Freshwater ecosystems at risk, as salt-loving species intrude
By Summit Voice
FRISCO — A combination of sea level rise and upstream freshwater depletion is leading to a decline of the Everglades freshwater plant communities, as salt-loving mangroves spread farther inland.
Satellite imagery over the southeastern Everglades confirms long-term trends of mangrove expansion and sawgrass habitat loss near the shore, according to a new study published in the scientific journal Wetlands.
“I was very surprised at how well the results matched our understanding of long-term trends and field data. Normally, we don’t see such clear patterns,” said lead researcher Douglas Fuller.
The findings show large patches of vegetation loss closer to the coast, approximately four kilometers from the shoreline, in and around a vegetative band of low productivity that has been shifting inland over the past 70 years. Growth trends were seen primarily in the interior, at about eight kilometers from the shore.
“Less salt-tolerant plants like the sawgrass, spike rush, and tropical hardwood hammocks are retreating. At the same time, salt-loving mangroves continue to extend inland,” said Fuller, professor of geography and regional studies in the College of Arts and Sciences at the University of Miami.
Changes in water management, such as the implementation of the Comprehensive Everglades Restoration Plan, may help offset the possible effects caused by future salt water intrusion.
“However, restoration may not suffice if sea-level rise accelerates in the coming decades,” Fuller said.
Fuller and co-author Yu Wang, a former master’s student at UM, used satellite imagery from 2001 to 2010 over the southeastern Everglades, in an area called Taylor Slough, which is the second-largest flow-way for surface water in the Everglades, and stretches about 30 kilometers along the eastern boundary of Everglades National Park.
“These methods allowed us to perform a spatially comprehensive assessment of the trends, unlike research that has been limited to plot-level studies, in which careful measurements of plant cover and composition have been made over the past dozen years,” Fuller said.
“These field studies, which provide confirmation of the satellite-based results, involved clipping and weighing plants found in sawgrass prairies and are part of a long-term effort to understand the dynamics of the ecosystems in the Everglades.”
In the future, the researchers would like to apply the methods used in their study to other coastal wetland areas that are threatened by sea-level rise.