Save it or lose it: As seagrass vanishes, a mass death of marine life and a brown-water future
Editor’s note: This story is the second installment of a two-part series on the catastrophic seagrass die-offs plaguing nearly all of Florida’s coastal waters. The die-offs persist, raising the question — can 21st century Florida and seagrass coexist?
In the timescale of ecosystems, the collapse of Florida’s seagrass has been sudden, severe and nearly simultaneous.
A tragic consequence unfolded in 2021 and 2022, when about 2,000 manatees, or a quarter of the population in Florida, died. Most of the sea cows died in the Indian River Lagoon. And most died of starvation as their main food source, seagrass, had nearly vanished.
The vanishing seagrass fits a familiar recent pattern: Between 2011 and 2016, all five of Florida’s major estuaries, including the Indian River Lagoon on the east coast and Tampa Bay on the west coast, suddenly began to suffer seagrass die-offs. It’s unclear whether seagrass can survive what Florida has become in the 21st century. What has changed is the heat and the impact of humanity.
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The die-offs are tied to the building boom, agriculture and antiquated human waste-disposal systems. Add a bit more nutrients from a new development, or slightly hotter water from climate change, and entire seagrass meadows can collapse, leaving nothing but mud and algae.
Yet seagrass is part of Florida’s heritage, Florida’s appeal, Florida’s economy. The state is taking steps to stem the die-offs, but is it too little too late?
The Indian River Lagoon in distress
The Indian River Lagoon estuary system stretches along almost half Florida’s east coast — 156 miles from Stuart up to Ponce de Leon Inlet. The bulk of Florida’s east coast manatees migrate through the lagoon ecosystem in winter, many residing year-round. Yet the system lost 70% of its seagrass in the last dozen years.
Duane De Freese, executive director of the Indian River Lagoon National Estuary Program, which advocates for the watershed’s health, said the lagoon lost more than 46,000 acres, or 35,000 football fields of manatees’ main food source from 2011 to 2019 due to algae blooms and other stressors.
Locals and tourists accustomed to rotund and happy sea cows began to spot them weak and listing in the shallows, so thin they could see the outline of their ribcages.
The 2021 and 2022 rash of starving manatees kicked federal and state wildlife officials into emergency mode.
In the early winter of 2022 the Florida Fish and Wildlife Conservation Commission began to feed lettuce to hundreds of manatees as they gathered near a warm water discharge area of a power plant in Cape Canaveral.
So far, the plan has worked.
This past winter the feeding program continued, and there have been only 345 deaths so far in 2023, significantly lower than the five-year average for this time period, 511.
Back in 1980, when the state had a mere 10 million human residents, the Florida wildlife commission counted only 63 manatee deaths.
But feeding these 1,500-pound marine mammals is not a long-term solution.
Manatees routinely eat several species of seagrass, but with the seagrass die-offs statewide, and particularly in the Indian River Lagoon, they’ve had to shift their diet to algae.
Aarin-Conrad Allen, a biologist with Florida International University, analyzed stomach content from Indian River Lagoon manatee necropsies both before and after the recent seagrass die-offs.
The pre-die-off manatees ate about 62% seagrass and 28% algae. The post-die-off manatees ate 34% seagrass and about 50% algae.
Biologists suspect that algae is like junk food for manatees — an easy fix with low nutrition. Allen’s next study will compare the nutritional value to see if that’s true. If the emaciated manatees are any indication, he’s onto something.
Capt. Frank Catino, a fishing guide who’s been tricking sea trout in the lagoon near Titusville for nearly 50 years, said the bottom of the estuary in many areas is barren, and even “desert-like.”
He has seen the area, and the fishing, change tremendously.
“I see a tremendous decline in populations of fish,” he said. “This used to be the sea trout capital of the world. I mean, you went out, you threw a jig around, you caught ’em till you didn’t want to catch ’em. Ten-pound trout were not uncommon.”
Catino worries that expectations of estuary health have dropped so low that the new generation of anglers won’t know what a healthy estuary looks like. They won’t know what to fight for.
He also knows that seagrass isn’t exactly attention-grabbing.
In 2016 and 2021, the lagoon suffered algae-related fish kills that certainly were.
Thousands and thousands of dead fish, some of them trophy redfish, stacked up along the seawalls of the wealthy. “Until the fish died, nobody gave a damn,” Catino said.
He’d like to see more septic-to-sewer conversions, and for locals to use less fertilizer. “If you stop fertilizing, it costs you nothing!” he said.
Septic tanks can leach nutrient into groundwater, which eventually reaches the estuary, and those close to the water are vulnerable to sea-level rise. On top of that, aging municipal sewer systems spring leaks. Additionally, when storms and king tides flood sewer systems, that can dump plums of wastewater into the nearest bay.
Martin County, just north of Palm Beach County, is making great progress on septic-to-sewer conversions, De Freese said, but along the lagoon there are other issues inherent to Florida’s population boom. “We’re pushing so much freshwater off the land that, you know, 100 years ago, would have percolated through wetlands.”
