By now most people know that the levels of carbon dioxide in the atmosphere has been rapidly increasing, but what is all that CO₂ doing to our oceans? The ocean absorbs about 30% of the CO₂ that is released into the atmosphere. When the CO₂ dissolves into the ocean and combines with seawater, it forms carbonic acid that then breaks into hydrogen ions and bicarbonate ions. The increase in hydrogen ions increases the acidity of the ocean and decreases the pH. Over the years, the pH level of ocean water has decreased by 0.1 pH units which is equivalent to a 30% increase in acidity. The ocean’s current pH level is about 8.1, but as the acidity of the ocean continues to rise, we are continuing to harm marine life and human life.
Ocean organisms that need to create hard shells or skeletons, such as oysters, snails, and coral, are greatly impacted by ocean acidification. These creatures create shells and skeletons by combining calcium and carbonate from the water but since there are so many hydrogen ions in the ocean the carbonate ions bond with those instead. If carbonate ions are not available for the life forms that use them, they cannot build their shells and skeletons or keep them healthy. If the pH levels are low enough, shells and skeletons can dissolve. A study done on pteropod shells showed how detrimental seawater can be to these organisms in the future. “When pteropod shells were placed in sea water with pH and carbonate levels projected for the year 2100, the shells slowly dissolved after 45 days.” If we do not take action on climate change now, this study will become reality.
Fish are also feeling the effects of the increased acidity of the ocean. When the water around a fish has a lower pH, it’s cells will try to balance with the water by taking in carbonic acid which then changes the pH of the fish’s blood. After this happens, the fish will have to use its energy to get rid of the excess acid through its gills, kidneys, and intestines in order to bring its body chemistry back to normal. This takes away the energy that the fish needs to do other things that are necessary to keep the fish alive. Acidic waters affect different fish species in different ways, but the harm being done extends beyond aquatic life. Communities who rely on fish as a source of food or income will have to face the repercussions of the damage we have done to our oceans.