Project studying submerged aquatic vegetation in Back Bay shows promise, needs funding

Dr. Sara Sweeten is seen checks the progress of wild celery plants in southern Virginia Beach during a visit in June. [John-Henry Doucette/The Princess Anne Independent News]

VIRGINIA BEACH — A couple of years ago, Dr. Sara Sweeten, a research scientist at Virginia Tech, stumbled across specimens of an aquatic plant called wild celery that had been started from seeds left behind by undergraduate students who had been working on a project at the university in Blacksburg. 

Sweeten started “playing around” with the plants, which were grown from seeds that came from Back Bay in Virginia Beach, in part, because she didn’t want them to die.

“I just picked up the plants to see if I could get them to grow for fun,” she said.

That project got serious with a realization: “Wait a minute, I can grow this stuff.” 

There was an application for this plant that may provide a means for healthier watersheds, including here in Virginia Beach. 

Wild celery is a kind of submerged aquatic vegetation, an underwater grass comfortable in fresh water and, sometimes, brackish waters. There have been reductions of such plants over time here and elsewhere, and past studies of Back Bay have suggested a correlation between the loss of submerged aquatic vegetation and decreases in some wildlife, among other issues. Such grasses are also part of strengthening shorelines, which provides habitat and can contribute to protecting communities from floods.

According to the city’s strategy for adapting to sea level rise, submerged aquatic vegetation is one of the natural tools that helps fight flooding. 

The report defines such vegetation as “underwater grass beds” that, in high densities, “provide friction that slows down the flow of water and reduces the depth and duration of flood events.” Marsh restoration in the southern city is among the approaches of the plan. 

Submerged aquatic vegetation is part of the “green infrastructure” approach to protecting areas in and around the bay, which face a different kind of flooding than what is experienced elsewhere in the city. The southern watershed in Virginia Beach often experiences wind tide flooding, or flooding driven by winds that push water northward into the bay and into surrounding communities.

Wild celery [Sara Sweeten/Provided]
The city has made it clear that no approach will provide a magic fix to flooding woes, but the work by Sweeten, groups supporting the effort and individual backers and volunteers could be one piece of a much wider effort to address flooding and sea level rise.

Over time, Sweeten’s early efforts at Virginia Tech led a single growing table to expand to about 100 square feet of growing space, and then 350 square feet. The plants did not stay in the lab, though. In 2019, Sweeten, with the help of others, planted wild celery in locations that included spots in Virginia Beach’s Back Bay, such as the Princess Anne Wildlife Management Area and Back Bay National Wildlife Refuge.

Sweeten said she has also worked toward applying her technique of transplanting the grass in other communities, including preliminary work in Indiana and, soon, Ohio.

The plants that came to Virginia Beach were placed in mats surrounded by protective cages, and, except when a cage failed and plants were eaten, the plants survived and often thrived. 

“The problem with these plants is everything likes to eat them,” Sweeten said, “but the great thing about these plants is everything likes to eat them.”

That year, between May and October, the footprint of the plants increased. The results were encouraging enough to do it again. 

“Field tests of propagated plants in 2019 in the Back Bay watershed showed promising rates of survival, vegetative growth and fruit production,” according to the project summary, which reported 74 square feet of wild celery planted in the bay and other locations, including Claytor Lake in Dublin, Va., expanded to 767 square feet of coverage between May and October of that year.

And, the report said, “the plants produced over 600 seed pods, creating opportunities for natural reproduction.”

About 175 square feet were planted in seven sites around Back Bay this year, much of it with the help of volunteers and organizations supporting the effort, and in a wider range of locations. Those included a canal leading to the bay and on private property at the edge of the bay.

This past month, Sweeten was in town to check progress of the plants, and she said preliminary results are again promising. Not all sites were equal, but Sweeten on Thursday, Oct. 22, said there was progress.

She spoke during a town hall for the Princess Anne District hosted by City Councilmember Barbara Henley at the Virginia Beach Municipal Center. Henley, whose district includes southern Virginia Beach, an area with unique flooding challenges, introduced her.

“I think this research with wild celery in Back Bay is going to put her on the map,” Henley said.

Sweeten gave a brief presentation about the project, starting with the benefits of submerged aquatic vegetation as a habitat for wildlife and food source, including for waterfowl.

“It improves water quality by removing nutrients,” Sweeten said. “It holds down the substrate [layer below the plant] just like grass does on land. It keeps that from eroding. It sequesters as much carbon per acre as a tropical rainforest. 

“But really what’s important for Virginia Beach,” she continued, “is that SAV – and wild celery, in particular – decrease the frequency and severity of flooding. It slows down the water movement by creating friction, and it helps reduce the erosion of the shorelines.”

While stressing that the results this year are preliminary, Sweeten said some plants introduced in 2020 doubled their footprint and others expanded much more, in one case expanding from 21 square feet to 97 square feet. 

Overall, the 2020 plants grew from 175 square feet to 350 square feet in October, according to Sweeten.

Additionally, the 2019 plants had wintered and come back this year. They increased their footprint from about 50 square feet in May 2020 to 125 square feet in October.

One spot along the bay did exceptionally well among the 2020 group, even though it was in more challenging conditions than plants in more sheltered areas. 

“This is sort of surprising because it’s right here on the edge of the bay,” Sweeten said. “It’s taken all sorts of abuse. It’s had rough conditions.”

Sweeten said more study is needed to determine the viability of restoring the aquatic grass to areas of Back Bay – and to test other areas to see whether the plant does well in those locations. Unfortunately, there is not funding to continue to add to the project, she said. 

More than $75,000 is needed to fund the study in the coming year, including preparing the plants that would be transplanted into the bay on top of continuing study of those already introduced.

State Del. Barry Knight, R-81st District, said he has secured $10,000 for the project through the state this year and possibly the same sum for 2021. He called an effort to restore grasses to the bay a wonderful idea.

“What seems promising is, when the wind blows out of the south, we get flooding a lot faster than we used to,” Knight said during a telephone interview. “Now if we can get these grasses in there, it slows flooding because it causes friction in the water.”

There is no guarantee of city money coming, but Henley and others have spoken in support of the study.

“This Sea Level Wise report has four main pillars, and one of them is the natural mitigations,” Henley said, speaking during the forum at the municipal center. “Certainly, this fits the natural mitigations. … 

“One of the really important ones for the southern watershed is trying to get this submerged aquatic vegetation back in Back Bay to slow the water down. Because we know how fast it comes up now from the Albemarle if we’ve got a strong south wind. So getting that vegetation back is an extremely important part.”

Jared Brandwein, executive director of the Back Bay Restoration Foundation, one of the groups that has helped support the effort, said they want to help the project continue and secure funding.

“It would be nice for the city to give a little bit because it fits right in with their nature-based solutions,” he said during a telephone interview this past week.

He said he wants the project to continue – and continue to provide new data about the restoration of vegetation in and around the bay.

“She’s trying to find the best areas for it to flourish,” Brandwein said. “I think it’s going to get better and better. Even if you have a site that doesn’t do so well, you learn from it. It’s important to be able to do it every year and monitor the previous sites.”

During an interview, Sweeten said the project is still early research and development in which the work is raising questions about methods for restoring grasses — eventually. 

“This is continuing to build,” she said,  “and it’s exciting to see it scale up every year.”

© 2020 Pungo Publishing Co., LLC

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