Virginia Coastal Program: 2003 Coastal Grant Project Description and Final Summary
Project Task:
FY2003 Task 12.04
Grantee:
Virginia Institute of Marine Science
Project Title:
Seaside Heritage Program: Restoration of Seagrasses on the Seaside of Virginia's Eastern Shore
Project Description as Proposed:
Seagrasses, primarily
eelgrass, Zostera marina, were once very abundant on Virginia’s
seaside, covering most of the subaqueous bottom. In the 1930s eelgrass
underwent a massive decline attributed to a wasting disease pathogen,
Labyrinthula sp. The decline was pandemic, affecting not only populations
on Virginia’s seaside but also populations on both sides of
the Atlantic. In August 1933, this region was affected by one of
the most destructive hurricanes to influence the area in the twentieth
century, contributing to the decimation of seagrasses in the bays.
Natural recovery of seagrasses since that time has been limited
primarily to Chincoteague, Sinepuxent, Isle of Wight and Assawoman
bays with no recovery in the Virginia seaside bays south of Chincoteague
Bay. VIMS ongoing eelgrass seed ecology research has pointed to
limited propagule supply as the most likely reason for no eelgrass
recovery here. Today, the Virginia seaside bays are primarily salt
marsh and macroalgal dominated, although recent efforts at restoring
eelgrass in the seaside bays have had remarkable success since 1999.
The projected objectives for year 2 of the SHP builds upon restoration
success of previous years and will continue the large scale efforts
at locations deemed suitable for further seed enhancements as well
as pinpointing additional sites for further expansion in the following
years. The program in Year 2 has seven tasks, mirroring much of
what has been done in Year 1:
1. MONITOR SUCCESS OF TEST AND ESTABLISHED SEAGRASS AREAS
The most critical aspect of this project is to monitor both the
established seagrass areas planted since 1998 as well as the small
test plots in the Hogg Island Bay (Task 6) area to ensure that conditions
are being maintained that are suitable for seagrass growth and that
new areas are now suitable for larger scale restoration efforts.
Test plots planted at Hog Island Bay will be assessed for survivorship
at one, six, nine and twelve month intervals. If after 12 months,
plants are still present in the test plots, efforts will be targeted
to larger scale efforts similar to what has occurred in South Bay,
Cobb Bay and the Gull Marsh area. Seagrass plots planted between
1998 and 2003 will be monitored with a combination of on-site field
checks but also low level remote sensing techniques. Aerial photographs
will be taken of previously restored sites, ortho-rectified and
given cover percentages based on an objective classification of
cover.
2. CONTINUE TO REFINE THE METHODOLOGY FOR PASSIVELY COLLECTING SEEDS
Our protocol for collecting seeds requires the harvesting of mature
flowering shoots with ripe seeds by hand during a three-week window
in late May. Divers, using either snorkeling or SCUBA, pull flowering
shoots from established beds and place them in mesh bags. This method
is effective but optimal collection methods require diving or snorkeling.
In recent years we have observed seeds floating at the air-water
interface, a result of seeds being released from the plant with
a bubble allowing it to float to the surface and then being transported
by wind. We observed seeds collecting against debris suggesting
that there may be a way of passively collecting these floating seeds.
We found we could actively collect these floating seeds by passing
a fine mesh dip net through the water but this process collects
seeds from a small area and may not be as effective as harvesting
mature shoots with seeds.
In spring 2003, we tested two methods of passively collecting seeds
that we developed during the winter 2003. One method involved deployment
of a small net raised at the surface with floats that allowed floating
seeds to be retained by a fine mesh net. The second method was a
fine meshed fish seine. The seine was not effective the large surface
area of the net was ineffective in the currents at the site and
as seeds rolled down the seine and out of the bottom. The raised
net did passively collect seeds but was quite susceptible to strong
winds. We will develop a second-generation collector and test that
in the spring of 2004. We will not use the seine as few seeds were
collected in the initial trials.
