Aspects of Oyster Ecology and Their Utility in the Design of Estuarine Restoration Projects in the Greater Everglades: Example from Southern Golden Gate Estates
Greater Everglades restoration projects concern both terrestrial and estuarine habitats and focus on entire watersheds. Under guidance from the U.S. Army Corps of Engineers and the South Florida Water Management District, restoration planning follows a strict protocol. The American oyster, Crassostrea virginica, is being employed in numerous steps within the protocol: as a bioindicator of estuarine health, as a tool for establishing restoration targets, and as a measure of estuarine restoration effectiveness. This presentation reviews the protocol employed, demonstrates the utility of oyster ecology to this process, and lastly illustrates its application by reviewing the Southern Golden Gate Estates (SGGE) project that presently awaits Congressional authorization.
The protocol adopted for Everglades restoration consists of 9 steps: (1) defining restoration goals, (2) characterizing current conditions, (3) establishing the pre-alteration state, (4) designing alternative restoration scenarios, (5) establishing performance measures and targets, (6) modeling to evaluate each scenario; (7) designing a restoration monitoring plan, (8) implementing a restoration scenario, and (9) initiating adaptive management. Oysters and their reef communities are being used in steps 2, 3, 5, and 7. Various aspects of oyster physiology and ecology, including growth, standing stock, recruitment, susceptibility to disease, living density, the aerial distribution reefs, and the composition of the reef community, serve as bioindicators of estuarine health (step 2). These aspects are compared using a spatial homologue approach, whereby geomorphologically similar positions along the estuarine axis are compared among estuaries. Step 3 is achieved by comparing the present distribution of reefs with pre-alteration surveys or by inferring paleosalinities using stable isotope and trace metal geochemistry of subfossil oyster shells. The same aspects of ecology are used to define targets and performance measures for restoration (step 5). Targets are defined for specific homologues using conditions in the neighboring, pristine estuary. Finally, restoration success can be gauged (step 7) by how close the system approaches a given target.
SGGE is a failed housing development project that disrupted freshwater sheetflow through the building of extensive canal and road systems. Current water management practices have reduced freshwater input due to beheading in most of the receiving estuaries and freshwater inundation due to canal-fed drainage in Faka Union Bay. Comparisons of oyster reef distribution, living density, and the prevalence of the disease DERMO among homologues within the effected estuaries and Fakahatchee Bay, a pristine estuary immediately east of the sheetflow disruption, demonstrate the effects of altered salinity and temperature. The preferred restoration alternative was one whose hydrologic modeling provided the correct distribution of salinities for oyster health.
Aerial photograph showing the distribution of modern, intertidal oyster reefs (in yellow) within northern Estero Bay and the Hendry and Mullock Creek watersheds. The survey was conducted by helicopter during times of extreme low tide in the winter. Reefs were photographed and locations were ground-truthed.
For more information contact:
Coastal Watershed Institute
Florida Gulf Coast University
10501 FGCU Blvd South
Fort Myers, FL 33965 Phone: 239.590.7165 Email: