Ocean acidification

Definition

Ocean acidification refers to the process by which the ocean becomes more acidic due to the increased absorption of carbon dioxide (CO2) from the atmosphere. As CO2 levels rise, they react with seawater to form carbonic acid, which lowers the pH of the ocean. This phenomenon can significantly impact marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons, such as corals and some shellfish, thereby affecting coastal and marine ecosystems.

5 Must Know Facts For Your Next Test

1. Since the Industrial Revolution, ocean surface pH has decreased by about 0.1 units, corresponding to a roughly 30% increase in acidity.
2. Ocean acidification poses a significant threat to coral reefs, as lower pH levels can hinder coral growth and lead to bleaching events.
3. Shellfish such as oysters and clams are particularly vulnerable to ocean acidification, which affects their ability to build shells and survive.
4. Changes in ocean chemistry due to acidification can disrupt marine food webs, potentially leading to declines in fish populations that rely on shellfish for food.
5. Coastal ecosystems, including mangroves and seagrasses, may also be affected by ocean acidification, impacting their ability to support diverse marine life.

Review Questions

• How does ocean acidification affect marine organisms that rely on calcium carbonate for their survival?
  • Ocean acidification reduces the availability of carbonate ions in seawater, which are essential for marine organisms like corals and shellfish to create their shells and skeletons. As the pH of the ocean decreases, these organisms may struggle to maintain their calcium carbonate structures, leading to weaker shells and increased vulnerability to predation and environmental stressors. This disruption not only threatens individual species but can also destabilize entire marine ecosystems reliant on these organisms.
• Discuss the broader ecological implications of ocean acidification on coastal ecosystems.
  • Ocean acidification has significant ecological implications for coastal ecosystems such as coral reefs, mangroves, and seagrasses. The decrease in pH can negatively impact coral growth and resilience, leading to less complex reef structures that support diverse marine life. Additionally, shellfish populations decline due to difficulties in shell formation, affecting species that rely on them for food. The resulting changes can lead to altered species interactions, shifts in community composition, and a loss of biodiversity in these crucial habitats.
• Evaluate the potential long-term effects of ocean acidification on human communities that depend on marine resources.
  • The long-term effects of ocean acidification on human communities could be profound, particularly for those whose livelihoods depend on fishing and aquaculture. As shellfish populations decline due to difficulty in shell formation and coral reefs weaken from acidification, local economies may suffer significant losses. Additionally, reduced biodiversity could affect ecosystem services such as coastal protection and tourism. Communities may need to adapt through sustainable practices or alternative livelihoods as the impacts of ocean acidification reshape marine resource availability.

Related terms

carbon dioxide: A colorless, odorless gas produced by burning fossil fuels, and a key contributor to global warming and ocean acidification.

calcium carbonate: A chemical compound that is essential for the formation of shells and skeletons in many marine organisms, which can be negatively impacted by decreasing pH levels.

marine biodiversity: The variety of life found in ocean ecosystems, which can be threatened by ocean acidification due to changes in habitat and food sources.