Coral bleaching is primarily caused by rising sea temperatures due to climate change, but there are several other factors that contribute to this phenomenon. One such cause is ocean acidification.
Ocean Acidification
Definition: Ocean acidification refers to the process by which the ocean becomes more acidic due to increased concentrations of carbon dioxide (CO2) in the atmosphere. When CO2 is absorbed by seawater, it reacts with water to form carbonic acid, which lowers the pH of the ocean.
Impact on Coral Reefs:
-
Calcium Carbonate Structures: Coral reefs are primarily composed of calcium carbonate (CaCO3), which is vital for the growth and structural integrity of corals. Ocean acidification reduces the availability of carbonate ions (CO3^2-), which are necessary for corals to build their calcium carbonate skeletons. This can hinder their growth and make them more vulnerable to erosion and damage.
-
Stress on Coral Symbiosis: Corals have a symbiotic relationship with zooxanthellae, photosynthetic algae that live within their tissues. Ocean acidification may disrupt this relationship, leading to increased stress on corals, which can contribute to bleaching events.
-
Reduced Resilience: Corals that are under stress from acidic conditions are less able to cope with other environmental stressors, such as elevated temperatures, pollution, and overfishing. This can increase the frequency and severity of bleaching events.
Overall, ocean acidification is a significant and often overlooked factor in coral bleaching, as it interacts with other stressors to compromise the health of coral reefs globally. Addressing CO2 emissions, therefore, is crucial not only for mitigating global warming but also for protecting coral ecosystems from the dual threats of rising temperatures and acidifying oceans.