Many people are aware that the climate is changing. Carbon dioxide levels have been steadily rising since the start of the industrial revolution with the increase of factories and production. When people think of these facts they generally are thinking of pollution and global warming. While it is true that carbon dioxide is a greenhouse and is likely a factor responsible for global warming, the impacts of carbon dioxide as an acidifier on the world’s oceans are often overlooked. According to Branch et al. from the School of Aquatic and Fishery Sciences, the impact of ocean acidification on primary productivity will greatly impact food webs and ultimately effect the livelihood of humans if it continues to happen at its current rate.
Ocean acidification is the result of increased levels of carbon dioxide in the atmosphere. The ocean is in a constant shifting equilibrium state. Carbon dioxide and water are constantly shifting between their states and carbonate ions, carbonate ions, and hydrogen ions. As more carbon dioxide is introduced the equation shifts more toward the ionized side and as a result the pH lowers. The reason that increased acidity in the ocean is extremely detrimental to a great deal of wildlife but directly impacts calcifiers.
Calcifiers is a general term for are all organisms which create calcium byproducts. These byproducts are typically protective shells which are made out of calcium carbonate. Calcifiers which undergo this process include but are not limited to corals, mollusks, and crustaceans. Although these organisms make up a majority of the calcifiers, there are also many forms of green algae which produce calcium carbonate such as Halimeda. These algae are important because they help produce sediment which acts as a substrate for many oceanic organisms. They are also responsible for creating a great deal of the sediment which makes up sand in coastal areas. With increasing ocean acidity, the process through which calcium carbonate is produced is greatly reduced. The rate at which calcium carbonate can be produced is directly impacted by the amount of carbonate ions in the water. As more carbonate ions are dissolved in the water due to acidification, calcifiers must expend more energy in order to create calcium carbonate. An increased effort to create the calcium carbonate requires the organisms to obtain more energy and generally reduces fitness of the organisms which results in lower survival rates.
Although the increasing acidification will undoubtedly have a large impact on calcifiers and food chains in general, Branch et al. explain that little research has been conducted to investigate. During experimentation, fish during different stages of their life were exposed to increase carbon dioxide levels in order to try and see impacts of future increases in carbon dioxide. In general, the results showed that increased carbon dioxide levels not only impact and impede calcifiers but also have negative results in the developmental and behavioral patterns of fish. Increased levels of carbon dioxide caused the larval stages of several species of fish to not develop properly and also resulted in abnormal behavior. Both of these reduced the survival rate in these species.
The reason that this article is of critical importance is due to the fact that most of the world relies on fishing as a source of income and fish as a source of food. This is especially true in underdeveloped countries where fish is one of the only viable and affordable sources or protein. With the increasing acidity of the oceans, fish and mollusks fitness will continue to reduce resulting in food chains breaking down and also directly impacting humans. Since ocean acidification cannot simply be undone, a conscious effort must be made to reduce carbon dioxide emissions in order to prevent an increased rate of ocean acidification.
Trevor A. Branch, Bonnie M. DeJoseph, Liza J. Ray, Cherie A. Wagner, Impacts of ocean acidification on marine seafood, Trends in Ecology; Evolution, Available online 2 November 2012, ISSN 0169-5347, 10.1016/j.tree.2012.10.001.