DNR Continues Bay Grass Restoration Efforts with Eelgrass Seed Collection in Tangier Sound

June 13, 2005 - The Department of Natural Resources (DNR) Resource Assessment Service recently completed a third season of eelgrass seed collection in Tangier Sound near Crisfield, MD using a mechanical harvesting boat introduced in 2004.

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. The same mechanical harvester was used again this year, and with increased efforts roughly 30 million eelgrass seeds were harvested from Tangier Sound from May 23 – June 9.

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, 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. While the Chesapeake Bay Program annual bay grass survey indicates a 14 percent increase to about 73,000 acres in 2004 this is well short of the 2010 goal of 185,000 acres.
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. In addition, DNR is continuing efforts to plant or seed bay grasses on a large scale in strategic locations to help achieve the state’s restoration goals.

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 a lack of seeds prevents recolonization of these areas. Planting or seeding large beds with 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. Virginia conducted similar experiments on the Piankatank River. In 2003, approximately five acres were seeded in Maryland. Increased collection efforts in 2004 resulted in a total of 36.25 acres being seeded at four sites on the Patuxent River and three sites on the Potomac River.

Using the mechanical harvesting boat, DNR biologists collected eelgrass reproductive material from Tangier Sound from May 23rd until June 9th. The harvester “trims” the grass beds, removing seeds while leaving the roots and rest of the grasses intact. Only a small portion of the seeds are removed from each healthy bed allowing them to reproduce and persist at healthy levels.
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. Over 600 seed bags were deployed on the Potomac River and 240 on the Little Choptank River during the past three weeks.

The remainder of harvested seed material has been transported by commercial watermen 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. Seeds will then be planted this fall in Maryland on the Potomac, Patuxent, and Little Choptank Rivers and in Virginia on the Piankatank River.

DNR and the Virginia Marine Institute of Science 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. 
For more information on large scale bay grass restoration, contact Mike Naylor at the Department of Natural Resources (410)260-8630 or mnaylor@dnr.state.md.us.