In major rain events and hurricanes, wetlands and meandering creeks would have slowed the freshwater pulse to the lagoon.
Now that water rushes off parking lots and highways and roofs and into straight canals, beelining to the lagoon at high volume — just another stress on plants. At the south end of the lagoon each summer, polluted Lake Okeechobee runoff flows through the Saint Lucie River, killing seagrass beds near Stuart.
The runoff occurs when the Army Corps of Engineers feels the lake is dangerously high.
It has been dammed (and tragically breached by hurricanes) since 1915, starving the Everglades and Florida Bay of freshwater and forcing pulses of excess water east and west, into coastal estuaries near Fort Myers and Stuart.
The sheer volume of fresh water can kill seagrass beds, but the discharge also is full of nutrients that lead to saltwater algae blooms, and laced with blue-green algae, a freshwater algae that can release toxic fumes.
It coated the coastal community in neon-green slime repeatedly over the past decade.
Eve Samples, of Friends of The Everglades, lives in the area and said, “In 2018 we saw some of the blooms make it out to the beach. It was just incredible. So we’re on algae watch over here.”
Tampa and Sarasota Bay: success and collapse
Tampa Bay was once a seagrass success story.
It lost 90% of its seagrass from 1948 and 1982, but when the region reduced nutrient load significantly, algae blooms decreased, water cleared, and the bay flourished from 1988 onward.
“They had the patience for it to happen, I had the political will,” said James Fourqurean, seagrass expert from the Florida International University.
But a new collapse began in 2016. In the last six years the bay has lost nearly 30% of its grass, according to the Southwest Florida Water Management District. That’s some 11,500 acres, or 8,700 football fields. All told, the estuary has degraded back to 1988 levels.
Most of the die-off occurred in Old Tampa Bay, the upper reaches of the estuary that receive more runoff, more potential septic effluent, and less flushing from the ocean.
Sarasota Bay, just to the south, has lost approximately 26% of its seagrass in the last six years, and Charlotte Harbor farther south still, and vulnerable to Lake Okeechobee runoff via the Caloosahatchee River, saw a 23% loss in seagrass coverage between 2018 and 2021, according to the University of Florida.
Neither Tampa or Sarasota Bay receive polluted water from Lake Okeechobee, but they’ve been plagued by other calamities.
In March 2021, a leak at the Piney Point, a former phosphate processing plant, which sits on the eastern edge of Tampa Bay, prompted officials to release 200 million gallons of untreated acidic, nutrient-rich wastewater into the estuary.
A few months later, the bay saw its worst red tide since 1971, and the bloom reached farther into the bay than normal.
Red tide is a harmful bloom which can produce toxins that kill marine life — the city of St. Petersburg had to haul off 1,200 tons of dead fish from surrounding waters that summer.
It’s unclear that the events were related — red tide occurs naturally, but is also fueled by nutrients such as nitrogen and phosphorus. The bloom then blocks the sunlight that the seagrass needs. Tampa and Sarasota Bay estuary managers think the red tide could have exacerbated seagrass loss.
Some scientists are calling for more nuanced water testing that could detect blooms at the bottom of the bay.
Why are statewide die-offs happening now?
Some of the sudden collapse may come down to people and heat.
FIU’s Fourqurean said that there’s likely a nutrient tipping point that we’ve been creeping toward for decades. At first the seagrasses like the nutrients, but then at some point the algae beats them to the meal, and the oxygen, and the system collapses.
Climate change and the sheer volume of humanity in Florida — our lawns, our waste, our broken 20th century infrastructure — are stressors that just may inch the grasses over that fulcrum to collapse.
Florida is the fastest-growing state in the Union, with nearly 30,000 people moving to South Florida alone in 2022.
The population has close to tripled in 50 years, exploding from about 8 million in 1973 to more than 22 million, according to the latest U.S. Census figures. Experts expect the population to reach nearly 30 million by 2050.
Every person adds stress to the system, as does climate change and sea-level rise.
Climate change stresses the grasses in three ways: high water, runoff and heat.
Sea-level rise is encroaching on more and more sewer and septic systems, leaching nutrients into estuaries.
Extreme weather means more runoff. The National Oceanic and Atmospheric Administration says “extreme precipitation events,” such as the outlandish rainfall and flooding that hit Fort Lauderdale in April, when 26 inches of rain fell in a matter of hours, are trending up.
Climate change has been supercharging weather events around the globe, according to a 2023 report by the American Meteorological Society.
Those events can send overwhelming pulses of fresh, dirty water into estuaries.
And as you can likely tell, the heat is on.
Water this summer has been exceptionally hot. Consider:
On July 24, a buoy in Manatee Bay near Key Largo measured a water temperature of 101.1 degrees, possibly breaking the world record of 99.7 in the Persian Gulf.
Water temperatures Virginia Key reached 90.5 degrees this July (the average July temperature is 85.3). Temperatures there have risen consistently since since measurements began in the 1990s.
