Mike Norman grabbed a handful of seeds. Then he thoughtfully offered words of warning. “I apologize in advance if I hit you with the backwash in my throw,” he said. “This is not a perfect science.”
With a gentle sidearm motion, he tossed scores of widgeon grass seeds — a species that may be key to restoring the once-vast underwater meadows in much of the Bay — into the Magothy River.
Splashes pock-marked the chocolate-milk colored water as the seeds disappeared below the surface. “They’re negatively buoyant, so they will sink,” said Norman, who has been working with underwater grasses for years at Anne Arundel Community College.
He grabbed another handful and tossed them into the water as he and Mark Lewandowski, a natural resources biologist with the Maryland Department of Natural Resources, continued “planting” 3.5 acres of aquatic grasses in the river on a late spring day.
Their labors were part of a Bay Program effort to plant 20 acres of underwater grasses annually in the Chesapeake — half in Maryland and half in Virginia.
Underwater grasses are a key part of the Chesapeake ecosystem. They provide habitat for small crabs and juvenile fish, and food for waterfowl. They alter and improve fish habitats as their roots stabilize sediment, and larger beds help to buffer shorelines from the erosive power of waves. They soak up nutrients and pump oxygen into the water.
While Bay grass acreage has been on the rebound in recent years, the 91,620 acres seen in the Chesapeake last year is still less than halfway to the overall goal of 185,000 acres, which was based on historic abundances.
By planting beds in places like the Magothy — where there’s been little submerged aquatic vegetation for decades — biologists hope they can accelerate recovery.
But meeting Bay goals in moderately salty water, like in this Western Shore river, remains challenging. In large part, that’s because of the finicky nature of the plants Norman and Lewandowski were trying to jump-start.
Widgeon grass, (Ruppia maritima) is notorious for being a boom-and-bust species that proliferates when conditions are just right, then disappears just as quickly — sometimes for little obvious reason. From 2002 to 2003, for instance, scientists say as much as 60 percent of the widgeon grass in the Chesapeake vanished. Such swings are significant, because year-to-year changes in Baywide underwater grass abundance are often largely driven by the fortunes of widgeon grass that year.
“Ruppia has always been a mystery to me,” Norman said. “A 10-acre patch will come out of nowhere one year, and it’s completely gone the next, and you will see it somewhere else. But it’s still a good plant.”
In fact, it is an essential plant for meeting Chesapeake goals. The majority of the Bay’s potential underwater grass habitat, 120,306 acres, is in the moderate-salinity, or mesohaline, zone that stretches from near Baltimore south to the Rappahannock River and Tangier Island.
“In the middle part of the Bay — the mesohaline — widgeon grass is by far the dominant species,” said Bob Orth, of the Virginia Institute of Marine Science, who oversees the annual aerial survey of Bay grass beds. “In most places, it probably is the only species.”
Last year, that middle region had 47,728 acres of grasses, the most since 2002. But it was still just 40 percent of the 120,306-acre goal for the mesohaline zone. That area of the Bay is further from its restoration goal than any other sector.
Widgeon grass does well in the Mid Bay because it tolerates a wide range of salinities. It is, in fact, one of the most widespread underwater grass species globally.
But it also has disadvantages. Other important underwater grass species are perennials, with roots and stems that survive through the winter and revive the next year. They expand through the distribution of seeds and plant parts.
In contrast, widgeon grass — at least in the Chesapeake — “is a weak perennial,” said Steve Ailstock, a biology professor at Anne Arundel Community College, and one of the few people to have worked extensively with the species in the Bay. Its overwintering plant structure is less extensive than other species. And in some areas, Ailstock said, widgeon grass doesn’t appear to be a perennial at all.
“It’s like tomato plants,” he said. “Tomato plants are perennials in Louisiana; they are annuals in Maryland.”
The shallow root system of widgeon grass makes it less durable in more exposed, deeper waters, especially when there are no other underwater grasses around to shield them from uprooting by waves.
Historically, widgeon grass was just one of several species found in the Mid Bay. In lower salinity parts of that region, it was joined by redhead grass and sago pondweed, for instance. In higher salinity areas, it mixed with eelgrass.
With multiple species present, each able to tolerate slightly different conditions, the likelihood increased that some plants would survive each year, helping to create conditions needed for other grasses to spring back.
