Episcopal AP Environmental Science (APES) students are growing life from cement as they continue supporting Northeast Florida’s oyster populations through a hands-on, sustainable build project using Pervious Oyster Shell Habitat (POSH) structures. This exciting environmental project has now been underway for more than two years in APES classrooms.
Over this time, APES faculty member David Wandel has teamed up with Dr. Rafael Crowley, professor of coastal and port engineering at UNF, and Jimmy Tomazinis, Florida Department of Environmental Protection (FDEP) Northeast Florida Aquatic Preserves Manager, to help construct and place POSH units throughout Northeast Florida.
The first official year of the project, 2024, served as “an experimental year to familiarize ourselves with the process enough to walk students through making their own POSH, and it was a success. There are a whole host of environmental benefits to an artificial oyster reef. The POSH structures are really revolutionary when it comes to artificial oyster reef construction,” said Wandel.
Oyster larvae love tiny, protected spaces, and structures made from recycled shells coated in cement create a super-inviting home. Once they settle and attach, they grow, and produce more larvae that do the same. Oysters play a huge role in keeping waterways healthy. They naturally filter nitrogen from the water, reduce shoreline erosion, boost biodiversity, and their shells even form extra habitat for all kinds of marine life.
“Oyster reefs and population growth cross into many APES topics: biodiversity, ecosystem services, food chains and food webs, habitat loss, eutrophication, erosion, wetlands, commercial fishing, etc. Oysters are a keystone species in Northeast Florida,” said Wandel. “Oyster reefs provide habitat for the fish, shrimp and crabs that support recreation and commercial fisheries in our region; they can reduce shoreline erosion which can minimize sediment pollution in the river; and they sequester nitrogen pollution in our water. This project is also a way for our students to engage in an environmental solution project and get a real world example of what we’re learning.”
This year, students are building one POSH every week, and the momentum will continue throughout the spring. Each POSH weighs about 30 lbs and is about 18 inches wide and six inches high. So far, Episcopal students have created about 26 POSH. Approximately 18 of these have already been placed in the Ribault River. New POSH are awaiting a permit for placement.
“We’re proposing placing them in lines, five in a group, with space between each group. The permit I’m writing aims for us to place about 180 feet of oyster reef. Each wild oyster that grows on our reef will filter about 50 gallons of river water in a day,” said Wandel.
The POSH construction process is completely hands-on. Students load a small cement mixer with used oyster shells donated by local restaurants, add water and a sprinkle of cement to coat every shell, and while that spins, the inside of an octagonal POSH mold gets brushed with vegetable oil to make removal easier later. Once coated, the shells are poured into the mold to dry. After about seven days, the shells are fully set and the mold can be removed—creating a new POSH.
“Creating POSH will most likely become an APES tradition. Oysters are such a critical and important part of our ecosystem and these modules are such an easy way for students to not only have an impact on their environment but also create something permanent that will continue to grow in size and impact as more and more oysters colonize our POSH,” said Wandel.