Ocean Acidification

Ocean acidification is an emerging concern globally. Over the past few years, there has been a greater focus on the ocean science community on studying the consequences of ocean acidification. According to a new study, with the increasing acidification of world’s oceans due to man-made climate changes such as the burning of fossil fuels, coral reefs are at a greater risk of dissolving. And they could start dissolving before 2100.

“Coral reefs will transition to net dissolving before the end of the century,” an Australian-led team of scientists wrote in the U.S. journal Science. Net dissolving refers to reefs losing more material than they gain from the growth of corals. Much of the carbon dioxide in the atmosphere gets dissolved in the oceans. As the carbon dioxide content increases in the ocean, the pH of water reduces, leading to acidification.

This ocean acidification will pose a threat to the sediments which are the building blocks for reefs. Carbon dioxide forms a weak acid in water and threatens to dissolve the reef sediments, which constitute shredded bits of corals and other carbonate organisms that accumulate over thousands of years, according to the journal. Moreover, with acidification, corals are unable to absorb the carbon dioxide which they require to maintain their skeletons from the seawater. These tiny living creatures feel stressed from ocean temperatures, pollution, and overfishing. Thus, if no measures are taken to reduce these greenhouse gas emissions into the atmosphere, ocean acidification would increase. This will lead to more and more corals being destroyed. The study also said that sediments are 10 times more likely to be affected by acidification than corals.

Coral animals will be able to keep growing and replenish reefs long after sandy sediments begin to dissolve, according to Bradley Eyre, lead author of the study from Southern Cross University. “This probably reflects the corals’ ability to modify their environment and partially adapt to ocean acidification whereas the dissolution of sands is a geochemical process that cannot adapt,” he wrote in an email.

The study said that it is uncertain whether the whole reef will erode once the sediments become net dissolving, and whether reefs will undergo catastrophic destruction or just a slow erosion. It is also unknown if the dissolution of sediments could be a lasting threat to entire islands from the Pacific to the Caribbean.

As per the report, some reef sediments have already started to dissolve. An example includes the Kaneohe Bay in Hawaii, where other pollutants are contributing to the process. Many studies show that ocean acidification severely affects not only corals but also the overall ocean life, including creatures such as snails, urchins, oysters, lobsters, and crabs. Contrarily, it was found in a study that acidification might help in the growth of some plants such as kelp and seaweeds.

Steps have been taken by few nations to protect its marine biodiversity. For instance, the Aldabra Atoll, a UNESCO World Heritage Site, is home to numerous rare species such as giant tortoises and sea cows. However, over-fishing caused their numbers to roll down. Recently, a bill was signed by the nation’s government to ban every kind of human activity including fishing and petroleum exploration in the waters around Aldabra. The island of Seychelles also announced its pioneering marine conservation plan, where it is designating about a third of its waters as protected areas, with the goal to maintain the longevity of its unique biodiversity.

Well, the crux of the matter is that if we continue to produce carbon dioxide at the current pace, the high level of gas will reduce ocean surface pH to a level that could dissolve coral skeletons and may cause reefs to fall apart. And the absence of coral reefs will lead to the loss of vital habitat. Thus, the health of coral reefs and many marine organisms rely on our ability to reduce our carbon dioxide emissions. Hence, factors such as population, energy sources and how much energy we use, and what new technologies we create will determine the carbon dioxide emissions.