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.