The county plans to use oyster-filled Reefballs over Enteromorpha at the North Causeway Island with the goal to producen a net gain in Essential Fish Habitat. St. Lucie County intends to put Reefballs in intertidal areas at the North Causeway Island and fill them to varying heights with oyster shell (to increase habitat variability).
The algae surrounding the North Causeway shoreline has been positively
identified as Enteromorpha, not Ulva. While Enteromorpha is not
free-floating, it is held in place by a holdfast rather than a root. It is
an opportunistic species used as an indicator of highly eutrophic waters.
Because its holdfast does not extract nutrients from the sediments,
Enteromorpha is capable of colonizing other surfaces (i.e. rocks, mangrove
roots, wood). Placement of reefballs in the intertidal zone will be rapidly
colonized by Enteromorpha, which is capable of withstanding tidal
fluctuations, resulting in no net loss of the functions and values of the
algal community.
Placement of the reefballs, along with oyster shell, and possibly mangroves
will not only add additional EFH, but stabilize sediments beyond the
capability of Enteromorpha alone. The species richness developed in our test
modules (mesh bags filled with oyster shell) will also contribute to
ecosystem stability as oyster shell will be placed inside the reefballs.
Live oysters have been observed growing on red mangrove prop roots in nearby
areas. Reefballs will be used to test whether adding intertidal profile will
enable colonization of oysters. The addition of a profiled substrate may
also make measurement of vertical growth of oyster colonies easier to
document.
Location:
St. Lucie County may be applying for permits to place Reefballs near the shoreline along the North Causeway Island (see oyster module location map -station 9) in Fort Pierce. There is a public finger pier in this area that was constructed by the County; we hope to apply to put Reefballs under this pier as well.
