Lead researcher John Guinotte, a marine biogeographer at Marine Conservation Biology Institute (Bellevue, WA) and colleagues say that increasing amounts of atmospheric carbon dioxide (CO2), driven by the burning of fossil fuels, are dissolving into the oceans, causing them to become slightly more acidic. This change in seawater chemistry could harm deep-sea calcifying animals like corals.
Cold-water corals that make their skeletons from aragonite a form of calcium carbonate (the main component of limestone) are most vulnerable. Cold-water, reef-building corals are prevalent in the North Atlantic, where there is a deep layer of water supersaturated with aragonite. In pre-industrial times, more than 95 percent of cold water reefs around the world were found in waters supersaturated with aragonite. However, this layer of supersaturated water is shrinking as concentrations of CO2 increase.
"Scientists have known for years that shallow-water tropical coral reefs are threatened by both warming oceans and chemical changes in seawater caused by the build-up of CO2 in the atmosphere. Above-average seawater temperatures have caused coral bleaching events throughout the world, and the calcification rates of corals exposed to more acidic conditions in laboratory experiments have shown worrisome
Contact: Annie Drinkard
Ecological Society of America