When it comes to tedium, little can match the drudgery of planting underwater grass beds. People have to work hour after hour—often in diving gear—pushing plants one by one into the sediment and securing them so they won’t wash away in the first storm that comes by.
“It’s extremely tedious,” said Bob Orth, a seagrass expert with the Virginia Institute of Marine Science. “That’s one of the reasons I’ve gotten out of it.”
Instead of doing plant-by-plant restoration, Orth and his colleagues have taken to riding in boats, and flinging seeds into the water by the handful. Instead of taking days to plant tracts that are measured in square meters, they cover acres in a single day.
By some estimates, Orth and his team have planted almost as many acres by seeding in the past three years as all of the other Bay grass restoration efforts combined over the past two decades.
The idea is catching on across the Bay. Many who have been active in underwater grass restoration now think that seeding may be the way of the future, especially if large areas of grasses are to be restored.
It may be the only way, some believe, that the Bay Program can achieve a goal in its new underwater grass restoration strategy. Adopted earlier this year, the strategy calls for planting 1,000 new acres of submerged aquatic vegetation—SAV for short—by the end of 2008, or roughly 200 acres per year.
“That’s a pretty ambitious goal, given the scale at which plantings are occurring right now,” said Deborah Shafer, a research marine biologist with the Army Corps of Engineers Engineering and Research Development Center, which sponsored a workshop on SAV propagation techniques in September.
With an eye toward promoting large-scale SAV restoration projects, Congress provided $500,000 each to the Army Corps of Engineers and to the National Oceanic and Atmospheric Administration’s Chesapeake Bay Office to step up research and planting efforts.
Of the various planting techniques, though, seeding seems to be picking up the most steam because it is relatively easy and avoids the problem of finding adult plants for restoration projects, which can be a problem. Generally, plants are either dug from existing, healthy grass beds—which is controversial—or grown in labs or greenhouses—which is expensive, often costing several dollars per plant.
Seeding is also the technique that most mimics Mother Nature, who creates new grass beds as mature plants flower and broadcast their seeds into nearby areas.
“I like to think of it as cutting out the middleman,” said Mike Naylor, a biologist with the Maryland Department of Natural Resources. “When you plant mature plants, all you are doing is hoping that they will create seeds that spread. If the seeds from the adult plants can’t start new populations, you are wasting your time. By skipping the adult plant stage and putting seeds in, you can get a lot more bang for the buck.”
Orth tried planting with seeds in the 1980s, but the results seemed to be patchy, and most of his focus—and that of others working on SAV restoration—turned to planting adult grasses in the sediment.
But the labor involved in trying to plant small tracts, which sometimes are washed away by storms or smothered by sediment, made him take another look at seeding. “After you do plantings for a while, you think there has to be a better way,” he said.
His new look was also spurred by observations in Chincoteague Bay on the Atlantic side of the Eastern Shore, where grass beds have expanded an average of 600 acres a year for the past decade with no restoration activity—something happening strictly through natural seed dispersal from the plants.
Orth and colleagues began gathering millions of seeds from eelgrass beds in the spring—a single person can collect more than 30,000 seeds an hour under the right conditions—and storing them in special tanks until fall, when eelgrass naturally germinates. Then crews go out by boat and toss seeds into the water by hand.
In 2001, they planted 42 acres, followed by another 32 acres last year, with more planned for this fall.
Initially, seeding appears to give poor results: Only 5–10 percent of the seeds germinate. But follow-up monitoring showed that what starts out as sparse patches quickly begins to fill into thicker beds. “Once you get a bed in there, if they are not compromised by water quality, these things spread like crazy,” Orth said.
So far, though, most seeding work has been done with eelgrass, a species that lives in saltier portions of the Bay. More research is needed to see how well the technique works with freshwater species.
“We really haven’t tested that much for wild celery and redhead grass,” said Peter Bergstrom, of NOAA’s Chesapeake Bay Office. “It should be possible. But it’s a question of how do you do it, when, and how do you treat the seeds.”
Bergstrom said he would also like to find ways to improve the germination rate for seeding efforts, which is poor compared to the survival rate for hand-planted grasses. “To me, it is a cause for concern that the survival with eelgrass seeds is only 5–10 percent,” Bergstrom said. “We could do more with the same number of seeds if we could improve that.”
He and others hope the germination rate can be increased over time as new and better techniques are developed.
One alternative to seed collection and storage that drew interest at the September workshop was a technique developed on Long Island Sound by Chris Pickerell, of Cornell Cooperative Extension in New York. He takes flowering shoots from eelgrass plants and places them in mesh bags that are moved to the planting location, then attached to anchored buoys laid out in a grid.
The seeds mature and are released from the shoots—just like they would in a natural grass bed—and pass through the bags to disperse in the surrounding sediment. It’s a technique that can easily be adapted for use by volunteers to plant large areas, Pickerell said.
“There’s a lot of interest in doing that in the Chesapeake Bay and with different species,” Shafer said. “His idea is nice, and low tech and low cost.”
Steve Ailstock, director of Anne Arundel Community College’s Environmental Center, said the growing interest in seeding helps to move restoration efforts out of the “hunter-gatherer” mode into techniques that more resemble agricultural methods—a transition that he said is necessary if large-scale restoration efforts are to become successful. The next step, he said, may be creating seed farms to mass produce desired varieties of grasses specifically for the purpose of harvesting their seeds for restoration.
“We’re following a really good model,” he said. “But it’s important that we don’t lose sight that water quality is critical to success. I don’t care how good your farming logic is, you are not going to grow wheat in Saudi Arabia.”
There are other barriers as well. Predators, such as mute swans and other resident waterfowl, can literally take a bite out of restoration projects, especially in mid and upper portions of the Bay, where the herbivores are most numerous. “There are some projects where I spent almost as much on fencing as I did on plants,” Bergstrom said.
Ironically, what draws the predators to the grass beds is the same thing that draws biologists seeking to restore the plants: a huge abundance of seeds. Redhead grass, Ailstock said, produces between 8,000 and 30,000 seeds per pound of plant. “Whether you are a seed collector or a duck, it’s all about calories per unit of work.”
Because of intense predation pressure, some believe that the best way to restore plants in certain areas will be hand planting adult plants in fenced “founder colonies” in the hope that they will eventually produce enough offspring to gradually expand.
Indeed, even if seeding becomes the wave of the future, everyone sees some role for hand planting. Plants, for instance, need to be placed in areas before seeding projects take place to determine whether water quality is good enough to support underwater grasses.
Rearing grasses and placing them in the water is also a powerful educational tool, used in such programs as “grasses in classes,” which helps people learn about the value of SAV.
“There is absolutely a role for parent plants,” Naylor said. You learn something by putting parent plants in and seeing if they survive that you never learn from seeds.”
But for large-scale projects, he said, seeds are the way to go. He and others are even thinking of using harvesting equipment that would trim off the top, reproductive, portion of plants while leaving the rest intact—a method that might yield tens of millions of seeds in a day’s work.
Naylor said that, outside of Orth’s seeding projects, the total amount of SAV planted in the Bay over the past two decades amounts to only about 50 to 100 acres, and no one is certain how many of those areas survived.
But he envisions those efforts being dramatically ramped up in coming years. Naylor said the day may come when grass beds may be seeded by airplane, a technique used to plant rice paddies. “A plane can plant 1,000 acres a day,” he noted. “We’re a long way from being able to do this by airplane, but the potential is there, I think, to make a really great leap beyond what’s been done historically.”