Aztec methods and crocodiles: How biologists are restoring mangroves in Mexico.
The nonprofit REVIVE is restoring mangroves in Veracruz, Mexico, by planting seedlings on raised mounds based on an Aztec technique and by releasing Morelet's crocodiles into the Alvarado Lagoons System.
A nonprofit called REVIVE is rebuilding mangrove forest in the Alvarado Lagoons System in Veracruz, southeastern Mexico, using an Aztec-inspired planting method and reintroduced crocodiles. Studies suggest Mexico has lost more mangrove than any other country in the Americas, and many replanting projects fail because seedlings die from improper planting or unsuitable sites. According to REVIVE, its approach has produced a fully restored forest.
Biologist Aníbal Ramírez Soto, now REVIVE's director, began working in the area in 2006. Seedlings he planted in rows died. He then noticed that healthy mature mangroves grew in elevated clumps, and he built a small mound from wetland soil. He calls these mounds chinampas, after the islands the Aztecs farmed in shallow lakes. Local mangroves had been cut and burned for cattle, which made the soil collapse and sink and kept new trees from rooting. "It's a simple idea: Just put the soil back like it was," he said.
The team planted about 2,000 trees on hundreds of hand-built mounds and later counted more than 4,000, because seedlings carried in by the tides had also taken root. Trees began spreading beyond the mounds after two years, and canopy cover reached 80% by the eighth year. The work has since grown to 15,000 chinampas over 40 hectares (99 acres), with machines now building the mounds. The team posted 17 years of data in a preprint on EcoEvoRxiv.
REVIVE then added crocodiles. Ramírez Soto said they move sediment as they swim and keep channels open. The team learned the approach from Colombian biologist Giovanni Ulloa Delgado, whose group released about 15,000 juvenile American crocodiles into Cispatá Bay. Since 2017, REVIVE has released around 80 Morelet's crocodiles in Alvarado. Restoration coordinator Rafael Rodríguez Mesa said the team once cleared clogged channels by hand and later with machines, but that crocodiles can now do that work. Neither REVIVE nor the Tlacotalpan municipal office has heard complaints about the animals.
The page notes that the crocodile claims lack formal support. Ulloa Delgado has not run a formal study, and a 2020 review in Biological Reviews found too little research to prove or disprove that crocodiles act as ecosystem engineers. Charlie Manolis of the IUCN Crocodile Specialist Group, who backs crocodile conservation, said: "There's absolutely no evidence whatsoever that, for example, habitats will collapse if crocodiles are removed." He also said returning crocodiles can endanger nearby communities and called for public education. REVIVE also hopes to start a crocodile breeding program at a former shrimp farm near Tuxpan.
At a Glance
- REVIVE has released about 80 Morelet's crocodiles in Veracruz's Alvarado Lagoons System since 2017.
- A larger chinampa project covers 40 hectares (99 acres) with 15,000 mounds.
- Canopy cover reached 80% by the eighth year of the project, according to Ramírez Soto.
- A 2020 Biological Reviews paper found too little evidence to confirm or rule out crocodiles as ecosystem engineers.
Sources
This brief was written by Brightside Report from the reporting linked above. Spot an error? Request a correction.