Ocean Acidification

Calcium Carbonate is very important in the formation of reef forming corals. It is the compound that makes up the skeleton of all hard corals and holds the structures together.Calcium carbonate (CaCO₃) allows corals to anchor themselves together and build reefs.

 The effects of ocean acidification contrast sharply with those of coral bleaching because you can’t see it. The results are not immediate and they lead to a decline in the already slow rate of growth.Without the help of the algae zooanthellea, corals have to shift energy from the growth process to obtaining more food. In addition, the growth that can occur is left brittle and weak. So the end product of both ocean acidification and bleaching is that hard coral species become slow growing, weak and vulnerable to physical impact.

Traditionally in Maldives, much of the corals around the islands buffer it from frequent tropical storms. Unfortunately, now with the increasing storm numbers due to climate change and with brittle coral protection, low lying islands are completely vulnerable and unprotected. This also causes the weak reefs to become broken or damaged, leaving them unable to recover and grow.

http://news.bbc.co.uk/2/hi/science/nature/7933589.stm

So what is causing the decrease in pH in the ocean? Ocean acidification unlike coral bleaching is not a direct affect of climate change because it relies solely on the increase of CO₂ in the atmosphere (OA_EPOCA). As the partial pressure of CO₂ increases in the atmosphere, the concentration of CO₂ will increase in the ocean in order to reach an equilibrium state. With an increased concentration of CO₂, the ocean’s chemistry becomes altered. This comes from a very important biological equation:

 [CaCO₃] <---> [Ca²⁺] + [CO₃^2-]

 ("The Key...", 2009). The increase of CO₂ decreases the number of free carbonate ions (CO₃^2-) which results in the reaction shifting to the right in order to establish equilibrium ("The Key...", 2009). This shift right will cause the break down of CaCO₃, therefore causing the reef to dissolve. Coral already stressed by the increased heat will now have to put more energy to prevent themselves from disintegrating (OA_EPOCA).