Scientists have developed a predictive model using satellite observations to identify early signs of coastal marsh decline. This groundbreaking research offers an invaluable early warning system to help preserve these vital ecosystems.
Researchers from Colorado State University, the University of Georgia and the University of Texas at Austin have identified early warning signs of coastal marsh deterioration, presenting an unprecedented opportunity to protect these vital ecosystems before visible damage occurs.
The study, published in the Proceedings of the National Academy of Sciences, showcases a model that uses satellite observations to detect declining root production, an early indicator of marsh failure.
This model offers an early alarm for ecosystems that serve as frontline defenses against coastal flooding.
“Our findings show widespread belowground decline over the past decade and suggest this is an early warning sign of marsh deterioration and loss,” lead author Kyle Runion, a research scientist at the University of Georgia who conducted the study while he was at UT Austin’s Marine Science Institute, said in a news release. “By pinpointing where belowground loss is happening, we can get a head start on conservation and restoration projects to more effectively prevent marsh loss.”
Coastal marshes perform critical functions such as filtering water, storing carbon, providing habitat for wildlife, and offering food and livelihoods through fishing. Notably, they absorb storm surges and mitigate sea-level rise, thereby preventing inland flooding.
“These marsh areas might be in someone’s backyard,” added senior author Jessica O’Connell, a CSU professor and Runion’s adviser. “It’s important to have this early warning and a chance to do something before you lose these special landscapes that people have an economic or emotional connection to.”
The researchers focused on the marsh grass Spartina alterniflora, prevalent along much of the U.S. coast. Analyzing an extensive field dataset from Georgia’s coastline, they found that belowground biomass has declined across 72% of Georgia’s coastal marsh since 2014, with nearly 30% experiencing substantial loss.
The team aims to adapt the model for universal application to all marsh plants and coastlines.
Caption: Declines in belowground biomass can indicate marsh vulnerability to loss. This diagram illustrates how a healthy salt marsh (left) can convert first to a vulnerable marsh (middle) before loss of the vegetated marsh (right) as a result of increased inundation intensity, which is driven by sea-level rise.
Credit: Kyle Runion/Colorado State University
The team’s Belowground Ecosystem Resiliency Model (BERM) leverages over a decade of field data from the Georgia Coastal Ecosystems Long Term Ecological Research Program.
The program, funded by the National Science Foundation and led by co-author Merryl Alber, a UGA professor and director of UGA’s Marine Institute, collected aboveground and belowground marsh grass data.
“Coastal wetlands such as salt marshes historically have responded dynamically to keep pace with sea-level rise in part by developing extensive root networks, which expand the soils with organic-rich material,” Runion added. “This accumulation of ‘blue carbon’ drives elevation gain and enables the marsh surface to maintain elevation relative to rising sea levels.”
However, sustained high water levels can deoxygenate root systems and lead to vegetation decline.
“The declines in vegetation were closely related to flooding pressure, which will only worsen with the rapid acceleration of sea-level rise that the southeast U.S. is experiencing,” added Alber. “That is why this work is so important.”
By predicting both above- and belowground biomass, BERM not only highlights areas of concern but also provides a framework for targeted conservation initiatives.
The team applied the model to all Georgia locations of Spartina alterniflora, mapped by co-author Christine Hladik, a geography professor at Georgia Southern University.
The early identification of declining coastal marshes offers a precious window for intervention, potentially preserving these ecosystems that are so crucial to environmental stability and human livelihood.
Source: Colorado State University