A saltwater poison is threatening prairies of toothy sawgrass on the edges of the Everglades as sea levels rise with a warming planet.
The iconic fauna of Florida’s river of grass once thrived in a nourishing overflow from Lake Okeechobee, and is included in restoration efforts to undo some of man’s meddling in the state’s natural plumbing system.
But the multi-billion dollar plan didn’t consider the impacts of sea level rise, a problem revealed in a new study by Florida International University scientists who say rising oceans are outpacing restoration.
“I’ve been using the phrase that we need to fight water with water, and that’s what we try and argue, that we need more freshwater to combat the saltwater,” said Rene Price, chairwoman of FIU’s Department of Earth and Environment and a co-author of the study. “Everyone knows sea levels are rising, but we wanted to see how water managers were combating it.”
In 2000, Congress approved the Comprehensive Everglades Restoration Plan, or CERP. The approximately $13 billion project is trying to find the “right quantity, quality, timing and distribution” of freshwater that will most closely mimic Mother Nature.
According to the South Florida Natural Resources Center, more than 650 billion gallons of water per year once flowed south into Everglades National Park across what is now Tamiami Trail. The 100-mile road from Miami to the Gulf of Mexico is a barrier for water reaching the park and eventually Florida Bay.
Currently, center Director Robert Johnson said about 280 billion gallons per year are making it into the park while sea levels are on the rise.
Between 2001 and 2015, about 5 inches of sea level rise was measured in the southern Everglades, Price said. The global average of sea level rise is about 3 millimeters per year. The average in South Florida is 7 millimeters.
“Nobody really understands why the rate of sea level rise is faster in Florida,” Price said.
But its impact on sawgrass creates a domino effect in the Everglades eco-system. Sawgrass grows in rich, dark peat — the organic remains of dead plants. When sawgrass dies, the peat expands and decomposes quickly, creating a drop in ground level, which makes it even more susceptible to seawater inundation.
“There are areas that were once sawgrass prairie that now look like open bay,” Price said. “There is still life there, but it’s not what it was before.”
FIU’s study used data collected between 2001 and 2016 by the Florida Coastal Everglades-Long Term Ecological Research Program.
Price said the dry season is when damage from sea level rise is the highest as water managers juggle the needs of South Florida’s communities, farms and natural areas.
The South Florida Water Management District, which covers a 16-county region from the Kissimmee River basin to Florida Bay is working to get more freshwater moving south because it’s not just sawgrass that’s thirsty.
South of Everglades National Park’s Shark River Slough, where FIU’s study was based, sea grasses in Florida Bay thrive in a more brackish environment. But too much salinity can mean a widespread die off, something that happened in 2015 when a drought led to salinity levels in Florida Bay that were twice as high as in the ocean.
“Historically, even during drought, the system was so large and stored so much water, it buffered Florida Bay from having this kind of die-off behavior,” said Fred Sklar, a South Florida Water Management District scientist who studies water flow in the Everglades.
An emergency measure approved in 2017 by the water management district’s governing board initiated several projects to increase the amount of freshwater flowing into Taylor Slough, which is southeast of Shark River Slough, and on to Florida Bay.
Despite the “significant” increase in freshwater, Sklar said he doesn’t know if it will be enough to end seagrass die offs. Warming ocean temperatures are also a problem because they lead to an increase in algae that can suffocate seagrass.
Price would like similar emergency measures taken for Everglades National Park to curtail sawgrass damage.
“They can change the water schedule now,” she said, although she acknowledges the water needs to be cleaned of high nutrient levels before it can go into Everglades National Park. “Where there’s a will, there’s a way.”
Water management district spokesman Randy Smith said the FIU study is under review and that an update on sea level rise and how it relates to controlling water in South Florida will be made at a spring board meeting.