An osprey perched 30 feet above the water in the leafless limbs of a dead Australian pine scans a narrow section of the Estero River, looking for an evening meal. A great blue heron squawks in the distance.
Dozens of mullet, fattened for the spawning season, cruise the clear waters in small schools, some fish leaping out of the water and splashing back down in classic mullet fashion. Blue crabs scurry along a nearby sandbar, attempting to avoid predators while at the same time foraging for their own sustenance.
Here the Estero River forks near Calusa Blueway marker 27, a sign that directs paddlers along the county's eco-friendly waterway trail.
Red mangrove tunnels lead to creeks and tiny bays, giving visitors and wildlife a chance to enjoy a relatively remote section of what was once part of the historic Everglades, the famed River of Grass.
This particular spot — about a mile upstream of Estero Bay — may be the prettiest locale on the entire river. It seems like a great place to start a family, at least oysters and marine scientists think so.
Aswani Volety, a professor at Florida Gulf Coast University, and a group of volunteers have made several trips to this scenic section of the river, working to re-establish oyster bars that may have flourished here for centuries.
Pollution draining from urban areas into the bay's watershed — a geographic area that includes San Carlos Park, Estero, Bonita Springs and even Corkscrew Swamp Sanctuary — has shrunken local oyster beds and completely wiped out reefs in other areas of the estuary.
Volety's group of 80 scientists, FGCU faculty and students — as well as anyone who wants to sign up — spent Saturday building onto an oyster reef first established nearly three years ago. The first construction worked, and Volety expects the latest addition to provide even more habitat for hundreds of species that make use of the bars.
"It's actually doing real well," Volety says of the original creation. "It's all completely covered, and it's one reef."
The oyster bags are visible just below the surface in a relatively deep and fast-following section.
"They make the water clearer and sunlight can get to the bottom to allow sea grasses to grow," Volety says, explaining other positive aspects of reinvigorated life.
Oysters form a vital foundation in estuary life. A single oyster can filter more than 250 gallons of water a day, and the reefs provide necessities for hundreds of animals.
"Oyster reefs harbor more than 300 aquatic species for either food, shelter or habitat," Volety says. "They also provide 50 times the amount of surface than a flat bottom with all the nooks and crannies."
The oysters and other shells used to construct the reefs come from mining pits. The debris is dumped on the FGCU campus, bagged into mesh sacks weighing 20 to 40 pounds and taken by flatbed trailer to the Carl Johnson Boat Ramp at Lovers Key State Park.
From there the sacks are loaded onto boats and taken to the river. Once on the river, scientists and volunteers strategically place the sacks near the original bed, creating a mound of old shells that are designed to provide a hard surface for oyster larvae to attach to and flourish.
The real work started at the boat ramp, where Anica Sturdivant holds a 30-pound mesh sack of shells early Saturday morning. She is working as part of a 80-person strong chain of volunteers handing the heavy bags to one another in bucket-brigade fashion.
Claiming the first slot in the human conveyor belt, Sturdivant waits patiently for the production line to kick into gear. But instead of just dropping the sack, or at least sitting it on a nearby rail to ease her physical strain, she cradles the bag like a newborn infant, almost guarding the oysters, like a running back poised to dive into the end zone.
Maybe the discarded shells deserve such protection, since they form possibly the most critical link in Southwest Florida's estuaries.
Conditions must be just right for oysters to establish a reef or expand. The water must be relatively clear, with a brackish mixture of fresh and saltwater. Water clarity is another key, as is a nearby source of larvae offspring.
Win Everham is a professor at FGCU and an active member of the Estero Bay Agency on Bay Management, a non-regulatory group that oversees development within the Estero Bay watershed.
"One of the things we've learned is you can't just put the oysters anywhere," Everham explains. "There has to be a good mixture of brackish conditions and good substrate (underwater surface). The larvae need something hard to adhere to. There also has to be a nearby source of larvae or nothing will ever grow on the (dead) shells."
For Sturdivant, a San Carlos Park resident and Florida Gulf Coast University graphic designer, the outing is more than a way to help establish oyster beds destroyed by poor water quality. She's also using the project as a science lesson for her daughter.
The family plans to plant an oyster bar inside a drainage culvert in San Carlos Park, an area that's known for sending large, harmful freshwater flushes into Estero Bay. If the oysters live, they would enhance water quality and habitat in the ditches and canals leading to Mullock Creek — and eventually Estero Bay, the state's oldest protected aquatic preserve.
"We're going to look at what it does to improve water quality," Sturdivant says as her 11-year-old daughter, Mariah Coughlin, takes a break from hauling sacks. "We already have lots of wading birds and some fish. If we had more fish, we'd have more birds."
Caitlin O'Rouke, also 11, goes to Bonita Springs Middle School with Coughlin. The two plan to start working on their own oyster project this week.
"This is so awesome," O'Rouke says while standing on the boat ramp. "I just like marine biology and that's what I want to be when I grow up. So this is exciting."