3. COLLECT SEEDS FOR 2004 RESTORATION EFFORTS
Our previous work with harvesting seeds has shown that there is
generally a 3-4 week window to harvest mature reproductive shoots
with ripe seeds, usually from the first week of May to the first
of June. As our observations have indicated that floating seeds
are available for a much briefer period (perhaps a week at most),
our major efforts will be to continue our previous protocols of
hand harvesting reproductive shoots with mature seeds when they
become available until the time when our observations indicate that
most seeds have been released by the plants. Our past efforts have
usually been completed by June 1. Harvested reproductive shoots
are returned to the VIMS laboratory and placed in large seawater
holding tanks at the SAV greenhouse. These are monitored for seed
release and when completed, seeds are separated from all detritus
and plant material and held until the period when seeds are broadcast.
Our goal for seed collection efforts in 2004 will be 5 million seeds
(previous efforts in 2001, 2002 and 2003 yielded 6.6, 2.4 and 2.6
million seeds, respectively). The total number of seeds harvested
will be a function of weather conditions that influence how many
days flowering shoots can be harvested and the total number of seeds
produced by the plant.
4. COLLECT WATER QUALITY WITH DATAFLOW IN AREAS WITH EXISTING EELGRASS
AND ADJACENT UNVEGETATED AREAS.
Our previous developmental work in several Chesapeake Bay tributaries
has allowed us to map water quality over large shallow water areas
using Dataflow techniques. Discreet measurements are taken at 2-3
second intervals as water is passed through a flow-through measuring
chamber while the vessel is traversing the study area. Concurrent
with the sensor measurements (including turbidity, chlorophyll fluorescence,
temperature, salinity, pH, dissolved oxygen) GPS and depth information
are recorded. This information is then analyzed using GIS techniques
and data layers of water quality constituents can be quantified
and displayed for the vessel path or interpolated for the entire
study area. Fixed stations using similar sensor arrays are deployed
for two week or longer intervals so that this high frequency spatial
record can be integrated with the high frequency temporal record
for the region. Preliminary runs in this region using DataFlow in
the late summer of 2002 and ongoing work in 2003 have demonstrated
marked changes in water quality across the South Bay restoration
area. During 2004 our goal for this task will be to conduct Dataflow
cruises at monthly intervals throughout the SAV growing season and
to deploy the fixed stations for a minimum of 14-day intervals bi-monthly
throughout this same period. This effort will be in the areas of
the new test plots.
5. LARGE SCALE SEAGRASS RESTORATION
Our previous work in the seaside bays between 1999 and 2003 has
shown that broadcasting eelgrass seeds has proven to be a very effective
technique for restoring eelgrass on larger scales than a few square
meters. In 1999 and 2000, experiments were conducted in small plots
of 4 and 100 m2 with seed densities ranging from 2.5 to1250 seeds
m-2. In 2001, we broadcast approximately 4.4 million seeds into
36 one-acre plots in South, Cobb and Magothy bays at two seed densities
100,000 and 200,000 per acre (25 and 50 seeds m-2, respectively).
Because of the fewer number of seeds collected in 2002, we broadcast
seeds to 24 one acre plots at two seed densities: 50,000 seeds (12.5
seeds m-2) in 12 acres and 100,000 seeds (25 seeds m-2) in 12 acres.
In the fall, 2003, we broadcast seeds in a new pattern to reflect
the additional knowledge we have gained from the last few years
of seed broadcasting in South Bay. We have observed some seed plots
expanding in a direction that may have been influenced by wind and
wave action moving floating seeds. The design we chose for 2003
allowed us to test this hypothesis. We broadcast seeds into 0.5
acre circular plots with seeds placed either in a 1-2 meter ring
(the circumference) or in the entire circle. We broadcast seeds
into 37, 0.5 acre rings (12 filled circles and 25 rings). The design
will allow us to assess how rapidly plants spread from a specific
areal extent and the direction of spread will allow us to determine
the influence of tides and wind. The total number of acres where
seeds will be broadcast in 2004 will be a function of how many seeds
are harvested in 2004, and a specific design chosen based on our
continuing analysis of how previously planted plots are spreading.
Plots will be concentrated in the Gull Marsh/Hogg Island Bay area
where new test plots were planted in fall, 2003. Actual number of
acres planted will depend on the final seed count.
