Today, the devastating effects of rising man-made carbon dioxide (CO2) emissions, more technically called anthropogenic CO2emissions, are becoming increasingly evident in our beautiful blue ocean waters in the form of ocean acidification. Fortunately, the mangrove, often called a “Super tree,” might be able to counteract ocean acidification and become the protector oceans, marine life and humanity need.

Mangroves

For many years, the burning of fossil fuel for transportation and electricity, production of cement, destruction of forests, and other human activities have resulted in a release of alarmingly high levels of CO2 into the air. Normally, CO2 in the air is absorbed by the ocean, where it dissolves and forms an acid, helping maintain an equilibrium. And, as more CO2 is released, the amount of CO2 dissolving into the ocean and forming an acid increases too. This acid then changes the pH of seawater, resulting in higher acidity. This harmful and ongoing decrease of ocean water pH is called ocean acidification (Caldera and Wickett, 2013).

Of course, seawater in vast blue oceans plays many very important roles in the maintenance of life on Earth. When working in tandem with sediments and the atmosphere, seawater can function as a carbon reservoir, which helps maintain carbon in equilibrium. However, ocean acidification is disrupting this balance by decreasing the availability of calcium carbonate (CaCO3). A decline in CaCO3 can become detrimental to marine organisms that require this molecule to form shells and structures necessary for their survival (Ocean Chemistry, 2013). Corals, for example, use CaCO3 as building blocks that form colorful reefs, landscaping the ocean floor with underwater gardens. Sadly, scientists are observing that the present rise in ocean acidity is slowing down the calcification rate of corals leading to reduced growth rate. This inability to grow is affecting the preservation of corals’ healthy structures and the marine life forms they support (National Oceanic and Atmospheric Administration, 2017).

Ocean acidification may also affect development of many marine organisms. The sea urchin, for example, spends part of its life cycle as larva and the larva cannot digest food properly in acidic conditions (Stumpp et al., 2013). This decrease in ocean pH also causes organ damage in Atlantic Herring larvae (Frommel et al., 2014).

In fact, we do not know the exact extent of damage that increased atmospheric CO2 and ocean acidification will have on ecosystems around the Earth in the near and far future. Scientists predict that “unabated CO2 emissions over the coming centuries may produce changes in ocean pH that are greater than any experienced in the past 300 million years, with the possible exception of those resulting from rare, catastrophic events in Earth’s history” (Caldeira and Wickett, 2003).

So, what may be nature’s solution to ocean acidification? Mangrove forests. Mangroves are peculiar trees and shrubs that can buffer the ongoing ocean acidification. These trees can be found in coastal areas and have special aerial roots anchored in carbon-rich soil and thrive in salty water. It is these roots that have evolved to effectively metabolize organic matter from the surrounding oxygen-poor soil to release alkalinity into surrounding water, buffering the decreasing pH caused by increased atmospheric CO2 in nearby water, and helping create an equilibrium in the open ocean. James Z. Sippo and his research team have studied how important the mangrove input of alkalinity is to ocean acidification. In their study of the effect of alkalinity output from mangrove tidal creek in Australia, Sippo et al. found that water near the mangroves has a higher pH (8.1) compared to seawater far from the coastal mangroves (pH 7.3). They also estimated that mangrove forests export up to 4.2 teramoles (1 teramole = 1000000000000 moles) per year of alkalinity worldwide. This mangrove-generated alkalinity could certainly counteract increasing acidity in ocean water, which has showed a decrease in pH of 0.1 units since the beginning of the industrial age, and currently absorbs about one third of all man-made CO2 emissions (Caldeira and Wickett, 2003). Thus, the alkalinity released by mangroves effectively contributes to a pH increase in nearby ocean water and solidifies the mangrove as an effective buffer for ocean.

For many years we have known mangroves, usually found in tropical and subtropical coasts, as invaluable ecosystems that help support many living organisms including small fish, snails, oysters, worms, insects, birds and crocodiles. Mangrove trees also help humankind in different ways. Mangroves are sources of food and wood and are major tourism attractions. They also protect coastlines from extreme weather (Wilson, 2017). Thus, it is imperative we ensure their survival.

Unfortunately, this magnificent life-form is being threatened. Human activity such as pollution, coastal development, and agriculture, etc., has hurt their survival and has caused a significant decline in mangrove forest areas (Thomas et al., 2017 and Wilson, 2017).

So, what can we do to protect these remarkable buffers? Many communities around the world have become organized to replant mangroves and educate others about their sustainable use. The General Conference of UNESCO declared July 26th as the International Day for the conservation of the Mangrove Ecosystem, helping to start a global conversation on how to save the mangrove, a crucial protector of human life.

Each of us can contribute to the preservation of mangroves by becoming involved in mangrove conservation and restoration groups, learning about the qualities of these buffers, teaching others about their immense value, and simply, by being nicer to our home, planet Earth!

These are a few organizations and resources to get you started on saving the mangrove:

References:

Caldeira, K., & Wickett, M. E. (2003). Anthropogenic carbon and ocean pH. Nature, 425, 365.

Frommel, A. Y., Maneja, R., Lowe, D., Pascoe, C. K., Geffen, A. J., Folkvord, A., Piatkowski, & Clemmesen, C. (2014). Organ damage in Atlantic herring larvae as a result of ocean acidification. Ecological Applications, 24(5), 1131-1143.

Marine Education Society of Australasia. “Animals of the mangroves.” Mangroves of Australia. Retrieved March 23, 2018

National Oceanic and Atmospheric Administration. (2017). How does climate change affect coral reefs? National Ocean Service website. Retrieved March 23, 208.

Ocean Chemistry. (2013). Retrieved March 26, 2018.

Thomas, N., Lucas, R., Bunting, P., Hardy, A., Rosenqvist, A., & Simard, M. (2017). Distribution and drivers of global mangrove forest change, 1996-2010. PLoS One, 12(6): e0179302.

Sippo, J. Z., Maher, D. T., Tait, D. R., Holloway, C., & Santos, I. R. (2016). Are mangroves drivers of buffers of coastal acidification? Insights from alkalinity and dissolved inorganic carbon export estimates across a latitudinal transect. Global Biogeochem. Cycles, 30, 753-766.

Stumpp, M., Hu, M., Casties, I., Saborowski, R., Bleich, M., Melzner, F., & Dupont S. (2013). Digestion in sea urchin larvae impaired under ocean acidification. Natural Climate Change 3, 1044-1049.

Wilson, R. (2017). Impacts of Climate Change on Mangrove Ecosystems in the Coastal and Marine Environments of Caribbean Small Island Developing States (SIDS). Caribbean Marine Climate Change Report Card: Science Review, 60-82.

Fernanda Ruiz is a science content writer at Gold Biotechnology. She holds a bachelor's of science in biology from St. Mary's University and a PhD in molecular biology from Baylor College of Medicine.