Disasters At Sea: Mangrove Forest Degradation
- Emily Eliese Cohen
- 4 hours ago
- 6 min read
Introduction
A story about forests may seem unrelated to marine biology, but there is one unique tree that actually plays a critical role in supporting marine life. Mangrove trees are tropical plants that grow in wet soil frequently submerged in saltwater by the tides. Their “prop roots” branch down into the water providing habitat and nursery grounds for many marine organisms. Mangroves protect shorelines by absorbing waves and preventing erosion. They are also efficient carbon sinks, yet despite all these benefits to both ocean life and people, they face degradation from numerous threats. In this article we will dive into what those threats are and what’s being done to restore this vital marine ecosystem.
The Disaster: Mangrove Loss
Half the world’s mangrove provinces are considered threatened and between 2001 and 2012 the world lost 35-97 square miles of mangrove forest every year. The greatest threats that mangrove wetlands face are from farming/aquaculture, natural disasters, climate change, coastal development, and invasive species.
Shrimp farming accounts for 35% of mangrove loss. In the 1980s and 90s, global demand for shrimp dramatically increased and mangrove forests were cleared to make room for shrimp pools in Southeast Asia and Latin America. Since then, through intensified industrialization, shrimp farming has become a 10 billion dollar industry. The majority of the shrimp produced is exported to the United States, Japan, and Europe. Meeting this demand not only directly contributes to mangrove deforestation as trees are cut down and cleared away, but the farms also use chemicals that wind up polluting the surrounding environment. Mangrove ecosystems nearby shrimp farms are exposed to pesticides and antibiotics. Additionally, shrimp farms can affect the hydrology of the area, interfering with tidal regimes and saltwater balances.
Natural disasters are another major threat to mangrove ecosystems. Hurricanes and tsunamis both damage mangroves by uprooting trees with strong winds and forceful waves. In some instances, storms can wipe out an entire forest. As climate change progresses, we are expected to see more frequent and intense storms. Mangroves are phenomenal storm barriers, but as they shield the coast from potential storm damage, the impact they absorb can destroy them too.
Beyond increasing storm intensity, climate change further threatens mangroves by contributing to sea level rise. As sea level rises and beaches shrink, mangrove forests will be flooded. While previous changes to sea level have led mangrove forests to shift further inland, today’s coastal development blocks such migration. Furthermore, mangroves rely on mud buildup to shift inland and today’s buildup rate is not fast enough to compensate for the rate of sea level rise. In the Sundurabans (the world’s largest mangrove forest located in India), 71% of the mangrove forested coastline retreats 200 meters every year.
Coastal development not only blocks mangrove forest migration, but it also contributes to mangrove deforestation and releases the carbon stored by mangrove forest sediment. Mangroves are highly efficient carbon sinks storing carbon in their biomass and in the soil beneath them. During construction when sediment is disturbed, the carbon stored in it is re-released back to the atmosphere. Deforestation and development not only contribute to emissions but they also limit carbon sequestration capacity.
Finally, invasive species also threaten mangrove forests. Invasive species are non-native species that when introduced to the environment threaten the endemic species of the area. For mangroves, there have been multiple cases of invasive species threats. In China, a marsh grass originally introduced in 1979 to combat erosion eventually spread to choke out mangroves in the area. In Texas, an antelope called nilgai introduced in the 1930s as hunting game began eating mangrove leaves.
All of these various threats have led to significant loss of mangrove forests around the world, and when mangroves disappear, the loss goes far beyond the trees themselves to hurt animals, people, and the planet.
Impacts
There are three main benefits that mangroves provide: (1) they are a habitat and nursery for marine organisms, (2) they protect coastlines, and (3) they are carbon sinks. With the loss of mangroves comes the loss of all these major benefits.
Mangroves uphold an incredibly productive and diverse ecosystem of both aquatic and land species. In the branches of the tree there are birds, monkeys, and insects. In the root systems beneath the water there are fish, amphibians, and invertebrates. Crabs, shrimp, and fish use the mangrove root systems for protection in their vulnerable juvenile years before migrating to the open sea. Of commercial fish species, 30-80% of them rely on mangroves either as a nursery or habitat. A loss of one square mile of mangrove forest causes a loss of about 275,000 pounds of fish per year.
By absorbing waves and blocking wind, mangroves protect coastlines from both storms and erosion. In fact, mangroves provide 855 billion dollars worth of flooding protection worldwide. When mangrove forests disappear, they leave coastal communities vulnerable which is especially dangerous as climate change brings stronger storms.
