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6 facts you need to know about mangroves

© Trond Larsen

“I love mangroves.” That’s a phrase you’ve probably never heard anyone say. Mangroves don’t inspire awe and wonder the way coral reefs, rainforests or wide-open grasslands do. In many parts of the world, they’ve long been frowned upon as dirty, mosquito-infested tangles of roots that stand in the way of an ocean view.

Even environmentalists tend to think of mangroves’ ecological role mostly in terms of protection from storms and nurseries for fish. As climate change threatens to increase the frequency and severity of storms, mangroves provide a stout defense against storm surge. Mangrove roots also provide habitats for fish and shellfish, crucial to sustainable livelihoods for coastal communities.

But that’s just the beginning — mangroves do so much more. In fact, there’s a case to be made that mangroves are the most useful ecosystem on Earth. Here are six reasons why.

1. Mangroves store more carbon than terrestrial forests.

Mangroves help people weather the impacts of climate change — but they also help mitigate its causes. Globally, protecting forests can account for as much as 30 percent of the solution to climate change thanks to their ability to absorb and store carbon dioxide. Mangroves have the capacity to take far more carbon out of the atmosphere than terrestrial forests; a patch of mangroves could absorb as much as 10 times the carbon of a similarly sized patch of terrestrial forest.

2. Mangroves may help fight coral bleaching.

One of the most pernicious effects of climate change is coral bleaching. The bleaching of Australia’s Great Barrier Reef has been making headlines this summer, but in fact this trend is occurring in all the world’s oceans, and scientists project that it will likely worsen as oceans absorb more carbon. As coral reefs are the foundation of marine life, the prospect of their death is a disaster for our oceans.While people usually classify reefs and coastal forests as distinct ecosystems, nature doesn’t recognize this boundary. In fact, young corals grow among mangrove roots, and healthy mangrove forests could provide shelter for coral species at risk of extinction from coral bleaching. Furthermore, mangroves may even play a role in reducing ocean acidification, which in turn helps prevent coral bleaching.

Dr. Emily Pidgeon, Senior Director of Strategic Marine Initiatives, spoke on the ecological importance of mangroves, their role in climate change resilience and what we can do to protect their fragile anatomies. You can listen to her podcast below.

3. Mangroves help fight climate change — but they are far from immune to its effects.

Mangroves are at home in the boundary zone that isn’t quite land and isn’t quite ocean. They require the perfect amount of sea water — too little and they dry out; too much and they drown. Sea-level rise is changing where mangroves can grow and threatening their continued existence in some of the places where they are most needed.

4. Your coconut shrimp might also be hurting mangroves.

Mangroves face dire threats with or without sea-level rise. In many parts of the world, mangroves are cut down to make room for fish ponds. Sustainable aquaculture, mostly of crabs and shellfish, is possible in mangroves, but the poured concrete structures or even mounds of dirt used for many fish ponds retain fish waste, rendering them unusable after only a few years. In the Philippines, where mangroves have a particularly important role to play in climate resiliency, fish ponds currently cover as much coastal land as mangroves.

But fish ponds are just one threat facing mangroves. People cut down mangroves for better ocean views. They are battered by wave-strewn trash. Goats eat them. Barnacles choke them. It’s hard out there for a mangrove.

5. Once mangroves are gone, they can’t simply be replanted.

Mangroves actually hold the coastline in place, giving it its shape. Once they are gone, the land erodes and tides and currents reshape the coastline, making it difficult or impossible for mangroves to grow back in their former habitats.

6. Not all mangroves are created equal.

When mangroves are planted, it is absolutely crucial to plant the right ones. Mangroves aren’t a single species — the term “mangrove” covers any of the 70 or so species of shrubs or trees that grow in saline or brackish water. Each kind of mangrove is uniquely suited to its ecological niche, and the wrong kind in the wrong place won’t survive. After Typhoon Haiyan devastated the Philippines’ coastal communities, the government committed to planting one million mangroves. Unfortunately, many were planted without regard to getting the right species in the right place, and many of the trees died.

Mangroves are a key piece of how we address climate change — helping us both adapt to its impacts and take carbon out of the atmosphere. In fact, taking all their benefits into account, there is a case to be made that mangroves do more for us than any other ecosystem on Earth.

Given their fragility, and how often we overlook them, it might be time to start working toward some serious mangrove appreciation.

Andrew Kolb was a senior director of communications at Conservation International.

 

Further Reading