Environment

Dying seagrass and ‘yellow fog’ signal trouble for Florida Bay

Yellow fog spreads across Florida Bay

As Florida Bay wilted over the summer during a deepening drought, scientists arrived to find miles of dead seagrass smelling like rotten eggs in a cloud of yellow sulfide. They suspect hot, salty water from adjacent mud banks slid into the bay and
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As Florida Bay wilted over the summer during a deepening drought, scientists arrived to find miles of dead seagrass smelling like rotten eggs in a cloud of yellow sulfide. They suspect hot, salty water from adjacent mud banks slid into the bay and

The seagrass in Florida Bay is dying, a sign that the ailing bay could be going from bad to catastrophic.

Years of flood control on top of a prolonged drought wilted the bay over the summer, making already hot water twice as salty as it should be. When scientists hustled out to investigate last month, they found miles of dead seagrass: up to six square miles in Rankin Bight and seven square miles in meadows around Johnson Key, a flat once famed for redfish and snook. A cloud of sulfur had spread in water just off the Flamingo Visitor Center, leaving behind a stinky stain scientists call “yellow fog.” It may cover 25 square miles already.

But what really concerns them is this: The last time the bay looked this bad, a massive algae bloom followed. The bloom lasted for years, turning gin clear water a sickly pea green and unleashing a scourge in Everglades National Park that anglers and scientists still regard as a turning point for the bay.

Imagine if a third of Yellowstone National Park suddenly died.

To emphasize the severity of conditions, scientist Fred Sklar, who monitors the Everglades for the South Florida Water Management District, titled a presentation made last month, “Florida Bay Conditions: Another Perfect Storm?”

“I don’t think there’s anything we can do to stop this. The question might be, is there something we can do to slow it down,” he said. “The train is moving and the only thing we can do is put roadblocks in the way.”

Seagrass scientists who began monitoring the bay in 1995 after the unprecedented bloom threatened to derail the region’s $723 million fishing industry are just as worried.

“It looks like this die-off will be every bit as extensive as the episode in the 1980s,” said Paul Carlson, a marine ecologist with the state’s Fish and Wildlife Research Institute in St. Petersburg, who investigated the earlier crash. “There’s places where dead turtle grass … covers the bottom a foot deep.”

And it’s not just the grass that’s suffering. In July, when salinity peaked at 65 parts per thousand, toadfish that lurk on the bay bottom waiting to ambush prey died in Rankin Bight, said Chris Kelble, an oceanographer with the National Oceanographic and Atmospheric Administration.

“My hypothesis is they don't swim away like other fish and the double whammy of extreme high [salinity] and temperature just took them out,” he said.

As Florida Bay wilted over the summer during a deepening drought, scientists arrived to find miles of dead seagrass smelling like rotten eggs in a cloud of yellow sulfide. They suspect hot, salty water from adjacent mud banks slid into the bay and

This year’s winter fish counts turned up no freshwater minnows, the first link in a complicated food chain. Sea trout, a fish perfectly engineered to reflect the health of the bay, failed to show in last’s year count. Researchers caught juveniles this year, but in numbers “nowhere near where they should be or where their numbers have been in the past,” Kelble said.

How the bay got to this point is as much about human meddling as mother nature. For decades, water managers have been struggling to undo damage from the C-111 canal, which was built in the 1960s to barge rocket engines from Homestead to the coast. It shifted a vital flow of Everglades water away from northeast Florida Bay.

Another factor also may be at work: climate change.

With models showing a 10 percent to 20 percent decrease in rainfall over South Florida, heat waves and droughts will likely become more common, making water scarcer and creating Florida Bay’s equivalent of a California wildfire. Climate forecasts also call for fewer hurricanes, which help flush out salty water by stirring up the bay.

“It’s just like the fire analogy in the west,” said Ben Kirtman, a climate scientist at the University of Miami’s Rosenstiel School for Marine and Atmospheric Science. “The water managers will have to make decisions based on that.”

And that means the fight for water — and whether to save the fish or keep the farms or both — could become more heated.

“That’s sort of the elephant in the room that we don’t really talk about,” he said.

Because it is such a complex ecosystem, scientists have struggled to understand how to fix the bay. At 850-square miles, it is actually made up of about 24 different basins, divided by mud banks. Each basin has its own distinct level of salinity, influenced by water from the Everglades, the Gulf of Mexico and the Atlantic ocean, along with years of man-made changes going back to Flagler’s plans to build a railroad across the bay and drain coastal marshes in an attempt to lure ranchers to the mosquito-infested wetlands. Knowing the right mix of groundwater and surface water could be the key to keeping salinity in check, Sklar said. But so far, the balance remains uncertain, he said.

