Foraminifera, single-celled eukaryotes that construct shells (i.e. tests) of calcium carbonate, have played a vital role in the marine ecosystem’s lower trophic levels for hundreds of millions of years, incorporating CO2 in sea waters. In modern oceans, for example, in coral reef areas, they can produce between 10 to 1000 grams of calcium carbonate per square meter annually. Fossil records reveal that during geological periods such as the Jurassic and Cretaceous, which had significantly higher temperatures and carbon dioxide levels, foraminifera proliferated explosively. This suggests that foraminifera have the resilience to survive in extreme environments and are key agents in converting CO2 into a mineral substance. We promote research on the dynamics of CO2 through research on the calcification of foraminiferal tests.
Test formation by the benthic foraminifera Ammonia confertitesta. When forming their calcium carbonate tests, they uptake CO2 and Ca ions from seawater and regulate intracellular pH at the calcification site to crystallize calcium carbonate. The initial stage of calcification (top left) and the stage where the template of calcareous tests is formed (bottom left). They add small chambers made of calcium carbonate to create a relatively large tests for a protist (top right). Scale bars are 20 µm (top and bottom left images), and 100 µm (top right image).
