What is ocean acidification?

The oceans absorb an estimated 22 million tons of carbon dioxide from the atmosphere every day. This shields the greenhouse effect by taking the planet-warming gas out of the atmosphere and storing it in the ocean. This causes huge problems for ocean life. This carbon mixes with the salt water to create carbonic acid, which immediately breaks down, forming bicarbonate and hydrogen and this excess hydrogen increases the water’s acidity.

Higher acidity, in turn, makes life difficult for marine animals by creating problems in their ability to form shells and skeletons. For plankton and many other species at the bottom of marine food chains, this means slower growth and population decline. These problems trickle up to affect the large fish that depend on smaller organisms for food.

Acidification also causes some coral species to grow more slowly or disappear. Since coral reefs support 25 percent of the ocean’s species of fish, this spells widespread trouble. Marine ecosystems are so interconnected, in fact, that scientists cannot predict the full effects of acidification. They only know that changes in the availability of food and in community structure can scale up quickly.

http://scienceprogress.org/2011/09/ocean-acidification-beyond-the-carbon-debate/