Benefits of Oyster Reef Restoration

More than 30 million pounds of cultch were used to construct a series of patch reefs (small, isolated reefs) within the St. Lucie and Loxahatchee Estuaries. Cultch is fossilized shell, lime stone rock, recycled concrete rubble, and other hard materials designed to provide points of attachment for oysters. When fully populated with oysters, the constructed reefs in the St. Lucie River will provide enough oyster habitat to filter the total volume of the Estuary in just one month. These reefs also provide essential habitat structure for other species, including shrimp, clams, crabs, snails and a variety of fish, including many economically important species such as gag grouper, gray snapper, sheepshead and red drum.

To determine the best locations for the reefs, a comprehensive survey was conducted to measure muck layer depth, salinity levels, water quality, past existence of oyster beds and other characteristics. The sites that were chosen have suitable conditions for the placement of cultch and for oyster spat recruitment. Spats are oysters that have just settled to the bottom, hopefully finding some structure (prop roots, dock pilings, oyster shell, and natural rock) where they will attach and grow. 

Plantings of mangroves and other shoreline species were also placed inshore of some of these restored reefs, reducing shoreline erosion and resulting in less sediment deposits in the estuaries. Oyster reefs and shoreline plantings also provide much needed substrate for oyster spat recruitment.

Benefits of Oyster Reef Restoration

Oyster reefs are a complex ecosystem providing habitat for over 300 species of invertebrates such as shrimp, crabs, clams, snails, and worms as well as many fish species. The communities inhabiting oyster reefs form the base of an estuarine food chain which provides forage for many important fish species such as snook, sheepshead, grouper, red drum, spotted sea trout and black drum. Many fish species that live as adults on the offshore reefs spend the juvenile phase of their life cycle on oyster reefs.

Oysters are filter feeders, meaning that they take in the surrounding water, filter out and consume the plankton and microorganisms inhabiting that water, and release the filtered water back into their environment. An adult oyster can filter 20 to 50 gallons of water per day.

An extensive and healthy oyster reef plays an important role in cleaning the water within an estuary. Clearer water allows greater penetration of sunlight which can lead to expansion of seagrass beds which are another important habitat within a healthy estuary.

  • The reefs will provide essential habitat for oysters and many other species including shrimp, clams, crabs, snails and a variety of fish.
  • When fully populated with oysters, the reefs will be able to filter the total volume of the St. Lucie Estuary in about one month.
  • Improved water quality will lead to expanded seagrass growth which creates important fish nursery habitat.
  • Once the habitat “infrastructure” is in place, if oyster mortality occurs due to Lake Okeechobee releases or natural storm events, oysters will be able to repopulate more quickly. Past monitoring studies in the St. Lucie Estuary have shown this regeneration can occur in as little as one year.
  • Oyster reefs, along with mangrove and other plantings, will serve as effective shoreline stabilizers.
  • The marine industry is a significant economic engine in southeast Florida and the health of the marine environment is inextricably linked to the health of our economy. Improved water quality and increased habitat will benefit both commercial as well as recreational fishing and boating.
  • Many local jobs ranging from marine construction to scientific research will be safeguarded, and additional jobs created, through the duration of the project.

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