Mapping & Surveying: Monitoring the Active Replenishment of Subsiding Habitat Project (MARSH)
Some of the Pamunkey River marshes in
Virginia’s York River Watershed have been undergoing
changes in plant community composition for
at least the last decade. The taller grasses such as
Big Cordgrass, Spartina
cynosuroides, have been replaced
by the lower elevation
plant Arrow Arum (Peltrandra virginica), and, in some cases, by
mudflats.
It is thought that the observed
changes are a result of
rising sea level, potentially
combined with local subsidence,
making it impossible for the
marshes to accumulate surface
material fast enough to precisely
maintain their position in the
intertidal zone. This would explain the transition
from a plant community dominated by Big
Cordgrass to one dominated by Arrow Arum.
Researchers have three primary questions:
1. What would be the ecological significance of the
change in marsh character?;
2. Could anything be
done to maintain or restore the original plant
community structure?; and
3. Can a management
strategy be developed that will counter this change?
How can this be
done?
The resulting
project was
designed to
accomplish
several things:
1. Document the differences between Big
Cordgrass and Arrow Arum communities;
2. Evaluate several methods of raising the marsh
surface incrementally to keep pace with sea level
rise; and
3. Assess the potential
for unintented expansion of the
invasive Common Reed grass
(Phragmites australis).
Scientists at VIMS are
studying the effect of spray
dredging a thin layer of material on the marsh surface in three
locations. At the same time,
other smaller scale experiments
involving Koir logs and mesh
were installed to test sediment
trapping effectiveness.
What is being studied?
The types and abundances of plants were
sampled prior to the spray dredging operation. In
addition, the bottom dwelling animals were
sampled and the bottom contours were measured
in the area where the dredge was to operate prior
to spray dredging. Finally, detailed elevations were
taken in the proposed dredge spray areas. Water
quality monitors were established both prior and
after the dredging activity.
Other sampling
included bird
communities,
fish communities,
and insect
communities.
Project Sponsors
-
Mr. and Mrs. John Paul Causey
-
Mr. Edmund T. Dejarnette, Jr.
-
Elis Olsson Memorial Foundation
-
Mr. George C. Freeman
-
Mr. Bruce C. Gottwald, Sr.
-
Mr. Floyd D. Gottwald, Jr.
-
Mr. Herbert W. Jackson, IV
-
Ms. Martha J. Langford
-
The National Fish and Wildlife Foundation
-
Mr. F. Scott Reed, Jr.
-
The C.F. Sauer Company
-
Mr. Sidney B. Scott
-
Universal Leaf Foundation
-
Mr. Coleman Wortham, III
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