Large Scale Bay Grass Restoration
with Eelgrass Seed Collection
There are areas of the
Bay where water quality has improved sufficiently to support bay grasses, yet a
lack of seeds prevents recolonization of these areas. Establishing large beds
using seeds collected from healthy beds elsewhere could lead to vigorous natural
revegetation in adjoining areas. In 2003, Maryland began experimenting with
large-scale eelgrass (a high-salinity species of bay grass) restoration projects
in the Patuxent and Potomac Rivers. In 2003, approximately five acres were
seeded in Maryland. Increased collection efforts in 2004 and 2005 resulted in a
total of 63 acres being seeded at four sites on the Patuxent River and four
sites on the Potomac River.
In early July the
Department of Natural Resources (DNR) Resource Assessment Service completed a
fourth season of eelgrass seed collection in Tangier Sound near Crisfield, MD
using a combination of manual and some mechanical collection methods.
During 2003, the first year of eelgrass seed collection, 500,000 seeds were
collected manually. However, collection of seed material by hand was not
sufficient to meet DNR’s restoration goals of 1000 acres of bay grass by 2008.
The introduction of a mechanical harvesting boat dramatically increased the
number of seeds collected to about 17 million in 2004 and 30 million in 2005.
In 2006, eelgrass reproductive shoots were roughly half the length the normal
length. The probably cause for this size reduction is the elevated July and
August 2005 water temperatures (2-30F above normal) and the resulting thermal
stress. Because of the reduced size, collecting reproductive material in large
amounts using the mechanical harvester was not possible. Biologists resorted to
manual collection using SCUBA, a less efficient process yielding less total
reproductive material. The 2006 eelgrass harvest season resulted in only 81 bags
of material collected in the field- far less than the nearly 2000 bags collected
Some of the harvested material was used to make seed bags for immediate
distribution simulating natural seed dispersal. Mesh bags were stuffed with
freshly cut seed material and deployed allowing for seeds to mature and settle
to the bottom in suitable restoration areas. Seed bags were deployed on the
Potomac and Patuxent Rivers in early June.
The remainder of harvested seed material has been transported to DNR’s Piney
Point Aquaculture Facility where it will be held through the summer in large
tanks to allow for seeds to separate from non-seed material. These seeds will
then be planted this fall on the Potomac and Patuxent Rivers.
DNR and will closely monitor both the effect, if any, on the health of the
eelgrass beds from which the seeds are taken as well as the relative success of
the different seeding techniques, the goal being to identify the most
cost-effective large-scale restoration method to employ to meet the Chesapeake
Bay restoration goals.
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