Ocean acidification

Definition

Ocean acidification refers to the process by which the pH levels of the ocean decrease due to the absorption of excess atmospheric carbon dioxide (CO2), leading to a more acidic environment. This phenomenon significantly impacts marine ecosystems, particularly organisms that rely on calcium carbonate for their shells and skeletons, such as corals and shellfish, which are crucial components of marine biodiversity and food webs.

5 Must Know Facts For Your Next Test

1. Since the beginning of the Industrial Revolution, the ocean has absorbed about 30% of the CO2 released into the atmosphere, leading to a significant decrease in pH levels.
2. The current average pH of ocean surface waters has dropped from approximately 8.2 to 8.1, which represents a 30% increase in acidity since the late 18th century.
3. Ocean acidification can harm calcifying organisms by reducing their ability to form shells and skeletons, leading to declines in populations of species like corals and shellfish.
4. This process poses a serious threat to marine food webs, as many marine species rely on calcifying organisms for habitat and food.
5. The impacts of ocean acidification are not uniform; different regions may experience varying levels of acidification based on local factors such as upwelling and nutrient inputs.

Review Questions

• How does ocean acidification affect marine organisms that rely on calcium carbonate?
  • Ocean acidification decreases the availability of carbonate ions in seawater, which are essential for calcifying organisms to form their shells and skeletons. As pH levels drop, species like corals, mollusks, and some plankton struggle to maintain their structures, leading to potential population declines. This disruption not only threatens individual species but also impacts broader marine ecosystems reliant on these organisms for habitat and food.
• Discuss the relationship between increased atmospheric CO2 levels and the observed changes in ocean chemistry.
  • Increased atmospheric CO2 levels result from human activities such as burning fossil fuels and deforestation. When CO2 is absorbed by seawater, it undergoes chemical reactions that lead to the formation of carbonic acid, which lowers the pH of the ocean. This change in ocean chemistry can have far-reaching effects on marine life, particularly species that depend on stable pH levels for survival and growth.
• Evaluate the potential long-term ecological consequences of ocean acidification on marine ecosystems and human communities that depend on them.
  • Long-term ecological consequences of ocean acidification include diminished biodiversity as key species struggle to survive or adapt to changing conditions. The decline of coral reefs, which provide habitat for numerous marine species, could lead to reduced fish populations that many human communities rely on for food and income. Additionally, disruptions in marine ecosystems may affect tourism and coastal economies, highlighting the interconnectedness between healthy oceans and human well-being.

Related terms

carbon dioxide (CO2): A colorless, odorless gas that is a significant greenhouse gas and is absorbed by the oceans, contributing to ocean acidification.

calcification: The process by which marine organisms, such as corals and mollusks, produce calcium carbonate to form their shells and skeletons.

marine ecosystems: Complex communities of living organisms in ocean environments, including coral reefs, coastal areas, and deep-sea habitats, that can be heavily affected by changes in ocean chemistry.