By: Mohamed Sahr (Mashmarrow)
Essentially, mangroves which are shrubs or trees that grow in coastal salt water have the stimulating focus to effectively reduce water level during an extreme event like hurricane and typhoons. They provide palatable roles to the ecosystems and its habitats. These natural-based defences serve as protective covering beneath the rivers, streams, sea including the Atlantic Ocean with the free movement and survival of a number of marine species.
They also serve as a buffer between marine and terrestrial communities and protect shorelines from damaging storm, hurricane winds, waves, and floods. Mangroves also help prevent erosion by stabilizing sediments with their tangled root systems. They maintain water quality and clarity, filtering pollutants and trapping sediments originating from land. However, the importance of mangroves does not only limit to marine life and communities but also boils down to biodiversity, livelihood, water, carbon storage, coastal defence and materials.
Foremost, mangroves are biodiversity and livelihood hotspots. They provide nesting and breeding habitat for fish and shellfish, migratory birds, and sea turtles. An estimated 80% of the global fish catch relies on mangrove forests either directly or indirectly. This is according to a study done on mangroves and their role in coastal protection in 2022. The study shows that healthy mangrove ecosystems mean healthy fisheries from which to fish, and healthy land on which to farm.
On the other hand, mangroves are essential to maintaining water quality. With their dense network of roots and surrounding vegetation, they filter and trap sediments, heavy metals, and other pollutants. This ability to retain sediments flowing from upstream prevents contamination of downstream waterways and protects sensitive habitat like coral reefs and seagrass beds below. In addition, it is not a gainsaying that mangroves are the first line of defense for coastal communities. They stabilize shorelines by slowing erosion and provide natural barriers protecting coastal communities from increased storm surge, flooding, and hurricanes.
Notwithstanding, in terms of carbon storage, mangroves bring about a toll of “sequester carbon at a rate two to four times greater than mature tropical forests and store three to five times more carbon per equivalent area than tropical forests” like the Amazon rainforest. This means that conserving and restoring mangroves is essential to fighting climate change, the warming of the global climate fueled by increased carbon emissions. In connection with the undermentioned, mangroves are purposeful materials that perform traditional, local and scientific important to the country in general. This is to say, communities have historically used mangrove wood and other extracts for both building and medicinal purposes etc.
Even though there are host of benefits derive from mangroves in Sierra Leone, but they also have bedeviled compass that is hanged on the country like a moist towel. Apparently, in an article published by David Goodman who was a freelance journalist in 2020, he reclaims how the loss of mangroves has affected the country especially in Gbongboma a village that is located on Sherbro Island in the Sherbro River Estuary, which is homed to the greatest concentration of mangroves in Sierra Leone. He stated that mangroves play a vital role in food security and in the local economy because they are a breeding ground for fish. Therefore, the loss of mangroves reduces spawning grounds, leading to further depletion of fish. Because the trees grow near the water’s edge and have a dense, woody root system, they also protect against storm surges, coastal erosion and flooding, making them all the more important because communities of the Sherbro River Estuary are extremely vulnerable, given their location and the physical threat of sea level rise.
Aside from all the fantastic flavor mangroves drive along with to communities and marine life and the pinpointed motions of David Goodman in his article in 2020, there have been another broader spectrum in the annals of science. In that regard, Scientists from the National Oceanography Centre (NOC) in 2023 have made a breakthrough discovery that could lead to significantly improved coastal defences using mangrove trees. While mangroves provide a layer of natural protection, the study also showed that, in order to utilize mangrove-based defences, location-specific numerical simulations are essential to effectively design them. The research was conducted across the Pearl River Delta in the South China Sea which is home to several Chinese “mega-cities” such as Hong Kong, Shenzhen, and Guangzhou. All three cities are currently experiencing huge growth which comes with an expansion of areas vulnerable to flooding.
Mangroves can provide coastal protection in the tropical, subtropical, and warm-temperate world. In the UK, other natural habitats, for example saltmarshes, could provide similar coastal protection benefits, but they are still poorly studied.
Dr Michela De Dominicis, Senior Research Scientist in the Marine System Modelling Group at the National Oceanography Centre and lead author on the study, said: “This is an important new study that helps in planning out effective nature-based coastal defences. Mangroves are a vital natural resource at our disposal to protect communities. Even if mangroves on their own do not fully block water flow, they can reduce the extent of the flooding or they can be combined with traditional flood defences such as seawalls and levees, allowing for lower structures.”
The study is especially valuable given that existing research into the controlling factors of how coastal vegetation can reduce extreme water levels is unclear. This means that until now, there has been a limited implementation of using nature-based coastal defences in delta areas housing large cities.
Overall, the study found how effective mangroves are as a nature-based tool to protect coastal areas, as well as highlighting the need for location specific predictions to be made prior to extensive restoration efforts. The study, which was the first of its kind, will inform future research that will consider the amount of storm surge reduction that would make implementation of mangroves a viable investment, as well as considering the other benefits that mangroves offer such as carbon storage, biodiversity and the prevention of coastal erosion.
Dr Michela De Dominicis added: “This study clears up how mangrove forests change the movement of water in a complex delta plain on a local scale and in areas further away. Mangrove forests are one of the most powerful natural tools we have to protect coastal communities from rising sea levels and severe storms.”
