How does ocean acidification threaten corals and shell-forming mollusks?

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Ocean acidification, driven by the ocean's absorption of atmospheric carbon dioxide, poses a severe threat to coral and shell-forming mollusks by altering seawater chemistry. As acidity increases, the concentration of carbonate ions—essential building blocks for these organisms—declines.1

This process impacts marine calcifiers in several critical ways:

Reduced Structural Integrity: Corals and shellfish struggle to obtain the raw materials necessary to build and maintain their skeletons and shells. Under projected future acidity levels, these organisms may grow smaller or experience shell dissolution, leaving them more vulnerable to predators.1
Habitat Loss: Coral reefs, which serve as vital centers of biodiversity, face potential decline or disappearance as carbonate availability drops. This threatens the many species that rely on these reefs for habitat and food.1
Physiological Stress: Increased acidity can lead to acidosis in marine life, negatively affecting growth, reproduction, and overall health. For example, increased stress is linked to higher vulnerability to disease in oyster larvae.1

The rapid pace of these chemical changes may outstrip the ability of many species to adapt, potentially destabilizing entire marine food chains.1