Ocean Acidification

Ocean Acidification (By: Priscilla Velez)

The Earth’s oceans have a specific acidity level that is required for supporting and maintaining marine life. But, as a result of human activity, oceans are no longer able to maintain this acidity. Research has proven that there has been a 25% increase in ocean acidity. Prior to human activity, the pH of the ocean averaged at 8.2. Currently it is approximately 8.1. This increase in acidity threatens marine life.

What is Ocean Acidification?

Ocean acidification is an increase in the acidity of the ocean.

How and Why is it Occurring?

Technically, as a part of the carbon cycle, the process by which carbon moves around air, land, and sea, the ocean absorbs carbon dioxide from the atmosphere. When carbon dioxide is absorbed into the ocean, it dissolves, and is made readily available to marine life. Some sea animals use the dissolved carbon dioxide to carry out photosynthesis, whereas some sea animals will combine the carbon dioxide with oxygen and calcium to form shells and corals.

The ocean also serves as a carbon sink, meaning that it absorbs more carbon that it releases back into the atmosphere. This is actually beneficial as it slows the process of global warming by decreasing the amount of greenhouses gases in the atmosphere.

However, as a result of the large amount of carbon dioxide present in the atmosphere, the ocean has been absorbing more amounts of carbon dioxide than it should be. To be exact, research has shown that oceans absorb a third of human-induced carbon dioxide emissions. That is about 22 million tons of carbon dioxide a day! This excessive intake of carbon dioxide increases the acidity of the ocean.

How Ocean Acidification Affects Marine Life:

The exact effects of ocean acidification on marine life is still being thoroughly researched. Nonetheless, some severe effects have been brought to light.

- Coral Reefs: Corals use calcium carbonate to form coral reefs. Coral reefs are important as they not only provide a shelter and habitat for corals, but also for many other marine organisms. Acidification affects and limits the growth of corals. Specifically, acidification corrodes existing corals, slows growth of new corals, and causes new corals to be weaker, making them more susceptible to being eroded. Coral larvae living in acidic water may have difficulty in finding an area to settle in, thus preventing them from reaching adulthood.

-Oysters/Mussels/Clams/Urchins/Starfish:  Shelled sea animals, such as mussels, clams, urchins, and starfish, will have trouble building their shells as a result of the increase in acidity. The shells of urchins and starfish will be much more weaker, making them more likely to be crushed or eaten. Mussels, which use their byssal threads to attach themselves to rocks, especially during waves, will not be able to strongly hold on in acidic water. Oysters are rapidly dying because acidic water dissolves their growing shells. The loss of these animals will severely affect the food chain as many other animals depend on them for food.

-Zooplankton: Zooplankton are crucial to marine environments because of their role in the food chain and the carbon cycle. Foraminifera, a kind of zooplankton that uses calcium carbonate to build their shells, was found by an experiment to be unable to stand high acidity. Those in tropical areas are expected to become extinct by the end of the century. Pteropods, another type of zooplankton, are dissolving.

-Plants/Algae: Plants and algae have been found to actually thrive in acidic conditions. However. though plants may not be in danger from ocean acidification, they are in danger from polluted water. The effect of polluted water is so severe, that the thriving of plants from acidification will not compensate for the loss of plants by means of polluted water.

-Fish: The cells of fish will take in carbonic acid to achieve balance, or isotonic conditions. This intake of carbonic acid will change the pH of fish blood, a condition known as acidosis. Acidification may also slow fish growth. Clownfish in acidic conditions were proven to not only fail from fleeing from noise, but were unable to find their way back home. The exact effects of acidification on fish is still being researched, and may vary between different species of fish.