ENVIRONMENT

Communities in Thailand are restoring degraded mangrove forests to grow and harvest clean, healthy shrimp. (Al Jazeera)

Download and print our guide to the mangrove ecosystem, in English or Spanish—then color one yourself!

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Discussion Questions

• According to the great article from Al Jazeera, Thai aquacultural communities are planting mangrove trees along the coast. How do mangrove forests benefit shrimp farmers?
  • Shrimp “get everything they need from mangroves.”
    • Shrimp don’t get everything from the trees directly, but the submerged roots of the mangroves provide an incredibly rich and complex ecosystem.
    • Bacteria on the seafloor help decay detritus from falling leaves and branches, providing nutrients for both the soil and microorganisms on which shrimp and other primary consumers feed.
    • Shifting tides along the coast constantly filter and replenish the supply of nutrients.
    • The dappled, shifting patterns of sunlight provide protection for shrimp and other small organisms in the ecosystem. (“Small organisms” often include juveniles of larger species, such as fish. For this reason, mangroves are often regarded as nurseries for shallow marine ecosystems.)

• Shrimp farmers aren’t the only members of the community benefitting from mangrove forests. How else do mangroves benefit the community?
  • Other aquaculture crops, such as oysters, crabs, and fish, can be harvested in and around mangroves’ branching root systems. Scientists call this a “polyculture system” of agriculture.
  • Mangrove forests provide natural protection from both coastal erosion and the powerful tsunamis that sometimes impact the region.
  • Advocates of reforestation say, “We often refer to mangroves as the supermarket for the local people because, there, they have some building supplies, food supplies, shelter and medicines. So people have been traditionally relying on the mangroves for all those things in the local fishing communities.”

• If mangrove forests are so beneficial to coastal Thai communities, why have so many forests disappeared?
  • Since the 1970s, the Thai government has encouraged expansion of the aquaculture industry to boost economic development. The program has largely worked, too: Today, Thailand is the third-largest exporter of seafood (only trailing powerhouses China and Norway).
  • Intensive shrimp farming relies on large, artificial, freshwater ponds. Some of these ponds are inland, and some are on the coast, where mangroves have been razed to make way for them. These farms “use antibiotics, fertilizers, disinfectants and pesticides that, in Thailand, are often released into the natural streams of water without being treated beforehand.” This runoff impacts the soil and water quality that allows young mangrove trees to grow.

• The organic shrimp industry supported by Thailand’s mangrove forests is healthier for the environment and more economically stable for farmers. Why aren’t all Thai or other Southeast Asian fish farmers embracing reforestation?
  • Organic shrimp are more expensive, what Al Jazeera calls a low “cost efficiency.” “Consumers want [shrimp] cheap, and this is part of the problem,” says one expert.
    • “Thailand has been trying to find technological fixes to keep the production going. First, they moved the production inland into freshwater, and later, they introduced new species like the white shrimp.”
      • White shrimp, introduced because they were initially more disease-resistant than indigenous species, decimated the Thai shrimping industry when a single epidemic killed thousands of shrimp on hundreds of farms.

• Have intensive agriculture practices radically altered other coastal or inland ecosystems around the world?
  • Uh, yeah, everywhere but Antarctica. Notable examples:
    • Farming and ranching have destroyed thousands of acres of the Amazon rain forest ecosystem in northern South America.
    • Farming and ranching nearly eliminated the entire tallgrass prairie ecosystem of the midwestern United States.
    • Dams in the United States prevented the natural flow of water to the Colorado River delta in Mexico, nearly destroying a delicate wetland ecosystem.
    • Intense irrigation has resulted in increased soil salinity in Australia’s most arid farming areas. Soil salinity reduces both crop yields and the number of native plants able to tolerate the salty soil.
    • Perhaps the most dramatic example of agricultural decisions impacting a natural ecosystem is the disappearing Aral Sea, where rivers were diverted for irrigation.

TEACHERS TOOLKIT

Al Jazeera: Thailand: Reclaiming mangroves for shrimp production

Nat Geo: Mangrove Ecosystem diagram (English)

Nat Geo: Mangrove Ecosystem diagram (Spanish)

Nat Geo: Mangrove Ecosystem diagram (coloring page)