How acidic seas are reshaping the planet

Pacific Northwest, USA: Oyster farms have faced an 80% oyster larvae mortality. This means that millions of dollars worth of food and revenue is being lost due to the heavily reduced amount of oysters in the area.

Contents

The chemistry Effects of the acidification Risks it poses Solutions Conclusion Bibliography

Alaska, USA: Sockeye salmon found in Alaska depend on pteropods for nutrition. These pteropods are rapidly reducing due to the increased acidification of the oceans. Many communities in these areas that rely on marine life for food are now facing a major decrease in their food and source of revenue.(Teicher, S.)

Tanzania, Africa In some villages in Tanzania ¾ of houses fish for food and use those fish as a source for their livelihood. The increasing acidification that threatens the coral reefs in those areas is making the fish and shellfish of the area increasingly scarce.

Haiti, Caribbean and Senegal, Africa: Certain communities in these countries already suffer from malnutrition due to poverty and other factors in some areas. Now these areas are also being affected by ocean acidification. The shell fish and other marine creatures that they rely on for food are rapidly decreasing making it harder to find them and for everyone to get enough to sustain their families.

Ocean acidification is the global decrease in the PH of our ocean and sea water. Carbon dioxide from our atmosphere is being dissolved into our oceans and in turn alters the chemical reactions happening in the water. It decreases the amount of carbonate ions present in our oceans, which many marine creatures use to build their shells and skeletons. Ocean acidification poses a great risk to the livelihoods of many marine creatures and the planet as a whole. In this article I will be discussing how ocean acidification occurs, its effects on our ecosystems and ways in which we can reverse the effects.

The chemistry

A low amount of dissolved hydrogen (H+) ions means that PH is high making it a basic solution, and a high amount of dissolved H+ ions means the PH is low making it an acidic solution. Acidification is when there is an increase in dissolved H+ ions. Now when carbon dioxide(CO2) enters the water a chemical reaction between the carbon dioxide and water occurs. This chemical reaction results in aqueous carbonic acid(H2CO3).

When this carbonic acid is aqueous it undergoes a reaction to form bicarbonate (HCO₃⁻) and aqueous H+ ions. This means that an increase in carbon dioxide creates an increase in H+ ions in the water resulting in an increase of the acidification of our oceans.

All the reactions mentioned above are reversible, so before the industrial revolution the amount of carbon dioxide entering and leaving the oceans was at a stable and balanced amount. The PH of our waters then was at 8.2. Now with the increase in carbon dioxide, the PH of our oceans has fallen to below 8.1. This may not seem like a major rise in the acidity of the ocean, but it in fact is and causes quite a lot of problems for marine life.

Effects of the acidification

The increase in H+ ions directly affects the calcium carbonate(CaCO3) skeleton found on many sea creatures including coral, mollusks, algae, crustaceans, and sea urchins amongst others. The calcium carbonate structure is an ongoing array of calcium(Ca²+) ions and carbonate(CO3²-) ions. This is a solid structure of an alternating array of positive and negative ions. Now when H+ comes along it bonds to the carbonate ions making it a hydrogen carbonate(HCO3-) ion. This hydrogen carbonate is highly soluble in water, so once it is formed it breaks away from the skeleton and dissolves in the water leaving a part of the skeleton exposed. The water then surrounds the calcium ion that was left behind by the carbonate, and causes it to also dissolve in the water. Another H+ ion comes and attaches itself to another carbonate ion and the process repeats itself until the skeletal structure is completely dissolved in the water.

Carbonate ions are extremely essential for the sea creatures to build their calcium carbonate skeleton. The H+ ions take away these carbonate ions and make hydrogen carbonate, and now there is no available carbonate ion for the creatures to build their skeletal structures which greatly reduces calcification. Calcification is the biochemical process of synthesizing a solid calcium carbonate skeleton from the biologically available calcium ions and the externally available aqueous carbonate ions. This just tells us that without the carbonate ions the sea creatures would not be able to create their skeletal structures leaving them exposed and vulnerable to many dangers.

