A mangrove forest located in the center of the Yucatán Peninsula defies scientific consensus by growing far from the beaches and coastal regions. The presence of such a dense forest in the San Pedro Martin River region led researchers from the University of California conduct a study to find out how this was possible.

Basically, mangrove forests tend to grow near beaches and other coastal areas as their vegetation is highly tolerant. to salt water of the seas. This is because this vegetation has properties that filter up to 90% of the aquatic salinity, feeding on the fresh water that is left over from this process.

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Image shows a mangrove forest that grows far from the beaches, the subject of scientific study by the University of California
Mangrove forest is a remnant of a distant past, when the sea level was much higher and the Tabasco region was completely inundated by the ocean (Image: Octavio Aburto/University of California/Reproduction)

The study, published on the 4th in the journal Proceedings of the National Academy of Sciences, reveals that the existence of the forest is not really a scientific anomaly, at least not in the botanical sense. Like other mangroves, this region actually grew in the middle of the seas – about 125 years ago.

Through temporal modeling techniques and integration with geological, genetic and vegetation data, the scientists were able to determine that the San Pedro Martin river mangrove forest comes from a time. where the sea level was considerably higher, but approximately 125 years ago, the oceans receded to where they are today, leaving the forest isolated.

The discovery serves as a kind of “photograph of time”, giving researchers a good idea of ​​what the Earth ecosystem at a time when its temperature was warmer and the ice caps were practically melted, raising sea level.

“The best part of this study is the fact that we were able to examine a mangrove system that has been isolated for over 100 years,” said Octavio Aburto-Oropeza, co-author of the paper and marine ecologist at the Cripps Institute of Oceanography, attached to the University of California-San Diego. “Certainly, there is much more to discover about how these many species have adapted over different environmental conditions over 100 years. Studying these adaptations will be very important for us to understand future conditions caused by global warming".

According to the study, at the time of the emergence of the mangrove, the sea level was between six and nine meters higher - a volume more than enough to completely flood what today corresponds to the region of Tabasco, one of the 31 Mexican states, located in the southeast region of the country. This proves that much of the Gulf of Mexico plains terrain was underwater during the last interglacial period (name given to moments in time positioned between ice ages: the current Holocene period we live in, for example, is considered an interglacial period ).

The idea of ​​researching this ecosystem came from Carlos Burello, a botanist specializing in mangroves and a native of Tabasco. He says that, as a child, he used to play in the mangrove swamp, but he never really understood how this forest “got there”. As an adult, his analytical work in the region served as the basis for the award-winning documentary “Memories of the Future: the modern discovery of a relict ecosystem” (“Memories of the Future: The Modern Discovery of an Ecosystem Relic”),

This documentary, in turn, provided the basis for the paper of the Californian university.

Aerial photo of the San Pedro Martin region, a river in the state of Tabasco, Mexico
Region is located in Tabasco, a state of Mexico that has the San Pedro Martin River, but no sea (Image: Octavio Aburto/University of California/Reproduction)

Claudia Henriquez and Felipe Zapata led the genetic analysis of the region, not only noting the approximate age of the mangrove and the reason for its existence away from the beaches, but also identifying other vegetation species that also live in the area, but whose biology, in normal situations, would place them closer to the coast.

“This is an extraordinary discovery,” said Zapata. "Not only because this mangrove with its origins imprinted in its DNA, but also because the entire coastal ecosystem of the last interglacial period found refuge here."

The study's authors and collaborators, however, highlight a problem: the region was systematically devastated as a result of a poorly conceived urban development plan, and the human presence is still a threat to what little ecosystem remains. Therefore, there is a need to raise awareness among local authorities about the preservation of the mangrove, and its historical importance for scientific study.

“We hope our results will convince the Tabasco government and Mexico's environmental administration to defend this ecosystem,” said Paula Ezcurra, Science Program Manager at the Climatic Scientific Alliance, who participated in the study.

“The history of glacial cycles from the Pleistocene period is written in the DNA of your plants, waiting for scientists to decipher it, but more importantly, the San Pedro mangroves are warning us of the dramatic impact of global warming on the coastal plains of the Gulf of Mexico, if we do not take urgent action to stop the emission of greenhouse gases”, he commented.

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