Ocean acidification primarily impacts corals by making it harder for them to build and maintain their essential skeletons.
The Core Impact: Reduced Building Blocks
Corals construct their hard, protective skeletons using a mineral called calcium carbonate. This process, known as calcification, relies heavily on the availability of key chemical components dissolved in seawater.
A critical finding highlights this vulnerability: ocean acidification reduces the concentration of carbonate ions ([CO32−]) that corals need to build their skeletons. These carbonate ions are the fundamental building blocks that corals extract from the water and combine with calcium to form calcium carbonate.
Why Carbonate Ions Are Crucial
Think of carbonate ions as the "cement" corals use to build their homes. As the ocean absorbs excess carbon dioxide from the atmosphere, its chemistry changes, leading to a decrease in the concentration of these vital carbonate ions.
Consequences for Coral Health and Reefs
With fewer carbonate ions available, corals face significant challenges:
- Difficulty in Building Skeletons: It requires more energy for corals to collect the necessary ions from the surrounding water.
- Slower Growth Rates: Calcification slows down, meaning corals grow more slowly and are less able to repair damage.
- Weaker Structures: The skeletons they do build may be less dense or weaker, making them more susceptible to breaking from storms or physical impact.
- Increased Vulnerability: Overall, the reduced ability to build and maintain strong skeletons leaves corals more vulnerable to other stressors, such as rising ocean temperatures and pollution.
In essence, ocean acidification undermines the very foundation upon which coral reefs are built, threatening the entire ecosystem they support.
