Seagrass Restoration

The decline of eelgrass in Chesapeake Bay, especially since the mid-1970s, has generated interest in restoring this valuable habitat. In 1978, VIMS researchers began investigating techniques for reintroducing eelgrass to areas where it had been eliminated. Here we highlight the success of our efforts to restore eelgrass to VIrginia's seaside bays, and a related effort to reintroduce bay scallops to those restored eelgrass meadows.

Seaside Bays

VIMS professor Robert “JJ” Orth began sowing South Bay, Spider Crab Bay, and Hog Island Bay with eelgrass seeds in 1999. Barren at the time, these bays are now home to more than 6,000 acres of lush eelgrass meadow, making them the largest and most successful example of seagrass restoration in the world. Current work focuses on extensive plantings in Spider Crab Bay and smaller, exploratory plantings around the lower western shore of Chesapeake Bay. VIMS work in the Virgnia Coastal Bays was highlighted in a 2012 special issue of Marine Ecology Progress Series.

Bay Scallops

The dramatic success of eelgrass restoration in South Bay has presented the opportunity to re-introduce bay scallops—a once-abundant and commercially valuable member of the area's coastal marine ecosystem. Working with VIMS' Eastern Shore Lab, we are initiating a study of the growth and mortality of juvenile scallops deployed in the restored seagrass bed in South Bay. Learn more.

International

VIMS professor Robert “JJ” Orth has been called the "Johnny Appleseed" of seagrass. VIMS' success in restoring eelgrass to the cool, clear waters of Virginia's seaside bays has led to collaborations with restoration scientists and resource managers in both northern Europe and Australia.

Chesapeake Bay

Efforts to restore eelgrass in Chesapeake Bay by transplanting have failed to significantly increase its overall abundance in most locations. Early success in restoring eelgrass to the lower York and James rivers via seed has also not persisted in the long run. Poor water quality and increasing water temperatures are likely responsible. Current Bay restoratoin efforts focus on the Poquoson Flats.

Opportunity & Challenges

Success with Seeds

VIMS researchers helped pioneer the tools and techniques used to gather, preserve, and deploy shoots and seeds for restoring seagrass not only in Virginia but worldwide. Their work has shown that using eelgrass seeds can be much more efficient and effective than transplanting adult plants for large-scale restoration in the mid-Atlantic.

Taking the Next Step

Despite the success of eelgrass seeding efforts, many young seedlings fail to develop into adult plants, and recent evidence suggests that waves and currents remove many young seedlings before they become established. Current experimental work thus focuses on:

Understanding how different physical factors influence seedling establishment at different restoration sites
Investigating the potential importance of high-density, repeated seeding at promising restoration sites

Tools & Techniques

Transplanting Eelgrass Using Shoots

Orth, R. J., M. C. Harwell, et al. 1999. A rapid and simple method for transplanting eelgrass using single, unanchored shoots. Aquatic Botany 64(1): 77-85.
—In a large-scale eelgrass restoration program that began in 1996 in Chesapeake Bay, we developed a simple manual technique to transplant single, unanchored shoots with rhizomes into the sediment at an angle to a depth between 25 and 50 mm, allowing the more compact area of the sediment above the rhizome to assist in anchoring the plant.

A review of techniques using adult plants and seeds to transplant eelgrass (Zostera marina L.) in Chesapeake Bay and the Virginia Coastal Bays. pp. 1-17. In: S. F. Treat and R. R. Lewis. (eds.). Proc. Conf. Seagrass Restoration: Success, Failure, and the Costs of Both. March 11, 2003. Sarasota, Florida. 175pp.
—Highlighted the importance of transplant timing, use of fertilizer, labor requirements, and initial success of various transplant techniques.

Mechanized and Manual Transplanting of Eelgrass

Fishman, J. R., R. J. Orth, et al. 2004. A comparative test of mechanized and manual transplanting of eelgrass, Zostera marina, in Chesapeake Bay. Restoration Ecology 12(2): 214-219.
—The laborious process of manually transplanting seagrass has often limited the size of restoration efforts. This study tested the efficiency of a mechanized planting boat, previously used for transplanting Halodule wrightii, relative to manual transplanting methods for establishing eelgrass in Chesapeake Bay.

Mechanical Seed Planter for Transplanting Eelgrass

Orth, R. J., S. R. Marion, et al. 2009. Evaluation of a mechanical seed planter for transplanting Zostera marina (eelgrass) seeds. Aquatic Botany 90(2): 204-208. Doi 10.1016/J.Aquabot.2008.07.004

Restoring eelgrass (Zostera marina) from seed: A comparison of planting methods for large scale projects. 2008. SAV Technical Notes Collection (ERDC/TN SAV-87-1). Vicksburg, MS: U.S. Army Engineer Research and Development Center.
—Few seagrass transplant projects have relied on seeds, and those projects using eelgrass seeds have generally found low rates of seedling establishment (<10%). We compared seedling establishment achieved by a mechanical seed planter with seeds broadcast on the sediment surface by hand. Researchers: Robert Orth, Scott Marion, Steve Granger, Mike Traber.

Innovative Techniques for Large Scale Seed Based Eelgrass Restoration

Marion, S. R. and R. J. Orth 2010. Innovative Techniques for Large-scale Seagrass Restoration Using Zostera marina (eelgrass) Seeds. Restoration Ecology 18(4): 514-526. Doi 10.1111/J.1526-100x.2010.00692.X

Innovative techniques for large-scale collection, processing, and storage of eelgrass (Zostera marina) seeds. 2007. SAV Technical Notes Collection (ERDC/TN SAV-07-2). Vicksburg, MS: U.S. Army Engineer Research and Development Center.
—Eelgrass restoration using seeds is increasingly recognized as a viable option for both small- and large-scale projects. The purpose of this research was to develop methodologies for achieving the full potential for large-scale restoration presented by mechanized eelgrass seed harvesting. The specific goal was to develop techniques and infrastructure to fully exploit potential mechanized seed-harvesting capabilities, and to identify optimal conditions for storage and survival of large volumes of harvested seeds.

Lessons Learned

Water Quality is Key

Improving water quality is key to restoring seagrass coverage. The establishment of water-clarity goals to reduce sediment and nutrient inputs from upland sources, tidal shorelines, tidal resuspension, and estuarine processes will facilitate seagrass restoration and recovery.

Seagrass Health Starts on Land

Land-use planning, wetland protection, and planting of riparian buffers can help restore and protect seagrasses.

It Pays to Start Small

Where water quality is good enough to support seagrass survival, hands-on restoration efforts can help establish, expand, or diversify grass communities. Small test plantings can help evaluate whether conditions at a particular location can support seagrass. If test plantings are successful at a site, larger-scale restoration may accelerate seagrass recovery.

Grass Begets Grass

Initial results suggest that efforts to improve water quality and restore and protect seagrass may start an "ecological chain reaction" in which clearer, cleaner water promotes grass growth, which further improves water quality for expansion of even more seagrass.