land called Free-Air CO2 Enrichment (FACE) experiments, FOCE was designed to answer a critical question—how do increasing levels of carbon dioxide in the ocean affect marine plants and animals?

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