Why mangroves matter: Experts reply on International Mangrove Day

Mangroves protect coastlines, filter out pollutants, and are home to a wide array of life, but have declined sharply around the world. What does the disappearance of this special forest ecosystem mean for our planet? Experts respond.

The tsunami that struck Southeast and South Asia in late 2004 killed nearly 230,000 people and destroyed villages, towns and cities across 14 countries. But some affected areas escaped the massive devastation that other regions saw — thanks to healthy mangroves dotting their coastline and acting as protective barriers.

Sitting at the edge of land and sea, mangroves are unique in many ways. The mangrove trees and shrubs form dense forests, their special, intertwining roots helping them survive in the saline and brackish waters they call home.

These forests are skilled at filtering pollutants from river water. They are adept at trapping excess sediment before it reaches the ocean. They are also carbon powerhouses, a tract of mangrove locking away many times more carbon in the soil than a similarly sized area of rainforest.

Moreover, mangrove swamps are important nurseries for several fish species, and support a massive diversity of wildlife, including tigers, crocodiles, otters, turtles and several species of birds and insects.

Given all that mangroves do, it is unsurprising that the forests have a special day dedicated to them: July 26, International Mangrove Day.

However, mangroves have declined rapidly around the world, losing out to shrimp farms, tourist resorts, agricultural and urban land over the past decades.

What does the disappearance of this special forest ecosystem mean for our planet? This is what some mangrove experts have to say.

Catherine E. Lovelock, professor of biological sciences at the University of Queensland, Australia

Without mangroves, we would all be diminished and many people would suffer. It’s a dismal scenario that includes coasts with barren, unproductive shores, collapsed fisheries, turbid, polluted water, little protection for communities from severe weather events and sea level rise and loss of many types of animals and plants.

It would be a world without mangrove tigers, mangrove honeyeaters, mud crabs or mangrove mud whelks.

While these losses are felt most intensely by communities that have removed or degraded their mangroves, they ultimately affect all of us through reduced food security, enhanced migration, and increased potential for conflict.

If we all attend to the conservation and restoration of mangroves not only will local communities benefit, but the global community will benefit by increasing the carbon sink of the coastal zone, helping to limit global warming.

Catherine E. Lovelock, professor of biological sciences at the University of Queensland, Australia

 

Losses of mangroves also release large amounts of carbon dioxide into the atmosphere, arising from the destruction of their biomass and the release of the large carbon stocks held in their soils. This affects all of us on the planet as it contributes to global warming, further accelerating global climatic change.

Protection and restoration of the mangroves that we have already lost or degraded should have the highest priority because of the benefits to people, biodiversity and the planet.

In my country, Australia, restoring the mangroves and other coastal wetlands will benefit the iconic Great Barrier Reef, improving water quality and fisheries.

In other countries where I work, for example, Myanmar, conserving and restoring mangroves is critical for the health of the communities of the Irrawaddy Delta who rely on the mangrove for their livelihoods and security.

If we all attend to the conservation and restoration of mangroves not only will local communities benefit, but the global community will benefit by increasing the carbon sink of the coastal zone, helping to limit global warming.

Beth Polidoro, associate professor at Arizona State University and co-chair of marine fishes, Red List Authority, IUCN

Mangroves are important habitat-forming species at the interface of freshwater, marine and terrestrial ecosystems.

As such, they provide a number of critical ecosystem services including protection from coastal erosion and storm damage, natural filters for pollution and sediment, carbon sequestration, and critical habitat for a wide variety of species, including nursing grounds for many coastal fishes.

It is estimated that 80 per cent of global fish catches are directly or indirectly dependent on mangroves.

A world without mangroves would likely mean a world with fewer fishes, more coastal damage, and unknown ecosystem and public health consequences related to changes in pollutant, sediment and carbon cycles.

Norman Duke, professorial research fellow, mangrove hub, James Cook University, Australia

Love them or hate them, we all depend on mangroves and tidal wetlands. They have been the quiet achievers that have somehow adapted to fit among our everyday lives.

Facing the sea and bordering river and stream estuaries, these habitats offer essential services that will be sorely missed when they are further diminished. But our communities are driven by short-term gain in alternate land uses, and detrimental pollution.

There appears to be little regard for the advantages provided by natural ecosystems because they have rarely been valued in our terms. After all, their services have been provided for free. Why should we now pay for these benefits? And this is the nut of the current dilemma.

There are many major environmental benefits that usually go under the fiscal radar. That means we are grossly undervaluing such natural places.

Norman Duke, professorial research fellow, mangrove hub, James Cook University, Australia

Tidal wetlands are highly threatened by both an expanding global footprint of human development, coupled with rapid alterations to the world’s climate. The world we live in is fast changing and the natural environments must adapt and adjust to survive!

The challenge is to convince people that mangroves are useful, and healthy natural environments are good for them!

One seemingly rational approach has been to give a fiscal value to natural places. But that is not easy. While we can relatively easily place a dollar value on the support and harbouring of local and nearshore commercial fisheries by mangroves, what about recreational values?

There are many major environmental benefits that usually go under the fiscal radar. That means we are grossly undervaluing such natural places.

For mangroves, these benefits include shoreline protection and mitigation of waterways troubled by severe flooding and violent storms, plus their acknowledged extreme capacity to sequester carbon from the atmosphere — five greater than other forested places. And each of these things is increasingly threatened already as the climate changes.

And, of course, perhaps the greatest threat of all is rapidly rising sea levels. The effects on shoreline and estuarine places will be, and already is, extreme and devastating for natural environments as well as human society. How do we put a value on shoreline places?

At the end of the day, we know it will be immense — so does it really matter how much it is? The only way forward, it seems, is to better inform and educate human communities. This is our greatest and most urgent challenge!

While the public perception of tidal habitats remains divided, these valuable places are rapidly being removed and damaged beyond recognition, and diminished benefits. The question is, can these habitats cope?! And is there enough time for them to adapt?

Our best available evidence suggests they are not coping well! The squeeze is real, with accumulative pressures of ever-increasing human populations, resource demands and development combined with the progressive impacts of changing climate and rising sea levels. These are impacts never known on Earth before. There seems little reason for optimism!

So my message is all about promoting better awareness and education. People don’t have to love mangroves to appreciate their value. Mangrove natural habitats really need our greater understanding and help at this time.

Majestic mangroves — healthy humans!

Eco-Business published this story with permission from Mongabay.

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