Shortage of eelgrass a slippery problem
Before disease decimated it years ago, eelgrass thrived around the globe in estuaries like Delaware’s Inland Bays. The sea-dwelling plant provides food and habitat for crabs, fish and waterfowl. It improves water quality by removing excess nutrients from the water and stabilizes the bay bottom as its long, ribbon-like leaves trap floating particles of sediment.
Environmental managers would like to get their hands on more eelgrass for bay restoration projects. But, it’s not as easy as going out and buying a bag of grass seed or a flat of plants at the local garden center. At least not yet.
In their laboratory at the College of Marine and Earth Studies in Lewes, Del., marine botanists Jack Gallagher and Denise Seliskar, who also co-direct UD’s Halophyte Biotechnology Center (see sidebar on next page), and graduate student Kayti Tigani are working to develop techniques for propagating eelgrass, known scientifically as Zostera marina.
The scientists recently were awarded a $198,429 grant from the Cooperative Institute for Coastal and Estuarine Environmental Technology to conduct the research. The institute develops tools for clean water and healthy coasts nationwide.
“Eelgrass is a cold-water plant that was once widely distributed,” Gallagher says. “Then, in the 1930s, there was a worldwide die-off of the plant due to wasting disease,” thought to be caused by a slime mold that attacks the leaves. The plant’s range in the United States is from North Carolina to Maine on the East Coast and from northern California to Alaska on the West Coast.
The loss of the once-prolific eelgrass set off a chain reaction of serious impacts, including the starvation of large numbers of brant, a species of waterfowl that relies on the plant as a primary food source.
While eelgrass populations have rebounded in some locations over the years, restoration efforts have been essential to the plant’s recovery elsewhere, particularly in areas that have undergone significant environmental degradation due to increased nutrient inputs, erosion and other stresses, Gallagher says. However, the restoration process often is slow due to the scarcity of plant material.
Currently, environmental managers must harvest seeds from eelgrass growing in the wild or dig up plants from healthy beds for transplant. In some U.S. states, eelgrass has been made available for restoration projects only through the good will and cooperation of neighbors. Delaware, for example, has obtained plants from Maryland’s coastal bays and off Long Island, N.Y., to help re-establish eelgrass beds in Indian River Bay—one of the state’s Inland Bays.
“Eelgrass is precious everywhere,” Seliskar says. “Understandably, people who have the plant growing in their waters may be reluctant to part with it because they need what they’ve got to sustain their own grass beds.”
The UD research team is working on two methods for propagating eelgrass. One focuses on developing micropropagation and proliferation techniques using tissue cultures of eelgrass native to a specific area. This approach would enable the scientists to grow large numbers of new shoots from a single plant. The offspring would closely resemble the parent plant.
One of the biggest hurdles the scientists face with this technique is keeping the eelgrass growing in culture in a sterile laboratory for more than a year—a feat they recently accomplished.
“These things are hard to propagate, and we don’t really know why,” Gallagher says. “Bacterial contamination has been the downfall of a lot of efforts. Figuring out the right growth media is critical. Then again, it may be that the plants don’t want to be in a sterile situation. In the natural environment, this plant would have a lot of microorganisms associated with it.”
If the scientists can get the technique to work, he says, thousands of eelgrass plants generated from a single plant could be maintained in test tubes in a refrigerator, waiting for deployment to the field when needed.
“Then, if there’s an activity such as an oil spill or some potential for a problem, you would have ready access to a ‘seed bank’ of eelgrass from your local area for restoration efforts,” Gallagher says.
In the second propagation technique, the scientists will take a small amount of eelgrass tissue to generate callus, undifferentiated plant material that looks something like cauliflower. From this material, small grasses with many different genetic traits can be produced. The UD scientists have used this technique successfully with several species of marsh plants and now want to try it with eelgrass.
“One advantage of this technique is that it might yield a plant that would thrive where it can’t grow now due to environmental changes,” Gallagher says. “For example, you might discover an eelgrass plant that would survive on a different bottom sediment from the sandy one it’s used to, such as the silty clay generated from erosion.”
In addition to eelgrass, the scientists will test their techniques on a warm-water seagrass called turtle grass (Thalassia testudinum) in hopes of developing a propagation protocol for it, too. That plant, which grows on sand and coral sea bottoms, is the most common seagrass in the Caribbean.
Several National Estuarine Research Reserve sites along the U.S. coast are collaborating with the University researchers and providing access to seagrass growing in their locations.
This spring, Kayti Tigani, who is working on her master’s degree in marine biology-biochemistry with Gallagher as her adviser, will visit reserves in New Hampshire, Rhode Island, North Carolina, Florida, Oregon and California to collect seagrass seeds and plants for the research.
After earning her bachelor’s degree in botany, where her focus was on terrestrial plants, Tigani sought out Gallagher and Seliskar to explore marine plants, particularly the tissue culture of seagrass, for her master’s degree program. She’s met the transition from land to sea plants with enthusiasm and now routinely dons snorkeling gear to check on Delaware’s eelgrass beds.
“I really am a fish at heart,” Tigani says. “My family is very involved in water sports, so I’m very comfortable in the water. I love my work, whether it’s in the field or in the laboratory. We have a great research team, and I feel so lucky to be here.”
The scientists also will collaborate with two industry partners in their quest to develop seagrass propagation techniques—Seagrass Recovery Inc., in Tampa, and Environmental Plant Resources Inc., in Bradenton, Fla. The latter company is owned by Otto Bundy, AG ’60M, who earned his master’s degree in horticulture.
“This research has a practical end to it and that appeals to me,” Gallagher says. “We’ve always been interested in projects that have a practical application.”