What scientists do know is that to avert an algae outbreak, they need to get it right before time runs out. In the 1980s, a massive die-off spread across five basins. Five years later, an algae bloom unfolded. Most likely, the dead seagrass loaded the shallow bay with nutrients that triggered the bloom.

It took more than 12 years for the grass, considered a key indicator of the bay’s health, to begin recovering. The grass also is critical to maintaining the ecosystem: The rolling meadows provide food and shelter for sea life and stabilize the muddy bottom to keep water clear.

“These kinds of things have probably been happening periodically over time,” said Margaret “Penny” Hall, a state seagrass expert overseeing a team investigating the die-off. “It’s not a new phenomenon, but there was a perfect storm where it took off in 1987, probably exacerbated by water management decisions.”

After the 1980s disaster, the state began monitoring 17 spots in the bay, trying to understand what set of conditions might trigger a die-off. They focused on turtle grass, which was hit hardest and grows more slowly, and shoal grass, which can grow faster in harsher conditions. Knowing which grass grows where can give them a good idea of what’s going on in the water. In 1997, as grass began recovering, researchers found the amount of shoal grass had taken over western Rabbit Key basin after the turtle grass died. Overall, shoal grass more than doubled, an indication of harsher conditions.

Over the summer, on the heals of a dry winter that spiked salinity in Taylor Slough, a biologist at Everglades National Park spotted what she suspected was the beginning of a die-off and contacted the researchers who had studied the 1980s event, Carlson said.

When Hall’s team got there, they found two of the five basins hit hardest in the 1980s dead or dying. A third showed signs of trouble.

They think this is what happened: Without rain, the hot water turned saltier and heavier, creating a kind of lid, trapping sulfur in mud and keeping oxygen out. Seagrass can normally tolerate low levels of sulfide, the sulfur that occurs naturally in the mud. But the higher levels caused it to die. Once dead, the decaying grass released even more nutrients and continued the cycle.

“The sulfur is both cause and effect,” Carlson said.

Had more restoration projects been complete, scientists believe the extra water would have helped buffer the harsh drought. But lack of funding, bureaucratic delays and the demands of competing interests have delayed work that might have brought more water south.

This summer, for example, when the U.S. Corps of Army Engineers announced plans to conduct a two-year test on a series of canals, gates and flood control structures to restore water flows, the agency enraged environmentalists by opting for a plan environmentalists say favored farmers. The Corps decided to continue using a pump to keep farmland dry, a decision the Everglades Law Center called as “arbitrary and capricious as it is based on unsupported assertions.”

“We should be doing everything we can to benefit the bay right now,” said staff attorney Julie Dick. The Corps was unable to say whether an environmental study would be done when reached late Friday.

Even with restoration, park superintendent Pedro Ramos said the bay “relies on higher rainfall, which we have not been getting.”

And given climate change projections, he worried that keeping the bay healthy will become only more difficult.

“Things are changing for sure,” he said in a text message. “New territory for everyone, including scientists, and weather seems to just be getting more and more difficult to forecast.”

Recent rain — September had more than 10 inches — may have helped some, but it also changed conditions too quickly. Monitors at Buoy Key show salinity in parts per thousand dropping from the mid 40s to the high 30s in the last few days. Normal ocean conditions are 30 parts per thousand.

But scientists worry the bay is already in a downward spiral — and anglers have long reported seeing fewer fish.

“It’s the largest fish kill I’ve ever seen in the park,” said Capt. Dave Denkert, a guide who has fished the bay since the 1970s and spotted dead pinfish and snapper throughout the summer. “It goes from real salinity to almost completely fresh. It’s extreme one way and extreme the other. It all has to come together.”

When conditions go bad, some fear the fish will simply leave. Already the stock of bonefish, a catch that draws anglers from around the world, are “below the 30 percent threshold considered sustainable,” said Jerry Ault, a University of Miami fish ecologist, who warned that Florida Bay may be a microcosm of bigger problems to come.

“You get to where you really listen to the fishermen because they’re usually the first ones to find something wrong,” Hall said. “They may not know the name of the seagrass, but they know what it looked like.”

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