Can oysters help save Biscayne Bay? A new restoration effort aims to find out
The conversation about oysters started at the dinner table.
A massive fish kill in Summer 2020 had left the shores of Biscayne Bay chock-full of dead sea life. Some were surprises to even the most avid bay-goers, like tiny baby eels, rare and colorful fish and a species long considered functionally extinct in the north bay — oysters.
Alberto “Tico” Aran sat around his parents’ dining room table and talked about the massive loss, a vivid reminder of the rapidly declining health of the bay due to low oxygen, high pollution and the die-off of vital sea grasses. He wondered why no one was talking about oysters as a solution.
More than just delicious, oysters have the ability to filter pollution from the water they grow in. Oyster beds are also useful tools to protect coastlines from hurricane-driven storm surge. They’re employed in restoration efforts along both of Florida’s coasts, and now — thanks in large part to Aran — in Biscayne Bay.
Oysters used to be quite common in Biscayne Bay. An 1896 report referred to “a luxuriant growth of oysters” in the bay, and there was even an active oyster fishery in the north bay until Haulover Cut was constructed in the 1920s.
“Now the population is at 1% of what it used to be,” Aran said.
Aran isn’t a marine biologist or even a scientist. He and his wife run Miami-based Radiate Kombucha, and he used to own his own tea business. But he’s a Miami native and has spent much of his life fishing, swimming and boating in the Bay. He saw an opportunity to make a difference and took it.
He has quickly found scientists willing to answer his questions, restaurants willing to donate their leftover oyster shells, a small army of volunteers and thousands of dollars of community funding. He called his venture the Watershed Action Lab.
“Instead of taking 100 years for them to maybe naturally set up shop in these little pockets, we want to bring in the human element to assist them and make that maybe three or four years,” he said.
Harnessing the power of filter feeders
When scientists develop plans to repair ecosystems like the bay, they set goals for what success looks like. In Biscayne National Park, one of those express goals is the revival of oysters. In a 2006 report, scientists talked about how increased flows of freshwater to the bay could make it more oyster friendly.
That’s because the filter feeders need a very specific mix of fresh and saltwater, as well as enough oxygen, to succeed. Aran found that in urban Miami, the Goldilocks zone for oysters was the Coral Gables Waterway. His understanding is that there’s not enough oxygen in Little River, and the Miami River is too polluted.
On a recent kayaking trip down the waterway, he stopped over and over to point out flourishing colonies of various species of shellfish.
At first, near the Biltmore Golf Course, he found the occasional freshwater mussel. Farther down the canal, clumps of oyster shells cling to the limestone rock. At one point, they were densely packed on every single bridge and dock piling. As the mix of fresh and saltwater began to lean salty, the eastern oyster variety grows more scarce and a thinner variety known as flat tree oysters takes over.
“The eastern oyster has been the focus,” Aran said, “but any filter feeder is good. Obviously, the flat trees do something, it’s better than nothing.”
Exactly how much they clean, however, is still up for debate, said Ana Zangroniz, a Florida Sea Grant extension agent for Miami-Dade County who has helped answer some of Aran’s questions.
“We know that they’re filter feeders but how do those species compare? Especially considering they vary in abundance,” she said.
Another scientist Aran has turned to for information, Ashley Smyth, an assistant professor in biogeochemistry at the University of Florida, said the classic statistic for an eastern oyster is that it can filter 50 gallons of water a day, but that’s based on oysters in ideal conditions in Maryland and Virginia.
“That’s not exactly what we have down here, or it might be. Having local relevant data is important,” she said. “We have a lot of questions to be answered before we know if oysters are going to save the bay.”
Smyth is also leading a project to look into how oysters and other shellfish can improve water quality in the Guana Lake and Guana River in St. Johns County. Smyth and colleagues got a $595,000 grant for the multi-year project that started in April.
“Normally, this area would be pristine, but nitrogen and other nutrients have found their way into the system, leading to algal blooms and low oxygen in the water, with consequences for oysters and mussels,” she said.
This protected estuary is home to rich marshes, mounds of mussels and live oyster reefs. The estuary’s dam separates the river from Guana Lake. Over the last few years, a community-supported, multi-agency monitoring effort revealed that the estuary is showing signs of pollution.
“The heart of all of this is that there is a water quality problem causing deterioration in the ecosystem that people enjoy, where wildlife thrives, and that benefits the environment and economy. This research will help the community develop restoration and management plans,” Smyth said.
Elsewhere in Florida, The Nature Conservancy in June launched the Pensacola East Bay Oyster Habitat Restoration Project to boost oyster populations in East and Blackwater Bays. It’s the largest estuarine habitat restoration project by the nonprofit in Florida, funded by a $15 million grant from the National Fish and Wildlife Foundation through funding from the criminal settlement of the Deepwater Horizon oil spill.
The project aims to place 33 oyster reefs along approximately 6.5 miles of Santa Rosa County shoreline, to return oysters to a region where they historically thrived but have declined over the past few decades.
“Oysters play a vital and often overlooked role in the health of our estuaries, our fisheries and our economy,” said Temperince Morgan, executive director of The Nature Conservancy in Florida.
The community gets involved
On Sunday in Coconut Grove’s Kennedy Park, dozens of volunteers carefully piled sunbaked oyster shells on a blue tarp in the grass to spell out “Save Biscayne Bay.” Then they got to work.
“We try to do everything we can for the environment, “ said Rebecca Stacey, a 17-year-old student at St. Brendan High School, as she cut and coiled 10-foot lengths of rope. “Usually just beach cleanups.”
Her friend, 17-year-old Tommy Dugue, used a drill to punch holes in the thousands of oyster shells, readying them to be strung like beads on a necklace on Stacey’s ropes. The idea is to mimic mangrove roots and give oysters a habitat that gets exposed to air and water as the tide changes.
“This was something different,” Dugue said. “It’s a cool way to actually fix the bay.”
The volunteer effort, the first of several planned, was Aran’s first. He tried the idea of stringing up leftover shells on a piece of rope and dangling it off his parents’ dock near Matheson Hammock last summer. He said the creation of new, improved habitat for the few oysters that survived in the area has led to a population explosion in the zone around his small experiment.
Now he’s trying to scale up. With the help of a $6,500 grant and hundreds of community donations on a science crowdfunding website, Aran was able to raise more than $15,000.
Miami restaurants Kush and Michael’s Genuine agreed to hand over their oyster shells, and Aran has since piled tens of thousands of them in his backyard to “cure” in the hot sun for months.
Now volunteers are busy stringing them along ropes, ready to be hung from docks along the Coral Gables Waterway. To complete the permits he needs for the project, Aran is still looking for homeowners along the waterway willing to volunteer their docks and use their addresses on the Florida Fish and Wildlife Conservation Commission Permits.
With those secured, Aran’s fleet of volunteers can start deploying the ropes full of oyster shells along the waterway and at the Deering Estate. After a few months, they hope to harvest some of the baby oysters in the more successful spots and use them to colonize other areas.
“A big part of the community effort is we need people in kayaks everywhere to find these little pockets,” Aran said. “Everyone can play a role in saving the bay.”
Miami Herald reporter Adriana Brasiliero contributed to this report.
