Ocean Acidification and its Effects

Two-thirds of the earth’s surface is covered by oceans that play a naturally significant role in the earth’s cycle.

It is argued that the oceans represent the largest active carbon sink. In fact, over 48 percent of the carbon released to the earth’s atmosphere through fossil burning is regulated by the ocean. It is imperative to understand that of the three places that carbon is regulated and stored, i.e. land, oceans and the atmosphere, almost 93 percent is takes place in the oceans.

Therefore, as our oceans begin to face yet another threat because of the uptake of anthropogenic carbon dioxide, marine organisms as well as ecosystems will have to bear the grave consequences. Gaylord et al. (2011) claim oceans have absorbed approximately 525 billion tons of anthropogenic carbon dioxide from the earth’s atmosphere in the past twenty years. Despite the fact that this trait has immensely benefited mankind by reducing greenhouse gas levels, the immense absorption of carbon dioxide by the oceans has started to take a toll on the geochemical and biological processes of the oceans.

Understanding the Ocean Cycle Jutterstrom & Anderson (2010) argue that when anthropogenic carbon dioxide is absorbed by seawater, a chemical reaction that reduces seawater pH takes place. The reaction of carbon dioxide and seawater is called ocean acidification. This reaction is primarily controlled by circulating currents, ocean surface currents and other biological processes such as respiration and photosynthesis. Scientists contend that the amount of carbon dioxide being dissolved in the ocean lowers the pH; therefore, reducing the availability of carbonate ions and also lowers the saturation state of the main carbonate minerals that enhance shell-formation. Feely et al. (2006) asserts that both climate change and ocean acidification result from excessive dumping of carbon into the atmosphere via human activities.

Scientists are of the opinion that if the current trend continues, then the average pH of the oceans might go down by 0.5 by the year 2100 (Gaylord et al., 2011). What worries experts is the fact that ocean acidification is an irreversible process since peoples’ efforts to reduce ocean acidification through artificial means have been futile. However, all is not lost because reducing the amount of carbon dioxide that mankind emits to the atmosphere is the only practical way of minimizing the long term changes and risks to the oceans.

Regions of the ocean that will be affected The prime areas that will be affected by ocean acidification are deep water and high-altitude regions, where carbonate levels are low. As the carbonate saturation horizons in the oceans become shallower and ocean acidification continues, the surface waters in high latitude areas will be under-saturated with respect to aragonite (Jutterstrom & Anderson, 2010). It is believed that these occurrences will affect many calcareous organisms such as foraminifera, pteropods, and coccolithophores in the productive surface area. It is imperative to understand that these organisms play a vital role in cycling carbon from the oceans’ surface to deep oceans. Apart from the high regions, the surface waters of many oceans will also be affected by ocean acidification. This will result from an increase of carbon dioxide levels, which is caused by the functioning and composition of various ecosystems.

Coral reef ecosystems that can be found in the waters of subtropical and tropical regions are also affected by ocean acidification. Coral reef ecosystems are not only reproductive, but also the most diverse marine ecosystems that support thousand of people directly through the continual harvesting of the coral reefs. These precious ecosystems, which can be found in several developing nations, will diminish as a result of reduced calcification rates. Gaylord et al. (2011) contend that a reduction in calcification rates will lead to the growth of fragile skeletal structures and at a slower rate.

It is believed that the oceans may loose more of their reef areas due to erosion that is caused by reduced calcification together with coral bleaching. Ocean Acidification and Marine Life By definition, all marine animals are adapted to their environment. Unfortunately, changes in the ocean chemistry, particularly hasty modifications like ocean acidification have both direct and indirect impacts on these organisms as well as their habitats (Guinotte & Fabry, 2009). Direct impacts of ocean acidification include the effect of increased carbon dioxide concentration and acidity that might affect the different stages of the life cycle.

Indirect effects may arise from the changes in the composition or availability of nutrients due to an increase in acidity.