Mangroves Aren’t Mangos!

This year’s Climate and Society class is out in the field (or lab or office) completing a summer internship or thesis. They’ll be documenting their experiences one blog post at a time. Read on to see what they’re up to.

Souvik Chatterjee, C+S ’17

Growing up, I never knew what mangroves were. In fact, whenever someone mentioned them, I thought they were talking about mangos. But of course they’re not tropical fruit. They’re coastal plants that live in the transition zone between the ocean and land and offer a wealth of services for both people and the environment. They are crucial in the fight against climate change.

Mangroves can contribute to disaster risk reduction in coastal areas by reducing the energy of waves and storm surge flooding, playing a key role in coastal adaptation as storms intensify and seas rise. Mangroves also help mitigate climate change by sequestering an incredible amount of carbon. They act as nurseries for fish which benefits coastal communities and the commercial fishing industry, especially important since the world’s fisheries are severely overfished. Mangroves also promote biodiversity, improve water quality and prevent coastal erosion.

Mangroves (Source: Flickr/timmfin)

Even with all these great contributions, mangroves are disappearing at an alarming rate of approximately 1 percent per year. Over the past 50 years, half of the world’s mangroves have disappeared. The World Wildlife Fund is partnering with other nongovernmental organizations to create the Global Mangrove Alliance, a group that aims to increase mangrove coverage 20 percent by 2030.The Alliance plans to meet this goal by raising awareness, engaging with local communities, governments and private entities, and increasing investments into mangrove conservation and restoration. I was lucky enough to intern at WWF this summer working on the project.

Mangroves are unique forests that inhabit tropical estuaries and have adapted to live in salty waters, something very few plants are able to do. They are able to filter the freshwater out at the root level and some species can even secrete salt from their leaves. Some species of mangroves have spiked roots that rise above the water so that the tree can receive oxygen and many have stilted roots. Rising sea levels endanger mangroves because they will die if their roots are submerged for extensive periods.

Infrastructure projects can increase salinity and sedimentation stresses as well. For example, a dam could lower the amount of freshwater that flows into mangroves causing a salinity imbalance, increasing death rates. Construction projects may increase the amount of sediments potentially smothering the mangroves by obstructing the exchange between the roots and the soil or atmosphere. Sea level rise can cause similar effects, and while mangroves can adapt to rising sea levels by moving inland, if the sea level rises quickly enough, they will likely be overtaken.

By far, the largest threat to mangroves is from deforestation driven by aquaculture, the practice of farming seafood. It’s the fastest growing food industry and has proliferated in Southeast Asia where large swaths of mangroves are cleared to form aquaculture ponds, typically for shrimp. Ninety percent of the world’s aquaculture is in Southeast Asia, which is home to a third of the world’s mangroves. Since the world’s fisheries are severely overfished, aquaculture is expected to become the main source of global seafood by a sizable margin.

Farmers often use large amounts of antibiotics to prevent disease outbreak at their farms, which can be harmful to surrounding mangroves (and human health when seafood is consumed). Nearly half of U.S. seafood imports are shrimp, and they are largely unregulated and untested for chemicals. At WWF, we are interested in using remote sensing to account for abandoned shrimp ponds. They are abandoned because the amount of antibiotics and other chemicals used in the ponds renders them unusable, which causes farmers to move elsewhere, clearing mangroves for more ponds.

Prawn aquaculture facility (Source: Flickr/48722974@N07)

I learned that coastal resilience was one of the main priorities of the Oceans Team, one of six teams at WWF, and that mangroves are a significant part of that goal. Coastal resilience has gained international attention because of climate change threats and the international community is responding by bolstering vulnerable coastal regions.

Working at WWF has given me a behind-the-scenes look in how this important, collaborative effort is carried out. As a communications intern, I was able to sit in meetings and see how targeting videos on people’s Facebook Newsfeeds requires deliberation and forethought as well as money. Launching the Global Mangrove Alliance website requires work, money and planning and coordinating with several other organizations. We are quickly putting together to have an event on July 26, World Mangrove Day, and inviting dignitaries to help raise awareness of the Alliance.

I’m honored to help with such an ambitious and important project and am very proud of the work my team has done over the summer. The Alliance is a long term, international effort with many groups involved, and I am optimistic about their chances of achieving their goal. At the WWF, I worked alongside some of the most hardworking, brilliant and compassionate people that I’ve ever met.

Mangroves — not mangos — will likely be seen more and more as a great adaptation and mitigation measure to climate change. They are crucial ecosystems in increasing disaster mitigation and foster a lot of interesting species, including the Bengal Tiger in the Sundarbans. I’ve been to the Sundarbans and it’s truly a magical place. I will only eat sustainable shrimp and will continue to vouch for mangroves as climate change increasingly becomes a threat to coastal communities and our world.