Page 137 - Environment: The Science Behind the Stories

ThE SCIENCE BEhIND ThE STOry

“Turning the Tide”

for Native Oysters
in Chesapeake Bay Washington, D.C.

In 2001, the Eastern oyster (Crassostrea MARYLAND
virginica) was in dire trouble in the
Chesapeake Bay. Populations had
dropped by 99%, and the Chesapeake’s P o t o m a c R i v e r
oyster industry, once the largest in the
world, had collapsed. Poor water qual- VIRGINIA
ity, reef destruction, virulent diseases Chesapeake
spread by transplanted oysters, and Bay
200 years of overharvesting all contrib- Experiment
conducted in the
uted to the collapse. Great Wicomico River
Restoration efforts had largely Miles 25
failed. Moreover, when scientists or
resource managers proposed to rebuild david Schulte, u.S. army corps of Figure 1 Schulte’s study was conducted
oyster populations by significantly engineers in the great Wicomico river in Virginia in
restricting oyster harvests or establish- the lower chesapeake bay.
ing oyster reef “sanctuaries,” these densities, clarifies waters, and supports
initiatives were typically defeated by the the growth of underwater grasses that
politically powerful oyster industry. All provide food and refuge for waterfowl hard as stone. Throughout the bay,
this had occurred in a place whose very and young crabs. Because introduc- massive reefs that at one time had
name (derived from the Algonquin word tions of invasive species can have jutted out of the water at low tide had
Chesepiook) means “great shellfish profound ecological impacts been reduced to rubble on the bottom
bay”. (pp. 106–107), the Army Corps of from a century of repeated scouring
With the collapse of the native Engineers was directed to coordinate by metal dredgers used by oyster har-
oyster fishery and with political obsta- an environmental impact statement vesting ships. The key, Schulte real-
cles blocking restoration projects for (EIS, p. 192) on oyster restoration ized, was to construct artificial reefs
native oysters, support grew among approaches in the Chesapeake. like those that once existed, to get
the oyster industry, state resource It was in this politically charged, oysters off the bottom—away from
managers, and some scientists for high-stakes environment that Dave smothering sediments and hypoxic
the introduction of Suminoe oysters Schulte, a scientist with the Corps waters—and up into the plankton-rich
(Crassostrea ariakensis) from Asia. and doctoral student at the College of upper waters.
This species seemed well suited for William and Mary, set out to determine Armed with the resources avail-
conditions in the bay and showed whether there was a viable approach able to the Corps, he opted to take
resistance to the parasitic diseases to restoring native oyster populations. a landscape ecology approach and
that were ravaging native oysters. The work he and his team began restore patches of reef habitat on nine
Proponents argued that introducing would help turn the tide in favor of complexes of reefs covering a total of
Suminoe oysters would reestablish native oysters in the bay’s restoration 35.3 hectares (87 acres) in an oyster
thriving oyster populations in the bay efforts. sanctuary near the mouth of the Great
and revitalize the oyster fishery. One of the biggest impacts Wicomico River (Figure 1) in the lower
Introducing oysters would also on native oysters was the destruc- Chesapeake Bay. This approach was
improve the bay’s water quality, propo- tion of oyster reefs by a century of very different from the smaller-scale res-
nents said, because as oysters feed, intensive oyster harvesting. Oysters toration efforts of the past.
they filter phytoplankton and sedi- settle and grow best on the shells of Artificial reefs of two heights were
ments from the water column. other oysters, and over long periods constructed in 2004 (Figure 2), and
Filter-feeding by oysters is an this process forms reefs (underwater oysters were allowed to colonize the
important ecological service in the outcrops of living oysters and oyster reefs, safe from harvesting. Oyster
bay because it reduces phytoplankton shells) that solidify and become as populations on the constructed reefs

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