UNAM study damages due to loss of mangrove in Mazatlan’s El Infiernillo estuary

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UNAM researchers analyzed the loss of mangroves, their ability to retain blue carbon and the impact that their eventual destruction could have on the atmosphere. In the last century, this coastal system lost 68% of its vegetation cover.

Mazatlan, Sinaloa.- If the mangrove that still remains in the El Infiernillo estuary were removed, large amounts of carbon dioxide would be released into the atmosphere, contributing to global warming. These greenhouse gases would be equivalent to the emissions generated by all the vehicles in Mazatlan for a month, according to a study carried out by researchers from the National Autonomous University of Mexico (UNAM).

This is possible because mangroves capture and store carbon dioxide (CO2) in the form of organic carbon in their branches, leaves, and roots, as well as in the sediments that bury the organic matter that results from the decomposition of the litter. But with the destruction of the mangrove and the disturbance of the land, the organic carbon that remained sequestered in the sediments is transformed back into CO2 and released into the atmosphere.

Johanna Jupin, a doctoral student at the Institute of Marine Sciences and Limnology of the UNAM, Mazatlán Unit, carried out a study to estimate the storage of organic carbon in the mangrove sediments that still remain in El Infiernillo.


Estero Infiernillo Mazatlan
The estuary lost more than two thirds of its mangroves in the last century. This is all that’s left. Photo: Christian Lizárraga/Son Playas.

Measurements carried out between January and July 2019 indicate that the carbon accumulation capacity in the estuary was reduced by 49 percent during the last century due to the alterations generated by urban expansion and the discharge of pollutants.

Still, the existing mangrove could release up to 2,507 tons of carbon into the atmosphere if it were removed or disturbed, Jupin reported. These emissions would be equivalent to those produced by recharging the cell phones of all the inhabitants of Mazatlan for 42 years, assuming that the 502,547 inhabitants have a cell phone and recharge it once a day.

The carbon inventories buried in the sediments that were analyzed are also similar to the emissions generated by the 160,000 cars that circulate in the municipality for a month.

These comparisons give us an idea of ​​the importance of mangroves in mitigating climate change, said Dr. Ana Carolina Ruiz Fernández, a researcher at UNAM and advisor to the study.

Johana Jupin, Carolina Ruiz and postgraduate students during sediment sampling.
Photo: courtesy.

Because it is important?

By increasing its concentration, carbon dioxide causes the atmosphere to retain more heat than necessary and consequently, temperatures rise.

Mangroves, like seagrasses and salt marshes, capture carbon dioxide from the atmosphere and store it as organic carbon, also known as blue carbon. Furthermore, mangroves can capture and store up to five times more carbon dioxide than terrestrial trees.

Therefore, one way to regulate the climate is the restoration and conservation of this type of coastal ecosystem, explained Ruiz Fernández, who is a specialist in sediment geochemistry and geochronology, focused on the study of the impacts of global change on aquatic systems.

Losses of Estero El Infiernillo

It is estimated that more than a quarter of the global mangrove cover has been lost in the last 50 years and that the mangroves that remain are being destroyed at a rate three to five times faster than terrestrial forests, according to the report. published by the United Nations Environment Program (UNEP) in September 2014.

Land-use change and pollution are some of the most important causes of its degradation. El Infiernillo is a clear example of what is happening in other parts of the country and the planet.

Estero El Infiernillo, Mazatlan
The mouth of the estuary was reduced from 500 meters to 40 meters between 1933 and 2020.
Photo: Christian Lizárraga/Son Playas.

Ruiz Fernández pointed out that there are records that over the last century the extension of the mangrove swamp in the estuary was reduced from 300 to 96 hectares, which represents 68 percent of the total, while the water coverage was reduced by 75 percent.

In turn, the length of the mouth of the estuary decreased by 92 percent from 500 meters to only 40 meters wide, according to the comparison recently made by Johanna Jupin between aerial images taken in 1933 and satellite images from 2020. This drastic reduction can be seen at the height of the Juárez bridge that is located on Gabriel Leyva avenue.

We all lost

The progressive disappearance of the mangrove and the El Infiernillo estuary translates into an economic and social cost due to the damage caused by the release of additional carbon dioxide into the atmosphere, which in this case exceeds 635 thousand dollars per ton of CO2 released, the researchers noted.

Apart from this, we should add the loss of biodiversity, such as birds, fish and crustaceans, as well as the protection they offer in case of storms and the containment of floods when the tide rises. 

The gradual disappearance of the mangrove swamp in Mazatlan has also been documented through cartographic studies of the Mangrove Monitoring System of Mexico, which includes measurements of the Urías estuary and the Presidio river, in addition to the Huizache Caimanero lagoon system that encompasses the municipalities of Mazatlán and Rosario. , all of them, affected by human activity.

BLUE CARBON FACTS

  • Blue carbon is the organic carbon that is captured and stored by coastal ecosystems of mangroves, seagrasses and salt marshes.
  •  Mangroves are capable of storing up to 1,000 tons of carbon per hectare.
  • They store three to five times more carbon than terrestrial forests.

Source: Semarnat, sonplayas.com