How valuable are Mexico’s mangrove swamps?

Mangrove swamps have an undeserved reputation for being impenetrable thickets harboring noxious insects and reptiles. But they also have considerable value, in terms of both ecology and economics, as this case study of the Marismas Nacionales mangroves on the west coast of Mexico will demonstrate.

The Teacapán-Agua Brava-Marismas Nacionales Lagoon System extends northwards along Mexico’s Pacific Coast from San Blas in Nayarit to the southern part of Sinaloa. It is one of Mexico’s largest areas of mangroves. The total area of mangroves in the Marismas Nacionales is estimated at 58,100 hectares (224.3 square miles). Four species of mangroves are found here:

• black mangrove (Avicennia germinans)
• white mangrove (Laguncularia racemosa)
• red mangrove (Rhizophora mangle)
• button mangrove (Conocarpus erectus)

Mangroves in Mexico are estimated to be disappearing at a rate of at least 2% per year, though the available evidence suggests that the Marismas Nacionales mangroves are relatively undisturbed.

A 2012 study, undertaken by a group of Stanford Students for the Ocean Innovations Environmental Defense Fund considered the ecosystem services provided by Mexico’s largest area of mangroves, the Teacapán-Agua Brava-Marismas Nacionales Lagoon System of Nayarit and southern Sinaloa and attempted to calculate the mangroves’ carbon sequestration potential.

The ecosystem services considered included:

• fisheries for shrimp, mollusk, fish and crustaceans.,
• aquaculture (primarily shrimp), forestry (charcoal, firewood, wood and roofing materials),
• agriculture,
• coastal protection (mangrove roots help bind unstable coasts, preventing erosion and providing a natural barrier against hurricanes),
• habitat for other species (breeding, shelter and feeding places for fish, crustaceans and birds) and
• ecotourism (as in Mexcaltitán)

The report tries to quantify the value of each of these services. For example, it finds that the total annual revenue brought in by coastal fisheries alone around Marismas Nacionales (including shrimp, catfish, crabs and sharks) almost certainly exceeds $10.8 million.

In terms of carbon storage, the study took into account the carbon sequestered in the form of biomass (as a result of photosynthesis) as well as the carbon exported from the ecosystem via processes such as respiration, sediment burial and mineralization. The total Net Ecosystem Production (NEP) of carbon in the Marismas Nacionales was calculated to be 8 metric tons of carbon/ha/yr or about 470,000 metric tons/yr for the entire area.

Reference:

• Marismas Nacionales Conservation & Carbon Sequestration Study. Preliminary Report (pdf file)

Related posts:

• Where are Mexico’s mangrove swamps?
• How ecological is ecotourism in Mexico?
• How sustainable is commercial fishing in northwest Mexico?