That diversity was lost after Tropical Storm Agnes in 1972, which wiped out huge swaths of underwater grasses throughout the Bay.
Widgeon grass may have been able to make a comeback where other plants didn’t because it is a prodigious seed producer. And, those seeds have a hard coating which appears to help them survive for years in the wild, allowing plants to bide their time until conditions are right, then explode in abundance.
“The seeds may be there, but they may not be sprouting. I think that goes a long way toward explaining the variability in Ruppia concentrations,” Ailstock said. “From a botanist’s perspective, it’s not a big surprise that’s the way it works.”
Ailstock said the amount of widgeon grass in the Bay probably always fluctuated widely. Before Agnes, though, the beds were probably larger and denser, and therefore produced even more seeds. In “down” years, the beds were likely somewhat smaller, and less dense — but still present.
Because it comes and goes so unpredictably, widgeon grass has received less restoration attention than many of the Bay’s other species. Most underwater grass plantings in the Chesapeake already fail, and scientists have had little interest in working with widgeon grass because the odds are even lower that a newly planted bed will survive over time.
“If your goal is restoration success, it is hard to measure,” Norman said.
But over the years, Ailstock has maintained widgeon grass among the mix of underwater vegetation that he and his colleagues and students cultivate.
They’ve been figuring out the best ways to harvest the seeds, then separate them from the attached plant material. It’s accomplished with a custom-built device called a “turbulator,” which operates like a giant washing machine.
They’ve done laboratory work over the years to understand the temperatures and salinities which produce the best germination results. “It is literally agriculture/gardening 101,” Ailstock said.
For many years, they grew widgeon grass in the laboratory, producing plants that could be planted by hand in the Bay and its tributaries. But it quickly became obvious that was not the way to restore grass beds — placing plants three inches apart requires 700,000 plants per acre, Ailstock noted.
So in places like the Magothy, they are testing a new approach. On that spring day, instead of placing individual plants by hand, they were “hand broadcasting” seeds from a small boat. In addition to tossing hundreds of thousands of widgeon grass seeds into the river, they were also tossing redhead grass and sago pondweed with the hope of bringing back the more resilient variety that once flourished in the region.
“You’re basically hedging your bets, putting out a mixture rather one species,” said the DNR’s Lewandowski. The Magothy is the first DNR planting project to try the widgeon grass mix.
Getting multiple species to take root is still a challenge, as each has different ideal conditions for germination. And there’s still a lot that could go wrong. The weather — and therefore salinities that greatly affect germination — can’t be controlled. Nor can predators.
“This is premier duck feed,” Norman said, as he tossed out some sago pondweed tubers. And widgeon grass, after all, is named for a duck that likes to eat it.
Ultimately, if large-scale plantings are going to take root, Ailstock said, more work needs to be done to gain critical information, such as how quickly seeds will germinate in different types of sediment and conditions.
In all types of agriculture, whether corn or underwater grasses, Ailstock said, “you want to get them through the seedling stage as rapidly as possible because that’s when they are most vulnerable to a ton of things.”
Planting techniques could also be improved. Ailstock noted that if someone simply tried hand-tossing seeds to plant agricultural crops, even if done from a plane, “you would likely conclude that you could never grow corn and soybeans on the Eastern Shore of Maryland.”
In late August, Norman and Lewandowski returned to the Magothy to see if their spring planting paid off.
Along the causeway to Gibson Island, one place where they scattered seeds, they found spotty patches of bright green widgeon grass. Altogether, Lewandowski said, there was about a quarter acre.
“There’s never been widgeon grass reported there or observed,” he said. “It was in really good shape.”
That’s especially good news, Lewandowski said, because the seeds the biologists were planting had been in storage for several years.
“The fact that we got a quarter acre out of older seeds gives us some pretty good optimism," he said.
Neither the sago pondweed nor the redhead grass appeared to take root, Lewandowski noted, though some redhead grass that had popped up nearby late last year moved into the area.
Biologists worked with volunteers from the Midshore Riverkeeper Conservancy to harvest widgeon grass seeds from robust beds on the Eastern Shore’s Miles River this summer. They are looking forward to expanding widgeon grass planting next summer.
“We know the technique works,” Lewandowski said. “Now that we know a little more and have a fresher batch of seeds, I think we can expect a lot more acreage in return for next year.”