Currently,
the only stable self sustaining native oyster populations, absent
intensive manipulations, in Virginia are in the James River. The
native oyster populations in the James River occupy natural hard
substrate bottom habitats with multiple reefs (> 20) occuring
over a gradient of salinity conditions so as to consitute natural
replicates throughout the range of available salinities. The extant
James River oyster populations have been intensively monitored
by the Virginia Institute of Marine Science Molluscan Ecology
program in collaboration with the Virginia Marine Resources Commission
Division of Shellfish Conservation and Replenishment through fishery
independent surveys. From 1993 through the present, both spatial
and temporal variability within replicate oyster populations have
been examined against a background of shifting environmental (temperature,
salinity, water flow) and disease conditions. These fishery independent
data sets provide the opportunity to describe the James River
oyster populations as "stable" or self sustaining using metrics
of either oyster density (abundance per square meter) or demographics
as indicated by biomass (g tissue dry weight). Either of these
metrics is suitable as a starting point to estimate population
reproductive output (as either gametes or embryos), fecundity
(embryo or egg density) and ultimately, veligers on a reef by
reef basis along the natural salinity gradient. These reef specific
data sets for natural populations provide tools to identify and
understand location specific variation within a single habitat
related to environmental conditions. These natural spatial variations
within James River oyster populations span orders of magnitude
and provide comparative barometers to estimate realisitic restoration
goals across a broad spatial scales.
The ultimate
goal of a native oyster restoration effort within an estuary is
to create a native oyster population with sufficient spatial coverage
and ecological influence within the estuary so as to be self-sustaining.
Unless all parts of the restoration effort (shell plants, reefs,
planted broodstock) function properly and contribute, the restoration
effort will not be successful. Mimicry of existing naturally self
sustaining native oyster populations in the James River at similar
temperature, salinity, and disease conditions is an appropriate
restoration target. For comparative purposes, sites within the
James River populations with temperature, salinity, and disease
conditions similar to the restoration site of interest should
be used as the barometer for restoration success. Within a data
type (oyster density, biomass, fecundity), data from the restoration
site of interest will be compared to the five year mean of the
same data type from James River reefs at the same environmental
conditions. These comparisions are ecologically and biologically
relevant and will provide conservative barometers to realistically
evaluate the progress of a restoration project towards the ultimate
goal of a self sustaining oyster population.
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