Ocean & Coastal Acidification

The burning of fossil fuels has resulted in an increase of carbon dioxide (CO2) in the atmosphere. The oceans absorb about one-third of this carbon dioxide, resulting in changes to ocean chemistry. Additionally, increases in freshwater and nutrient runoff can also cause changes in the carbonate chemistry of coastal waters. These local and regional processes play a particularly important role in acidification of the Southeast region. Explore the impacts to different organisms and ecosystem chemistry below.

The Chemistry

When there is too much CO2 in the water, it reacts with the carbonate ion that is essential for forming the mineral Calcium Carbonate, which is the mineral used by almost every species to form internal or external skeletons. This process is what we call acidification. Many different chemical contributions can contribute to decreasing the concentration of the carbonate ion (CO32-). Click here to learn more about the chemical processes that drive ocean and coastal acidification.

Impacts to Organisms

Plankton

Plankton, the base of the food web, that have calcium carbonate shells or exoskeletons, such as coccolithophores (phytoplankton) or krill (zooplankton) are most affected by acidified waters. Under acidic conditions, the calcium carbonate shells do not form "normally" and may appear to be transparent or have abnormal shapes. Since plankton are drifters, they have no defense against low pH waters. Click here for further references on our Resources Page.

Fish

Juvenile and larval forms of fish are particularly susceptible to acidification as they need calcium carbonate from the water to form parts of their bodies. Adult fish are also known to be affected by pH during sexual reproduction and mating. Since estuaries and coastal habitats are the primary nursery grounds for fish, coastal acidification hot-spots can impact economically important fisheries, even oceanic species. Click here for further references on our Resources Page.

Coral

Hard corals need calcium carbonate to form their hard skeletons. Acidified waters do not have enough calcium carbonate for corals and other animals to create their skeletons. Without calcium carbonate corals cannot survive. Without the biodiversity and habitat that coral reefs provide, not only would we loose important marine habitats and species, but also important economic and social resources. Click here for further references on our Resources Page.

Shellfish

Shellfish need the calcium carbonate from the water to make their shells. Acidified waters do not have enough calcium carbonate for shellfish to thrive. Various species of shellfish make up important economic industries . Shellfish also perform one of the most important ecosystem services in estuaries and coastal waters. They are filter feeders that essentially "clean" the water. Not only do they feed on plankton, but they remove particulate matter from the water and excrete it as sediment. Click here for further references on our Resources Page.