Ocean acidification

The rate at which ocean acidification will occur may be influenced by the rate of surface ocean warming, because the chemical equilibria that govern seawater pH are temperature-dependent. Greater seawater warming could lead to a smaller change in pH for a given increase in CO₂.

Another effect of global warming on the carbon cycle is ocean acidification.clarify The ocean and the atmosphere constantly act to maintain a state of equilibrium, so a rise in atmospheric carbon naturally leads to a rise in oceanic carbon. When carbon dioxide is dissolved in water it forms hydrogen and bicarbonate ions, which in turn breaks down to hydrogen and carbonate ions. All these extra hydrogen ions increase the acidity of the ocean and make survival harder for planktonic organisms that depend on calcium carbonate to form their shells. A decrease in the base of the food chain will, once again, be destructive to the ecosystems to which they belong. With fewer of these photosynthetic organisms present at the surface of the ocean, less carbon dioxide will be converted to oxygen, thereby allowing the greenhouse gasses to go unchecked.

Steps are being taken to combat the potentially devastating effects of ocean acidification, and scientists worldwide are coming together to solve the problem that is known as “global warming’s evil twin”.

Between 1750 and 2000, surface-ocean pH has decreased by about 0.1, from about 8.2 to about 8.1. Surface-ocean pH has probably not been below 8.1 during the past 2 million years. Projections suggest that surface-ocean pH could decrease by an additional 0.3–0.4 units by 2100. Ocean acidification could threaten coral reefs, fisheries, protected species, and other natural resources of value to society.

Effects of acidificationedit

The effects of ocean acidification can already be seen and have been happening since the start of the industrial revolution, with pH levels of the ocean dropping by 0.1 since the pre-industrial revolution times. An effect called coral bleaching can be seen on the Great Barrier Reef in Australia, where ocean acidification's effects are already taking place. Coral bleaching is when unicellular organisms that help make up the coral begin to die off and leave the coral giving it a white appearance. These unicellular organisms are important for the coral to feed and get the proper nutrition that is necessary to survive, leaving the coral weak and malnourished. This results in weaker coral that can die more easily and offer less protection to the organisms that depend on coral for shelter and protection. Increased acidity can also dissolve an organism's shell, threatening entire groups of shellfish and zooplankton and in turn, presenting a threat to the food chain and ecosystem.

Without strong shells, surviving and growing becomes more of a challenge for marine life that depend on calcified shells. The populations of these animals becomes smaller and individual members of the species turn weaker. The fish that rely on these smaller shell constructing animals for food now have a decreased supply, and animals that need coral reefs for shelter now have less protection. The effects of ocean acidification decrease population sizes of marine life and may cause an economic disruption if enough fish die off, which can seriously harm the global economy as the fishing industry makes a lot of money worldwide.

Ocean acidification can also have affects on marine fish larvae. It internally affects their olfactory systems, which is a crucial part of their development, especially in the beginning stage of their life. Orange clownfish larvae mostly live on oceanic reefs that are surrounded by vegetative islands. With the use of their sense of smell, larvae are known to be able to detect the differences between reefs surrounded by vegetative islands and reefs not surrounded by vegetative islands. Clownfish larvae need to be able to distinguish between these two destinations to have the ability to locate an area that is satisfactory for their growth. Another use for marine fish olfactory systems is to help in determining the difference between their parents and other adult fish in order to avoid inbreeding.

At James Cook University's experimental aquarium facility, clownfish were sustained in non-manipulated seawater that obtained a pH of 8.15 ± 0.07 which is similar to our current ocean's pH. To test for effects of different pH levels, seawater was manipulated to three different pH levels, including the non-manipulated pH. The two opposing pH levels correspond with climate change models that predict future atmospheric CO2 levels. In the year 2100 the model predicts that we could potentially acquire CO2 levels at 1,000 ppm, which correlates with the pH of 7.8 ± 0.05. Continuing even further into the next century, we could have CO2 levels at 1,700 ppm, which correlates with a pH of 7.6 ± 0.05.

Results of this experiment show that when larvae is exposed to a pH of 7.8 ± 0.05 their reaction to environmental cues differs drastically to larvae's reaction to cues in a non-manipulated pH. Not only did if effect their reaction to environmental cues but their reaction to parental cues was also skewed compared to the larvae reared in a non-manipulated pH of 8.15 ± 0.07. At the pH of 7.6 ± 0.05 larvae had no reaction to any type of cue. These results display the negative outcomes that could possibly be the future for marine fish larvae.