Ocean acidification

Educational value

• Ocean acidification is the lowering of ocean pH due to increased absorption of carbon dioxide. Over the last 200 years, the amount of carbon dioxide in the atmosphere has increased, mainly due to human activities such as deforestation and the burning of fossil fuels. Much of this increased carbon dioxide is being absorbed by the oceans, and it is changing the pH, which is a measure of acidity or alkalinity.
• As oceans become more acidic, there is less calcium carbonate available in the oceans. Calcium carbonate is required by many marine animals, including corals, crabs, oysters and bryozoans, to produce their shells and skeletons. Even small changes in ocean pH can have a large effect on these marine animals.
• Bryozoans play an important role in marine ecosystems, particularly in Australian and New Zealand waters where they are relatively large and numerous compared to those in the northen hemisphere. Bryozoans, sometimes known as moss animals, are a group of animals that live in colonies and form a structure known as a thicket. They are affected by changes to water pH and are useful for studying the effects of ocean acidity on marine ecosystems.
• Abby Smith is a lecturer and researcher at the University of Otago, New Zealand. She is a biogeochemist, which means she studies the interactions between chemical, geological and biological processes in the natural world. She is involved in bryozoan research, investigating the effects of ocean acidification.

Topics Acidification Scientists Human impact