In Tampa Bay it reached 93.
“When you increase temperature, you increase respiration rate of everything in the ocean,” Fourqurean said. “And you decrease the amount of oxygen that can be held in the water. So there’s this temperature component of global change that will make the seagrass problems … much worse.”
Moving forward? Or backward?
Policies relating to seagrass under Gov. Ron DeSantis have varied. He has championed Everglades restoration, funneling $625 million for Everglades projects during the 2023 legislative session.
Unlike his predecessor Gov. Rick Scott, under whom the state’s Department of Environmental Protection years ago had been accused of banning the terms “climate change” and “global warming,” DeSantis has not shied from such discussions.
He created the Blue-Green Algae Task Force, which provides environmental recommendations to lawmakers, in 2019. And last year he added the Statewide Office of Resilience to address the impacts of flooding and sea-level rise.
And much to the delight of fishing guides and environmental groups, he bucked the Republican Party’s wishes and vetoed a bill in 2022 that critics said would have manipulated the flow of Lake Okeechobee water to favor the sugar industry and damage Everglades restoration.
This year, the 2023 legislative session included $800 million for water quality programs and $100 million to create the Indian River Lagoon Protection program, which adds water quality improvement projects and beefs up septic requirements and prohibitions in the watershed.
The 2023 budget also sent $850 million for the Florida Wildlife Corridor and a recurring $100 million for the Florida Forever land protection program, each of which will preserve open land that can slow the flow of stormwater to estuaries.
But several measures seem to contradict these steps.
DeSantis and the Legislature also approved what environmental groups, such as Friends of the Everglades, dubbed the “session of sprawl.” The most controversial bill could lead to more growth by silencing anyone who fights development: If a citizen challenges a change to a local comprehensive plan, such as building in an agricultural reserve, and loses, they must pay the legal fees incurred by the winning side.
There’s a full-on assault on “smart development” in Florida, said Eve Samples, of Friends of the Everglades.
She traces it back to 2011, when she said Gov. Rick Scott gutted the Department of Community Affairs and transferred its duties to the Department of Economic Opportunity. “The name tells you something about how the priorities shifted,” she said.
According to 1000 Friends of Florida, a nonprofit advocating growth management, the DCA challenged more than half the proposed changes to local comprehensive plans in the five years prior to Gov. Scott abolishing it.
As of 2019, the Department of Economic Opportunity objected or commented on fewer than 7% of proposed plan amendments.
Under Gov. Scott, the DEP, which enforces water quality standards, decreased enforcement by nearly 90%. Enforcement has increased slightly under DeSantis.
DeSantis also put a temporary stop to new fertilizer bans — more than 100 municipalities, including Broward, Palm Beach and Miami-Dade Counties currently use them to curb nutrient flow during the summer wet season.
The Blue-Green Algae Task Force, according to critics, may be toothless.
In 2019, it recommended a program to inspect and monitor the state’s nearly 3 million septic tanks. That never happened. The Department of Health says that while more than half the septic tanks in the state are at least 30 years old, fewer than 1% are inspected.
Saving seagrass will require a matrix of efforts, but there is one project that could have a profound impact, say experts such as Steven Davis of the Everglades Foundation, which advocates for ecosystem restoration.
That project is a pending storage reservoir and filtration marshes south of Lake Okeechobee.
The project, known as the Everglades Agricultural Area Reservoir, is part of the $23 billion Comprehensive Everglades Restoration Plan, and will drastically reduce polluted Lake Okeechobee flows to both Charlotte Harbor and the Indian River Lagoon, and send clean fresh water south to over-salted Florida Bay.
The Army Corps of Engineers broke ground on the project in February, but critics have raised concerns that it’s too small to do the job. The current plan is one-sixth the surface area of the original plan, at 10,000 acres, but it will be 23 feet deep, giving it two-thirds the carrying capacity of the original.
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Davis said the reservoir will be complete, if all goes well, by 2030, and will then need a few years of testing to ensure safety. He hopes to see water flowing south out of the filtration marshes by 2032.
Defining Florida’s future
So far, the 21st century may be great for Florida’s economy, but a disaster for Florida’s seagrass.
Though there have been improvements, the state laws and infrastructure are functioning, for the most part, much as they did in the past — but with more people and the ripple effect of a hotter planet.
Rising seas meet archaic sewer and septic systems, drawing even more pollution from the pipes and tanks.
Much of the deadly chemistry is happening underground, out of sight, or invisible, out of mind. Until suddenly a bay is barren. Until manatees ribs show under their skin.
Seagrasses have been around for 100 million years, and have come and gone from continents. The question is, do we want them around during our time here?
Capt. Benny Blanco, a fishing guide who spotted a massive seagrass die-off in Florida Bay, still frets daily about whether there’s just too much unfettered human impact for the seagrass to recover. “That really is where we are in history right now,” he said. “This is the moment — either we’re gonna save it or we’re gonna lose it.”
This story was produced in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the South Florida Sun Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times.