6. ESTABLISHMENT OF TEST PLOTS FOR ADDITIONAL LARGE SCALE EFFORTS
While we have been having notable success with seagrass transplants
in South Bay since 1998, and most recently, seed and adult plots
in the south end of Cobb Island Bay and around the Gull Marsh area,
we plan to expand the efforts of seagrass restoration to more northern
sections of the coastal bays. However, our transplant protocols
call for small test plots to be placed at sites where no plantings
have been conducted previously to ascertain suitable growing conditions
before larger scale efforts are initiated. We propose to place small
(4 m2) test plots of both adult plants in areas north of the current
test plots at Gull Marsh in the fall, 2004, to ascertain whether
conditions in this region are suitable for seagrass growth. Placement
of adult plots will follow protocols used in VIMS previous work
(Orth, et al., 1999).
7. PHOTOMOSAICING AND MAPPING OF SEAGRASS FROM AERIAL PHOTOGRAPHS
Scanned aerial photographs of the seaside bays taken during 2003
will be georectified and orthographically corrected to produce a
seamless series of aerial mosaics following the standard operating
procedures used by the annual SAV monitoring program. ERDAS Orthobase
image processing software will be used to orthographically correct
the individual flight lines using a bundle block solution. Camera
lens calibration data will be matched to the image location of fiducial
points to define the interior camera model. Control points from
USGS DOQQ images will provide the exterior control, which is enhanced
by a large number of image-matching tie points produced automatically
by the software. The exterior and interior models are combined with
a 30-meter resolution digital elevation model (DEM) from the USGS
National Elevation Dataset (NED) to produce an orthophoto for each
aerial photograph. The orthophotographs that cover each USGS 7.5
minute quadrangle area are then adjusted to approximately uniform
brightness and contrast and will be mosaiced together using the
ERDAS Imagine mosaic tool to produce a one-meter resolution quad-sized
mosaic. Mapping of seagrass will follow protocols developed for
SAV populations in Chesapeake Bay.
Federal Funding:
$85,000
Project Contact:
Robert J. Orth, 804/ 684-7392 -jjorth@vims.edu
Project Status:
Grant Closed
Final Product Received:
Project Summary Provided by Grantee:
Seagrasses, primarily eelgrass, Zostera marina, were once very abundant in the coastal bays, covering most of the subaqueous bottom. In the 1930s eelgrass underwent a massive decline attributed to a wasting disease pathogen, Labyrinthula sp. And along with a massive hurricane in 1933, seagrasses were totally eliminated from these bays. With initial work at attempts in restoring seagrass starting in 1996 being highly successful the goal of the work proposed here is to continue the restoration of seagrasses in the seaside coastal bays. The second of the three year project had 6 tasks: 1) monitor success of test and established seagrass areas which showed most areas planted in previous years have continued to grow and spread, 2) collect seeds for 2004 efforts - 7.1 million seeds were used for restoration efforts in Spider Crab and South bays, 4) surface mapping of water quality with dataflow-four cruises were completed during the 2004 field season between April 21 and Oct 29 collecting data on turbidity, chlorophyll fluorescence, temperature, salinity, pH, dissolved oxygen. Four deployments were completed using the fixed station in May, July, and October. 4) large scale seagrass restoration - we planted 7.1 million seeds (both spring and fall plantings in 2004) in approx. 37 acres at seed densities of 150,000 to 300,000 per acre, with 5 acres planted in South Bay and the remaining in Spider Crab Bay, 5) establishment of test plots in the Hog Island Bay area - test plots were planted at nine new locations in the fall, 2004, and 6) Aerial photographs - low level color and high level black and white images were collected in late fall, 2004. The results to date have important implications in seagrass restoration projects esp. in the use of seeds versus whole plants and monitoring water quality to insure that we understand any alterations that may occur in this system to the restoration efforts. In addition, a supplemental grant allowed for additional signage to be placed in the Chincoteague Bay SAV sanctuary.
Form C end
Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email: Laura.McKay@deq.virginia.gov
A more detailed Scope of Work for this project is available. Please direct your request for a copy to Virginia.Witmer@deq.virginia.gov
