Oyster Prisms a Plastic-Free Alternative to Oyster Restoration

Interested in marine habitat restoration? What about using oysters to improve water quality and reduce shoreline erosion? A workshop was held at Rookery Bay on Wednesday April 20th to demonstrate how to create structures called “oyster prisms” as a plastic free alternative to traditional oyster restoration. 

This hands-on workshop involved area volunteers creating prism structures that oysters will naturally recruit to and provide their valuable ecosystem service for a restoration site in Rookery Bay.

The workshop was led by Michael Sipos, a University of Florida Sea Grant Extension Agent, who manages the Collier County Sea Grant Extension Program, which is a partnership between the University of Florida's Institute of Food and Agricultural Sciences, Florida Sea Grant and Collier County.

Michael has been the Florida Sea Grant Extension Agent in Collier County since late 2019. UF focuses on oyster restoration with a new project aimed at reducing plastic use in oyster restoration. 

This project is called the Partnership for Plastic-free Restoration of Oyster Shorelines, or PROS for short. This is a network of practitioners, educators, and local government partners who work toward implementing living shoreline projects using a newly developed plastic-free material called reef prisms.

Living shorelines (coastal erosion control using native vegetation and other natural elements) are increasing in popularity as practitioners and homeowners learn about their many benefits. However, one of the most common living shoreline approaches – creating reefs by stacking up rows of “shell bags” (oyster shells contained in plastic nylon mesh sacks) – is highly problematic for shoreline restoration applications. This is due to the likelihood that the plastic mesh releases harmful microplastics into the marine environment and the concern that wildlife could become entrapped or entangled, especially as bags break down or if the reef project fails to establish.

Oyster shell bags have many advantages:

• They are cheap to produce.

• They are easy to build and deploy using volunteer assistance.

• They offer a high degree of flexibility in project design (i.e., can stack in any configuration).

• They have a history of proven success in many states.

The development team at the University of Florida, led by Dr. Mark Clark, spearheaded the creation of reef prisms. They wanted a modular, plastic-free alternative to shell bags that staff could also build and deploy with volunteers using affordable and readily available materials. 

Reef prisms are made from a combination of jute-fiber erosion control mats and a rapid setting, low-shrink grout available from local big box stores. The chemical formulation of this grout allows for roughly 7x higher break strength and a 35-50% lower carbon footprint, a more neutral pH (8.5 vs. 12.1), and significantly faster setting time in comparison to Portland cement. 

As interest in reef prisms mounted, UF/IFAS Extension and Florida Sea Grant brought organizations across Florida together to form the PROS Community of Practice through a grant from the Florida Department of Environmental Protection. 

This group of living shoreline practitioners will work toward implementing living shoreline projects using reef prisms in different water bodies. The reef prism development team is responsible for the overall project coordination and technology transfer as living shoreline sites are selected and planned. Local governments, non-profit organizations, and UF/IFAS Florida Sea Grant Extension Agents are responsible for identifying the demonstration site locations and strengthening partnerships. 

The reef prism process and material are fully open-source and available for any organization to adopt and apply for free through joining the PROS Community of Practice. 

Of course, we all know the history of Marco Island as a major source of shellfish and clams early in the 20th century. The clams were almost completely wiped out by the Doxsee Clam Company by 1935. There is still a large portion of the 10,000 island that is designated as a reserve for shellfish harvesting. Collier Bay on Marco Island has an oyster bed along the north shore of this bay.

Would an oyster restoration be viable in Marco’s waterbodies?