Why we should protect mangroves

The importance of mangroves and their growing role in climate change discussion

In a previous blog, I mentioned some ecosystems that have proven critical to maintaining safe levels of atmospheric carbon dioxide. One ecosystem I mentioned is the mighty mangrove. In this post, we will explore the importance of mangroves, their role in climate change, and why it is crucial to protect them.

Sourced from https://www.nature.org/en-us/newsroom/new-mangrove-insurance-feasibility-report/.

A mangrove is a tree or shrub that lives in a coastal intertidal zone (the area where land and ocean meet). Generally, scientists use the word mangrove or phrase mangrove forest to describe an ecosystem/community of individual mangrove plants and organisms that have evolved to live and work together. Mangroves can be found along coastlines across the globe, thriving in tropical and subtropical temperatures. They are able to live under the harsh conditions of a constant flow of salty water, conditions that nearly every over plant would die in, due to their evolved ability to filter out the majority of salt they absorb and excrete it back into their ecosystem.

Figure depicting where mangrove species can be found globally. (Deltares, 2014)

Mangroves have a lot of abilities, one of the most important being their ability to absorb carbon dioxide and store it for long periods of time. During photosynthesis, mangroves absorb carbon dioxide from the atmosphere. In this process, they produce O2 and incorporate the leftover carbon in their biomass (leaves, branches, stems), root systems, and the surrounding soil. When mangroves die, their carbon rich biomass is incorporated into the soil and remains stored there for long periods of time (up to thousands of years!). Compared to other plants, mangroves remove carbon dioxide from the atmosphere about four times more efficiently. Their efficiency cannot be understated: despite making up less than 2 percent of marine environments, mangroves account for 10 to 15 percent of carbon burial (removing carbon from the short-term carbon cycle and burying it in sediments). This characteristic of mangroves has earned them the title of a 'carbon sink', a process that stores a lot of carbon.

Aside from absorbing and storing large amounts of carbon, mangroves provide many different services to both humans and animals. Mangroves trap sediments flowing from water in their dense root systems. This stabilizes coastlines and reduces erosion caused by storm surges, currents, waves, and tides. In this way, they act as a natural ‘buffer’ for surrounding communities and animals against increasing natural disasters.

Many animals turn to mangroves for food and shelter because their intricate root systems create a protected environment and provide diverse food sources. In particular, mangroves serve as a great nursery for both wild and commercial fish species. Many of the oceans’ fish get their start in mangroves.

Humans greatly benefit from this natural fish nursery and many local communities have come to depend on the services that mangroves provide. In addition to using mangroves for commercial fisheries, mangroves provide humans with fruit, medicines, fiber, cleaner water, and wood.    

Sourced from https://kids.frontiersin.org/articles/10.3389/frym.2022.812948.

You may be thinking: Well, this is great! Humans have a built-in carbon sink, disaster buffer, and animal sanctuary already made for us! This takeaway is the same one that many people share today. However, opinions on mangroves in the past and some current evaluations on the value of these ecosystems differ. In the past, mangroves were often categorized as useless swamps that weren’t of any value to humans. This led to mangroves being cleared for coastal developments, agriculture, shrimp farms, timber, and urban expansion. Despite having more knowledge on the importance of mangroves, the clearing of these ecosystems continues today for many of the same reasons. Mangroves are not only harmed through direct clearing, they are also harmed by herbicide runoff, sea level rise, and overexploited fisheries. These threats already sound bad, but they become even more catastrophic when factoring in the fact that in the same way mangroves store a lot of carbon they will also release massive amounts of carbon into the atmosphere when destroyed. 

Researching this topic has taught me that it is critical to preserve and protect existing mangrove ecosystems not only for the services they provide, but also to avoid releasing even more carbon into the atmosphere. Though there is value in transitioning to renewable energies and reducing emissions, we have to put effort into conserving existing systems that benefit our climate and communities. We have to recognize the value in protecting existing systems that have stabilized the planet for millenniums. 

-- Sophie Wassef

Sources