DNR Using Innovative Bay Grass Restoration Techniques
Large-Scale Harvesting of Eelgrass Seeds Essential to Restoring Bay Grasses
ANNAPOLIS, MD — The Maryland Department of Natural Resources (DNR) Resource Assessment Service recently used a mechanical harvesting boat as an innovative approach to efficiently collect large amounts of eelgrass seeds to support large-scale bay grass restoration. Harvesting will continue through Friday, June 4 in Tangier Sound.
DNR biologists estimate they will harvest 20 million eelgrass seeds this year using this new technique; last year only 500,000 were collected. If 20 million seeds are successfully collected, 100 acres of eel grass could be restored.
Existing methods of collecting eelgrass seeds by hand cannot provide the number of seeds needed to support DNR’s restoration goals. This new method uses a boat to “mow” the grass beds, taking seeds and reproductive shoots but leaving the roots and rest of the plants in place. Only a small portion of the seeds and reproductive shoots will be removed from each healthy bed, and these will be planted later this year in unvegetated areas.
Bay grass acreage contracted in 2003 more than 30 percent in the entire Chesapeake Bay and 41 percent in Maryland’s portion. These facts underscore that it is vital to explore new methods for restoring bay grasses. Eelgrass harvesting is one of many actions that DNR is taking.
Bay grasses (also known as submerged aquatic vegetation, or SAV) are critical to a healthy Chesapeake Bay. They provide important habitats for young fish and crabs, serve as food for waterfowl, help protect shorelines from erosion, help keep water clear, consume excess nutrients, and add oxygen to the water.
Excessive nutrients (mainly nitrogen and phosphorus) and sediment resulting from human activities cloud the water and harm bay grasses by preventing sufficient sunlight from reaching the plants. Bay grass acreage in Maryland in 2003 was 30,990 acres, which is only 28 percent of Maryland’s 110,000-acre goal for 2010.
Reducing the amount of nutrients and sediment in Chesapeake Bay is the single most important action we can take to restore bay grasses. DNR is working on numerous fronts to accomplish this. Planting or seeding bay grasses on a large scale in strategic locations will help achieve the state’s restoration goal.
DNR has long recognized the need for a large-scale restoration approach. There are areas of the Bay where water quality has improved sufficiently to support bay grasses, yet restorative plantings could not take place for lack of seeds. Planting or seeding large beds could possibly lead to vigorous natural revegetation in adjoining areas. Maryland and Virginia have collectively set a goal of planting or seeding 1,000 acres by 2008.
In 2003, Maryland began experimenting with large-scale eelgrass (a high-salinity species of bay grass) restoration projects in the Patuxent and Potomac Rivers. Virginia conducted similar experiments on the Piankatank River. Approximately five acres were seeded in Maryland. The primary lesson learned was that existing methods of collecting eelgrass seeds by hand are simply inadequate for large-scale restoration.
DNR and the Virginia Institute of Marine Sciences (VIMS) are collaborating this year on innovative techniques that could result in the restoration of 100 or more acres (20 times the acres seeded in 2003) of eelgrass in Maryland.
In May and June 2004, a mechanical harvesting boat will harvest large amounts of eelgrass reproductive shoots from healthy beds in Tangier Sound. After the beds are “mown,” the eelgrass shoots and seeds will be taken to DNR’s Piney Point Aquaculture Facility on the Potomac River. In the following months, they will be processed to separate the seeds from the shoots. In the fall of 2004, the seeds will then be planted in the Potomac and Patuxent Rivers using a variety of methods.
DNR and VIMS 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 method for future large-scale restoration.
Posted June 3, 2004