Lastly, mangroves are an example of blue carbon – that is, carbon captured by ocean and coastal ecosystems (other examples include seagrasses and salt marshes). Mangrove soils absorb over 6 billion tons of carbon globally. At the same time, mangrove destruction has released 122 million tons between the year 2000 and 2015.
Recovery
Conservation and restoration efforts are ongoing, however, doing so is not as straightforward as just planting trees. Many restoration projects fail and replanted mangrove trees do not survive. Collaboration with local communities and implementation of local ecological knowledge is necessary for restoration success. Best practices require working within the natural landscape and utilizing historic wisdom to bring the ecosystem back to its former state.
Sustainable practices in and around mangrove ecosystems are also important. In some places, people are implementing sustainable fishing and aquaculture, switching away from logging practices, and introducing alternative livelihood options such as mangrove beekeeping. Local involvement is vital to ensuring the long-term preservation of mangrove forests.
The Global Mangrove Alliance (GMA) is a worldwide collaboration (coordinated by Conservation International, The Nature Conservancy, World Wildlife Fund, Wetlands International, and The International Union for Conservation of Nature) that aims to protect and restore mangrove ecosystems. With over 100 members in more than 40 countries, GMA has already restored 65,000ha of mangroves.
Conclusion
Yearly mangrove loss rates have begun to slow down, thanks to continued protection and restoration efforts, but the threats mangroves face have far from disappeared. On this year’s World Mangrove Day, July 26th, it’s important to remember the vital role of this fascinating coastal tree that faces many disasters at sea.
Citations / Directories
Citation No. 1: “What is a Mangrove?”, Written by Unknown, Published on December 13th, 2024. Published by Florida Department of Environmental Protection. Retrieval Date: June 27th, 2026 https://floridadep.gov/water/submerged-lands-environmental-resources-coordination/content/what-mangrove#:~:text=Mangroves%20are%20tropical%20plants%20that,mangroves%20found%20throughout%20the%20world.
Citation No. 2: “Mangroves”, Written by The Ocean Portal Team, Published on Unknown Date. Published by Smithsonian Museum of Natural History. Retrieval Date: June 27th, 2026 https://ocean.si.edu/ocean-life/plants-algae/mangroves
Citation No. 3: “Threats to Mangroves”, Written by Unknown, Published on Unknown Date. Published by The Mangrove Action Project. Retrieval Date: June 28th, 2026 https://mangroveactionproject.org/wp-content/uploads/2024/06/Threats-to-Mangroves.pdf
Citation No. 4: “State of the World’s Mangroves Executive Summary”, Written by Unknown, Published in 2024. Published by the Global Mangrove Alliance. Retrieval Date: June 28th, 2026 https://tnc.app.box.com/s/hw1cpvdwikibvpw4swh7lzata9nckva4 (6/28)
Citation No. 5: “Farmed Shrimp”, Written by Unknown, Published on Unknown Date. Published by World Wildlife Fund. Retrieval Date: June 28th, 2026 https://www.worldwildlife.org/our-work/oceans/sustainable-seafood/farmed-seafood/farmed-shrimp/
Citation No. 6: “Tigers under threat from disappearing mangrove forest”, Written by John Vidal, Published on January 29th, 2013. Published by The Guardian. Retrieval Date: June 28th, 2026 https://www.theguardian.com/environment/2013/jan/29/sunderbans-disappearing-mangrove-india-bangladesh
Citation No. 7: “Threats to Mangroves”, Written by Unknown, Published on Unknown Date. Published by Environmental Law Alliance Worldwide. Retrieval Date: June 28th, 2026 https://elaw.org/mangroves-threats
Citation No. 8: “What is Blue Carbon?”, Written by Unknown, Published on June 16th, 2024. Published by NOAA. Retrieval Date: June 28th, 2026 https://oceanservice.noaa.gov/facts/bluecarbon.html
Citation No. 9: “Carbon Storage and Sequestration”, Written by Unknown, Published on Unknown Date. Published by Mapping Ocean Wealth. Retrieval Date: June 28th, 2026 https://oceanwealth.org/ecosystem-services/carbon/
Citation No. 10: "Mangroves save $855 billion in flood protection globally, new study shows”, Written by Mike Peña, Published on December 5th, 2024. Published by UNDRR. Retrieval Date: June 29th, 2026
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