1. Inhalt
  2. Navigation
  3. Weitere Inhalte
  4. Metanavigation
  5. Suche
  6. Choose from 30 Languages

Global Ideas

Bringing devastated mangroves back to life

For decades, shrimp aquaculture has been laying waste to mangroves. But a unique approach to their restoration offers hope for reclaiming some of the world's most precious ecosystems.

Green Nypa palms on a coastline (Source: Qaalvin / CC BY-SA 3.0 https://commons.wikimedia.org/wiki/File:Nipa_palms.jpg)

Nypa palms are part of mangrove forests; they thrive on soft mud

Florida-based wetland scientist Roy Lewis has been trying to coax mangroves back to life for decades. Back in the early 90s, the situation was so dire that the chances of restoring coastlines devastated by shrimp aquaculture seemed slim. But ensuing years have seen an explosion of replanting projects - often funded by the shrimp industry itself. Many, however, promise more than they deliver.

"I did the same kind of experiments a lot of people have done," says Lewis, who developed the #link:http://www.mangroverestoration.com/index.html:Ecological Mangrove Restoration# (EMR) method now being used across Southeast Asia. "I began over 40 years ago: sticking mangrove seeds in the ground and watching them die. It was obvious there had to be a better approach."

"Mangrove" is a blanket term for trees and bushes from around 15 distinct plant families indigenous to tropical regions across the globe. Their common characteristic is that they have adapted to thrive, semi-submerged, in tidal saltwater - where they provide a unique and nurturing habitat for growing fish, marine invertebrates and roosting birds.

Two men planting mangroves (Source: MangroveActionProject / CC BY-NC-SA 2.0 https://www.flickr.com/photos/seminarsonscience/3639568430/in/photolist-4A5w1c-4A5tMg-4A5spc-4A5sFv-4A5tfv-4A5pzv-4A9KsG-4A9GZ3-4A5rEk-4A5rK6-4A9JaA-4A5rAi-4A9HVu-4A5wiF-4A5u1X-4A5ws8-4A5sKB-4A5vtH-4A9HFs-4A5sdV-4A9J2E-4A9JZG-4A5tHZ-4A5tAR-4A9HRf-4A5pRK-4A5wdB-4A9EDN-4A9HDh-4A9La3-4A5rSc-4A5r9M-4A9G7s-4A9Fy7-4A9FTf-4A5qYB-4A5qUt-4A5qBa-4A9G3Y-4A9FKA-4A9FPf-4A9KQj-qRiyUC-hBiRVd-6xxAo6-6xxAhH-3TzwP1-6xBJTQ-6xBK1j-6xBK9s)

Mangroves produce millions of seedlings each year if conditions are right

In recent years, there has been an increased awareness of the important roles mangroves play - not only in protecting shorelines from erosion, but also for sequestering carbon.

'Rape and run'

Yet awareness does not necessarily imply a willingness to act in a preventative fashion. Alfredo Quarto of the Mangrove Action Project estimates that around half the world's mangroves have already been lost, and that some 150,000 hectares are still being destroyed each year.

The biggest culprit is shrimp aquaculture. Fueled by consumer demand - primarily in Europe, the United States and Japan - the industry has laid waste to coastal ecosystems across South and Southeast Asia, as well as Central America.

"Shrimp farms often only operate for about two years before being closed down because of disease or pollution problems," Quarto told Global Ideas. This is what he describes as a "rape and run" type of investment. "Either they go bankrupt, or they have enough money to move to a new place - devastating each area and leaving a wasteland behind them."

Restoring nature's hydrology

Despite closer monitoring of the industry, which the #link:http://ejfoundation.org/sites/default/files/public/shrimp_report_v44_lower_resolution.pdf:Environmental Justice Foundation# highlights as fertile ground for human rights abuses, Lewis estimates around half a million hectares of former shrimp aquaculture sites now lie abandoned.

Photo: A loamy coastal area without vegetation (Source: Joanna Gottschalk / DW)

Shrimp farms are arising due to high demand for the crustaceans and are the main reason for mangrove destruction

Against that ravished backdrop, conservationists face a major challenge. But as Lewis, who is also technical advisor for the Mangrove Action Project explains, the EMR method fosters regeneration by creating the perfect growth environment.

"You have to carefully look at topography, the amount of water flowing and the tidal exchange," Lewis explained. "Planting is often not necessary. Mangroves produce millions of seeds every year. If you do your homework and do the right restoration, the seeds will float in on their own."

Luxury exports at the expense of food security

Given that mangroves perform a host of environmental services that also benefit local communities, losing those ecosystems has a domino effect. One of the biggest threats posed by their loss to aquaculture is food security.

Beside the negative impact on fish stocks, aquaculture contaminates aquifers with salt water, which means local communities lose their pastures and are unable to raise livestock. In some cases, Quarto said, fresh water has to be brought in on trucks.

"We have more food security in the US and Europe and Japan than they have in Thailand, India, Bangladesh and so on - and yet they are exporting around 95 percent of the shrimp produced in these countries," Quarto said. "Shrimp farm areas, by and large, are causing food insecurity as they produce food for export for richer nations that don’t need it."

Mangrove destruction also has social and cultural implications, with old fishing and agricultural traditions getting lost. Conservationists at the #link:http://mangroveactionproject.org/:Mangrove Action Project# (MAP) believe working with those who depend on the mangroves is vital to their restoration.

Eroded soil (Source: MangroveActionProject / CC BY-NC-SA 2.0 https://www.flickr.com/photos/mangrove_action/2354690931/)

The destruction of mangroves also has a stark impact on fishing and agriculture

Working with the community

Jim Enright, who heads MAP's Asia office, says one of the reasons so many mangrove restoration projects have failed is that affected communities are not invited to take part in the process. "If they do involve local people, they are just called on to help plant, but are not involved in the planning."

In Thailand, where Enright is based, MAP is involved in several restoration projects that train local people in EMR methodology and pay them a minimum wage to work on restoring a given area's hydrology. Communities also play a role in data collection, monitoring, planning and assessment.

One recent idea from a newer project was a study trip to see more established sites.

"Communities talking to communities can really disseminate information very effectively," Enright said.

WWW links