| Research Program: 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.
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