Ocean Acidification

Definition

Ocean acidification refers to the process by which the pH level of the Earth's oceans decreases due to the absorption of excess carbon dioxide (CO2) from the atmosphere. This change in acidity impacts marine life and ecosystems, particularly those that rely on calcium carbonate for their shells and skeletons, such as corals and some shellfish. The phenomenon is closely linked to changes in acid-base chemistry and has significant implications for the global carbon cycle and climate dynamics.

5 Must Know Facts For Your Next Test

1. Since the beginning of the Industrial Revolution, ocean surface waters have absorbed about 30% of the CO2 emitted by human activities, leading to a significant decrease in pH levels.
2. A decrease in ocean pH can impair the ability of calcifying organisms to produce their calcium carbonate structures, which affects their survival and growth.
3. Coral reefs are particularly threatened by ocean acidification, as lower pH levels hinder coral calcification, making them more susceptible to bleaching and other stressors.
4. Ocean acidification can disrupt marine food webs by affecting species at various trophic levels, potentially leading to reduced biodiversity and altered ecosystem dynamics.
5. The effects of ocean acidification are not uniform across all regions; areas such as upwelling zones experience more pronounced changes in acidity due to naturally occurring processes.

Review Questions

• How does ocean acidification impact calcifying organisms and what are the broader ecological consequences?
  • Ocean acidification negatively affects calcifying organisms like corals and shellfish by making it more difficult for them to produce their calcium carbonate structures. As these organisms struggle to grow and survive, it can lead to declines in their populations, which disrupts marine food webs. The loss of these key species can result in decreased biodiversity and a decline in ecosystem health, ultimately affecting fisheries and coastal communities that rely on these marine resources.
• Discuss the relationship between ocean acidification and the carbon cycle, highlighting how human activities contribute to this issue.
  • Ocean acidification is closely tied to the carbon cycle because increased levels of atmospheric CO2 from human activities, such as fossil fuel combustion and deforestation, lead to higher amounts of CO2 being absorbed by the oceans. This absorption lowers the pH of seawater, which directly impacts marine life. Understanding this relationship is crucial for developing strategies to mitigate CO2 emissions and address both climate change and its effects on ocean chemistry.
• Evaluate the long-term implications of ocean acidification on global marine ecosystems and potential socio-economic consequences for human communities.
  • The long-term implications of ocean acidification on global marine ecosystems could be profound, resulting in shifts in species composition and loss of biodiversity. Key ecosystems like coral reefs could collapse, leading to diminished fish populations and loss of habitat for countless marine species. Socio-economically, communities dependent on fisheries may face economic hardship as fish stocks decline and ecosystems become less resilient to other stressors like climate change. This complex interplay highlights the urgent need for comprehensive policies aimed at reducing CO2 emissions and protecting vulnerable marine environments.

Related terms

Carbon Cycle: The series of processes by which carbon compounds are interconverted in the environment, involving both natural sources and human activities that influence atmospheric CO2 levels.

pH Scale:

A scale used to specify the acidity or basicity of an aqueous solution, with lower values indicating higher acidity and higher values indicating higher alkalinity.

Calcifying Organisms: Marine organisms that produce calcium carbonate structures, such as shells or skeletons, which are vulnerable to changes in ocean acidity.