Globally, few mangroves thrive in such low salinity, and only one other site has reported estuarine mangroves growing in freshwater conditions.
Due to their unique structure, these mangroves may provide unique ecosystem functions, carbon storage, and support for associated plant and animal species across their vast range.
Lower salinity may affect soil functions, including pollutant retention, carbon sequestration, and greenhouse gas emissions.
In addition, the unique soil properties of this coastal region further underpin the diversity of plant species found in this atypical mangrove environment, which has not been observed in any other part of the world.
Thiago says: “What’s really unique to me is seeing freshwater trees growing side-by-side with mangrove species, both thriving equally.:
Bernardino added: “This mysterious combination, combined with the abundance of giant Aninga herbs and Acrostichum ferns, gives the forest a unique, eerie feel that we eventually named ‘Jurassic Park Feeling’ ‘.”
Bernardino and Silva’s findings also show that the existing map mangroves in the Amazon delta expanded by nearly 20 percent, increasing their area by 180 square kilometers.
The study sheds light on the importance of field exploration of Earth’s natural habitat, as existing satellite imagery fails to detect mangroves in a significant area of the Amazon delta.
“Ecologically, mangroves provide habitat for a variety of organisms. They are our natural laboratory for understanding plants,” Silva said.
“The results from the 3-D terrestrial laser scans have allowed us to develop new ways to estimate carbon storage, from aerial root density to tree height and volume, to track the location of individual trees, and even to see underground vegetation channels. It’s fascinating.”
The second phase of the research is currently underway in Pala, Brazil, where Bernardino and National Geographic explorer Margaret Owuor will investigate and document the economic and social value that mangroves provide to Amazonian communities.
Angelo added: “We also expect that these mangroves will be key to food supply and carbon burial in this part of the Brazilian coast. There are many communities that depend entirely on local fisheries for their livelihoods and depend on fresh, clean water from the Amazon River. .
“These freshwater mangroves are in a way key to all of these services, but we need to gain a deeper understanding of these connections in these newly discovered ecosystems.”
These ecosystems are among the most productive and biologically complex on Earth.
Over the past 50 years, “aquaculture and commercial fish farming have destroyed one-third of the world’s mangroves. In some parts of the world, such as the Philippines, losses are as high as 80 percent.” According to Endangered Species International.
Nicole Alexiev, vice president of science and innovation at the National Geographic Society, concluded: “The expedition to Brazil’s mangroves, and the subsequent discovery of freshwater mangroves, was critical in painting the full picture of the vast Amazon basin.”
“Through years of inspection…we will continue to gather new information about these critical ecosystems and how we can support solutions to ensure their conservation.”
Yasmin Dahnoun is ecologist.