Ocean acidification

Definition

Ocean acidification refers to the process by which the ocean becomes more acidic due to increased levels of carbon dioxide (CO2) in the atmosphere. As CO2 is absorbed by seawater, it reacts with water to form carbonic acid, which lowers the pH of the ocean. This change in acidity can have significant effects on marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons, impacting ecosystems and biogeochemical cycles.

5 Must Know Facts For Your Next Test

1. Since the beginning of the Industrial Revolution, ocean acidity has increased by approximately 30%, affecting marine ecosystems globally.
2. The increased acidity can hinder the ability of calcifying organisms to build and maintain their calcium carbonate structures, threatening coral reefs and shellfish populations.
3. Ocean acidification can also disrupt the food web by impacting phytoplankton, which are crucial for carbon cycling and as a food source for many marine species.
4. The process is expected to continue as CO2 emissions rise, with projections indicating further decreases in pH levels by the end of the century.
5. Monitoring programs and research initiatives are underway to better understand the long-term effects of ocean acidification on marine biodiversity and ecosystems.

Review Questions

• How does increased carbon dioxide in the atmosphere lead to ocean acidification, and what are the primary chemical reactions involved?
  • Increased carbon dioxide in the atmosphere leads to ocean acidification through its absorption by seawater. When CO2 dissolves in ocean water, it forms carbonic acid (H2CO3), which then dissociates into bicarbonate (HCO3-) and hydrogen ions (H+). The increase in hydrogen ions results in lower pH levels, indicating higher acidity. This process not only affects the chemistry of seawater but also has profound implications for marine life that depend on stable pH conditions.
• Discuss the implications of ocean acidification on marine ecosystems, particularly focusing on calcifying organisms.
  • Ocean acidification poses significant threats to marine ecosystems, especially to calcifying organisms like corals and shellfish. As acidity increases, these organisms struggle to absorb calcium carbonate needed to form their shells and skeletons. This can lead to weaker structures and decreased growth rates. As foundational species within marine food webs are affected, there may be cascading impacts on biodiversity, ecosystem services, and fisheries that rely on these organisms for survival.
• Evaluate potential strategies to mitigate the impacts of ocean acidification on marine environments and economies.
  • To mitigate the impacts of ocean acidification, several strategies can be considered. Reducing CO2 emissions is critical; transitioning to renewable energy sources and implementing carbon capture technologies could help decrease atmospheric CO2 levels. Additionally, protecting and restoring coastal ecosystems like mangroves and seagrasses can enhance their ability to sequester carbon. Finally, monitoring programs and research initiatives should be expanded to better understand local impacts and develop adaptive management strategies for vulnerable marine species and fisheries.

Related terms

pH: A measure of how acidic or basic a solution is, with lower values indicating higher acidity.

calcifying organisms: Marine species such as corals, mollusks, and some plankton that build shells or skeletons using calcium carbonate.

carbon cycle:

The series of processes by which carbon compounds are interconverted in the environment, including absorption by oceans and release through respiration.