The introduction of exotic species has a negative impact on biodiversity; they depredate native species and modify the habitat, affecting the ecosystem.
To protect the mangrove and conserve local nesting sites for birds, the Protection and Recovery of Threatened Species program developed a project to control the Possum Grape Vine* (Cissus verticillate) in Marismas Nacionales Nayarit Biosphere Reserve.
The Possum Grape Vine (Cissus verticillate), native to the tropics of Mexico, is used in natural medicine or as cattle feed. However, due to its invasive behavior in the mangrove forest region of Nayarit, it constitutes a threat for endemic flora in danger of extinction or subject to special protection, such as the Red Mangrove (Rhizophora mangle), the Black Mangrove (Avicennia germinans), the Button Mangrove (Conocarpus erectus), and the White Mangrove (Laguncularia racemosa).
The project consisted of eliminating vines in 50 hectares of mangrove forest ⎼35 hectares in the “El Rinconcito” site in Ejido Unión de Corrientes, municipality of Tuxpan, and 17.7 hectares in the “El Pochote” site in Ejido de San Miguelito, municipality of Rosamorada, Nayarit⎼ as well as cleaning and rehabilitating water flow channels and holding workshops on mangrove conservation.
This vine extends through the crown of mangroves, obstructing the entry of light and preventing the species that depend on them from developing. In times of drought, when the salinity of the water in the mangrove increases, the vine binds its roots to the trunk and obtains fresh water from there until the tree is dried. “There is serious damage because this space without mangroves leaves no place for birds to nest, there is no food for fish, there is no habitat for invertebrates,” said marine biologist Mauricio Cortes Hernandez, Regional Coordinator for Pronatura Noroeste in Nayarit and Jalisco.
It is believed the species was introduced accidentally, due to the influence of the Acaponeta, Bejuco, and San Pedro Rivers that drag the vine down river, or through mammals and birds, which feed on its fruits and transport its seeds.
Cortes Hernandez said that in order to remove this invader, work crews were formed with local fishermen who had previous experience in removal activities and who know how to work in the mangrove swamp. The team identified the most appropriate stage for elimination as the growth period before germination, as the vine’s removal is easier and the impact on the forest not yet so serious. It is important to clarify that this activity was conducted manually, without chemical methods that affect the mangrove.
In the workshops given to fishermen and ejidatarios on the importance of removing the vine, the benefits of mangrove conservation and the environmental services they provide were addressed. In addition, the protocol of action for the early detection of an invasive species was presented.
“We have been very attentive to what we can do, it is necessary that we all work and remove the vine and establish a plan for follow up and control of the species,” concluded Mauricio Cortés.
Mangroves are coastal forests. One of the most productive ecosystems on Earth, they provide fundamental environmental services for humans and protect communities against floods and hurricanes. In addition, they constitute breeding habitats for commercially fished species, provide refuge for flora and fauna, and improve water quality.
*The project was conducted in collaboration with the Commission for Natural Protected Areas, the National Commission for the Use and Knowledge of Biodiversity, the National Forestry Commission, and the United Nations Development Program.
The Pronatura Noroeste team thanks the landowners and fishermen of the Marismas Nacionales Nayarit Biosphere Reserve for their collaboration in this project, and the men and women who led the arduous removal work to protect and conserve the mangrove.
