Although seawater is alkaline, this process causes the pH of seawater to lower and the acidity of seawater
to INCREASE, hence the term Ocean Acidification.
In the last 250 years the average pH of the surface ocean has fallen from 8.2 to 8.1
– a change of 0.1 units.
A change of 0.1 doesn’t seem like a lot, but since the pH scale is logarithmic, this means that the ocean has become 30% more acidic.
It is predicted that if nothing is done to significantly reduce our CO2 emissions, by the end of this century the pH level of the ocean could drop another .45 units – reflecting a 75% increase in acidity.
Although fish and squid do not have shells, they still require calcium carbonate to build tiny organs in their bodies that allow them to balance themselves in water and detect/avoid predators.
Those Hydrogen ions don’t just increase seawaters' acidity, they also attach themselves to carbonate ions. As more and more hydrogen ions attach to carbonate ions, it prevents marine life from absorbing a mineral called calcium carbonate into their bodies.
Some species of zooplankton with very thin shells known as pteropods are already showing signs of shell deformation from ocean acidification.
Species like crabs, scallops and oysters have hard shells that are made primarily of calcium carbonate.
Seagrasses, seaweeds and algae breathe in CO2 and many of these species will thrive in an ocean with increased acidity and elevated CO2 levels.
95% of a jellyfish’s body is made of water. Lacking shells, skeletons, brains, blood or even a heart, they are virtually unaffected by changes in ocean acidity.
96% of all marine species were wiped our during the Permian-Triassic Mass Extinction – a period sometimes referred to as
“The Great Dying”. Ocean Acidification was one of several major factors responsible for the most severe extinction event in Earth’s history. It took an estimated 10 million years for life to recover.
Ocean acidification was directly responsible for a mass extinction of shelled marine life living on the seafloor known as foraminifera.
Approximately 25% of all marine life spends all or part of their lives in a coral reef ecosystem.