Above: Aerial view of mangroves along the San Pedro Martí l River in Mexico.
A group of researchers from the University of California focused on an ancient and unusual mangrove forest in Mexico's Yucatan Peninsula, which they said was "trapped in time".
In a study published in the Proceedings of the National Academy of Sciences on Monday, researchers observed how this special mangrove forest survives and thrives about 200 kilometers from the coastline, although mangroves usually only grow in salt water.
Growing in mysterious mangroves far from the coast
Above: Aquatic organisms in the San Pedro Martí l River in Tabasco, Mexico, have found refuge in the underwater roots of mangroves.
When a scientist who grew up in this area told the research team the strange location of this forest, these researchers first discovered the existence of this forest. Carlos Brelaud is a botanist at the Autonomous University of Tabasco Juá rez. He has done a lot of work in his hometown and classified ecosystems and biodiversity.
Earlier, he and an alumnus of the University of California filmed a short film about mangroves to remind scientists of the existence of this forest. In the movie, Brelo recalled his first visit to the San Pedro Martil River 35 years ago and marveled that the trees there were different from any he had ever seen.
Brelo said, "When I was a child, I often fished here and played in these mangroves, but we never knew how they got there. This is also a key issue that brings the research team together. "
This forest is a relic of the inland sea.
Above: A mangrove forest grows in the calm and calcareous fresh water of the San Pedro Martel River in Tabasco, Mexico.
In their analysis, the researchers want to find out how these mangroves thrive in the fresh water along the San Pedro Martí l River in Tabasco, Mexico. Mangroves, or American mangroves, usually grow only in salt water on tropical coasts. This forest is too far away from the coast, and these trees can't touch the seawater at all.
Using genetic, geological and vegetation data and historical sea level model, scientists determined that this mangrove actually began to grow in this area about 654.38+25 million years ago, when the ocean obviously extended inland. This period is called the penultimate interglacial period, and it is a short warm period between glacial periods. Although the sea water has receded with the change of the world, it is incredible that mangroves still exist.
An ancient ecosystem.
Above: Aerial view of mangroves along the San Pedro Martí l River in Mexico.
One way for the research team to determine the age of these trees is through gene sequencing. They compared the mangroves in the San Pedro Martil River with 79 trees at 1 1 along the peninsula. Their findings suggest that this group may have migrated from the area near the modern coast, when the area was still full of salt water. Mangroves are not the only trees left over from the past: the genomes of nearly 100 other trees also show signs of this origin story.
Felipe Zapata, a biodiversity researcher at the University of California, Los Angeles, who led gene sequencing, said: "This discovery is extraordinary. The mangroves here not only show their origins in their DNA, but also the entire coastal lagoon ecosystem in the last interglacial period found shelter here. "
This is a forest "trapped in time"
Above: Aquatic organisms in the San Pedro Martí l River in Tabasco, Mexico, have found refuge in the underwater roots of mangroves.
When the forest first began to grow, Yucatan Peninsula looked very different. At that time, the sea level was about 20 to 30 feet (6 to 9 meters) higher than it is now, which flooded most of Tabasco's lowlands.
Octavio Abto-Oropeza, a marine ecologist at the Scripps Institution of Oceanography at the University of California, San Diego, who participated in the study, said, "The most surprising part of this study is that we can study a mangrove ecosystem that has been trapped for more than 654.38 million years. There must be more to be discovered about how many species in this ecosystem have adapted to different environmental conditions in the past 654.38 million years. Studying these past adaptations is very important for us to better understand the future situation under climate change. "
Need more research and protection.
Above: Looking down from the air at the San Pedro Mártir River in Tabasco, Mexico, it highlights the unique natural tuff dam structure of this river.
Researchers say more needs to be learned about how this forest has survived for thousands of years far from the ocean.
Some key evidence may disappear or even be completely lost. Humans have left too many traces in this forest, and may have influenced other species, which could have been evaluated beneficially. In 1970s, in order to make room for animal husbandry, the plains around the river were largely destroyed. This mangrove forest survived only because the ground was too wet.
The researchers wrote in the paper: "We hope that our research results will convince the government of Tabasco and the Mexican Environmental Management Agency of the necessity of protecting this ecosystem. The story of the Pleistocene glacial cycle is written in the DNA of plants, waiting for scientists to decipher it, but more importantly, the San Pedro mangrove forest warns us that if we do not take urgent action to stop greenhouse gas emissions, climate change may have a huge impact on the coastal plains of the Gulf of Mexico. "
Mangrove reserve
Above: Tall mangroves provide habitats for various epiphytic cacti and orchids, creating a unique ecosystem in the world.
Mangroves are also one of the best carbon sinks on earth. It is perfectly reasonable to protect them only for climate purposes. On the coast, they also provide important habitats for rare creatures and protect them from storm surges.
However, these omnipotent trees are threatened by sea level rise, and by the middle of this century, sea level rise may devour a large number of mangroves around the world. For climate, biodiversity and the 5.3 million people they protect, their disappearance will be a great loss.
Many disciplines have revealed this forest through trees.
Above: Researchers from the University of California, Riverside and the Climate Science Alliance are exploring the exposed quarries around the San Pedro Martí l River in Tabasco, Mexico, to better understand the geological history of the region.
Finally, the researchers believe that the strength of their interdisciplinary team has solved the mystery of this inland mangrove forest.
Paula Ezcurra, science project manager of the Climate Science Alliance, said: "It is not enough to rely on each part, but when genetics, geology, botany and field observation are combined, an incredible story will be told." She made a sea level model for this project. "Every researcher has contributed his professional knowledge, which finally helped us uncover the mystery of mangroves more than 654.38 million years ago."
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