Risks it poses

The sea creatures that rely on the carbonate ions to build their skeletal structures and shells will not be able to do so as there is a decrease in the availability of the carbonate ions. When this occurs it leaves them exposed to increased predation, they may also decrease in size which just makes them even more vulnerable to danger. The shells of these organisms not only help them but also greatly impact other marine life. Pteropods for example have shells that are used as food by krills and whales. With the acidification of our oceans, the shells of these pteropods only last six weeks before they dissolve. It isn’t only the smaller marine life that is feeling the effects of the acidification, squid and fish can also experience a condition called acidosis. Acidosis is the rising of carbonic acid concentration in their body fluids causing problems for the animal in terms of respiration, growth and reproduction.

The abundance of many sea creatures such as pteropods, foraminiferans, and coccoliths is decreasing rapidly. This is forcing the predators of these species to switch their source of food, which then decreases these predator populations as well, and the creatures that then eat those predators are also left without food and the cycle goes on. This all poses a great risk to the food chain of marine life which in turn affects terrestrial life, then it goes back to us humans. Many animals and humans alike rely heavily on marine life for sustenance. It is a major concern of many scientists that many of these marine creatures may possibly go extinct because they simply do not have the time to adapt to these rapid changes. A lot of them are vital to the continuity of the food chain.

Corals, centers of biodiversity in the oceans, are also at risk of being destroyed and disappearing completely if the carbonate ion concentration continues to decline. Due to the carbon dioxide that dissolves in the water going down with cooler denser water, the lower levels of the ocean are naturally more acidic than the more surface level waters. These two layers are separated by a little boundary called the saturation horizon. Tropical coral reefs are rarely ever found below 100 meters, while midlatitude and cold polar corals can be found between 40 to 1,000 meters below. Above the saturation horizon there are enough carbonate ions to support the coral communities. Studies show that since the 1800s the saturation horizon has risen from 50 to 200 meters in the midlatitude and polar waters. This is enough to start threatening the life of the coral communities in these regions. Now with the increasing acidity the saturation horizon will just keep rising to the surface, soon reaching levels that threaten tropical and warmer water corals as well. These warmer water corals are a major food supplier to communities living in those areas. As corals decline, so do the food sources for the people living there.

With the increasing acidification of the ocean, phytoplankton, microorganisms that produce dimethyl sulfide (DMS), a gas which serves as the most significant source of sulfur for our atmosphere, will be at risk. Sulfur is a significant factor in ensuring that some of the radiation coming from the sun is reflected back to space. This reflection of the solar radiation back to space ceases the warming of our Earth’s surface. Now because marine phytoplankton are at risk, DMS production is predicted to decrease by 18% by the year 2100. The Earth’s temperature will then continue to increase, which causes its own array of problems that it will inevitably create for all life on Earth.(Rafferty, & P, J.)

Solutions

There are a couple ways in which we can reduce and reverse ocean acidification. One of the best ways would be to control the amount of carbon dioxide entering our atmosphere. The amount entering our atmosphere is what determines the amount that will enter the ocean. It is important for everyday people and larger industries and companies to reduce their carbon footprint as a whole. Some ways to do that are by reducing food and other wastes, switching to more renewable options in all sectors of life if possible, recycling, reusing and reducing.

Another way in which we can reduce the amount of carbon stored in our atmosphere and in turn prevent the ocean from acidifying is by planting and growing blue carbon ecosystems. It is important to protect these ecosystems as they are extremely helpful in reducing the amount of carbon in the air for many local communities that may be affected by the acidification of the ocean. Some of these ecosystems include mangroves, seagrasses, and salt marshes.

There are also efforts by many scientists that are being made to reverse the effects of ocean acidification. They are working towards ocean alkalinity, which is the opposite of ocean acidification. Instead of acidifying the ocean, it makes the acidified parts more alkaline.

Conclusion

With all the risks of ocean acidification mentioned above, it may seem as though this is a situation that will have severe effects on our ecosystems and planet. That is because it quite literally is a dire situation in which we must take control of before it causes irreversible damage to marine life and in turn our planet as a whole.

The increase in carbon emissions in the last century has caused more than one problem to our planet. Ocean acidification is just one amongst many. It is important to actively use the solutions mentioned above and others to reduce the carbon footprint we leave on the planet. As a collective, if we take these things seriously we can significantly turn the tides in our favour. A healthy planet directly influences our and many other organisms’ health and standards of living. It is imperative that we take immediate steps towards a greater future for our planet and ourselves moving forward.