Raking up Bay grass beds in a bid to restore them

Restoring the Chesapeake Bay’s depleted underwater meadows is a painstaking process, requiring lots of elbow grease, savvy and patience. Paradoxically, it begins by pulling up a little of what’s left of the critical aquatic habitat.

Standing knee-deep in the Wye River on Maryland’s Eastern Shore, Elle Bassett and a handful of helpers raked clumps of wispy green grass from the water one warm June day. They piled the vegetation, known as horned pondweed, in orange plastic baskets for transport by boat to shore.

“This one is easier than others to harvest,” noted Bassett, the Miles-Wye Riverkeeper. Some species of Bay grass are more firmly rooted in the bottom, she explained, and have to be collected one handful at a time.

For the last four years, Bassett and other staff and volunteers with the nonprofit group ShoreRivers have been working with experts from the Maryland Department of Natural Resources and Anne Arundel Community College learning how to restore Bay grasses.

“We’re doing what I would call a ‘technology transfer’” said Mike Naylor, a DNR biologist specializing in the Bay grass restoration effort who was on hand to help.

Now, with a $75,000 grant from the Chesapeake Bay Trust, ShoreRivers has ramped up its efforts, with a focus on mid and upper Eastern Shore waters. Their aim: to double the state’s overall restoration capacity.

A lot is at stake. Bay grasses, also known as submerged aquatic vegetation, or SAV, are a vital component of the Chesapeake ecosystem. They provide food and shelter for waterfowl, turtles, fish, blue crabs and other creatures. They also consume some of the excess nutrients that foul the water, clearing it up and infusing it with fish– and shellfish-sustaining oxygen. For those reasons, the grass beds are closely monitored as an indicator of the Bay’s health.

Like the rest of the Bay, the grasses need all the help they can get. Historical photos show that they once covered at least 185,000 acres of the bottom of the Chesapeake and its tributaries, and probably much more. But by 1984, with the Bay suffocating from nutrient and sediment pollution, the coverage had dwindled to just 38,227 acres.

Bay grasses are so important to the estuary’s health that federal, state and local agencies and nonprofit groups have been trying for decades to restore them, with mixed results.

Rebound, then regression

A few years ago, it looked like the Bay’s grasses were rebounding quite well on their own. By 2018, aerial surveys spotted underwater vegetation growing across more than 100,000 acres of Bay and river bottom, well on their way to achieving the restoration effort’s goal of having 130,000 acres by 2025.

Water quality has proven to be a major factor, both in the past decline of the Bay’s aquatic plants and in the recovery seen so far. Like upland vegetation, underwater grasses need sunlight to grow. But sediment or nutrient-fed algae blooms cloud the water, which stunts or even kills the plants.

“It really only required a modest improvement in water quality for SAV to improve,” noted Brooke Landry, a DNR biologist and chair of the federal-state Chesapeake Bay Program’s SAV workgroup.

But 2018 and 2019 brought heavy and persistent rains, which clouded the water and altered its salinity — another critical factor for sustaining certain species of underwater vegetation. The Bay’s grasses shrank by 40% in 2019 and by another 7% in 2020, the surveys found.

Now, manual grass restoration efforts, which seemed almost superfluous just a few years ago, have taken on renewed importance.

“I think every little bit does help,” Landry said.

For a while, in the 1990s and early 2000s, comparatively more money and effort were put into replanting lost aquatic grasses. There were some notable successes, such as the restoration of eelgrass beds in the seaside bays of Virginia.

In Maryland, biologists at Anne Arundel Community College figured out how to raise Bay grasses from seeds collected from the wild. They set up an aquatic plant nursery there capable of producing batches of underwater vegetation.

Around 2000, the Chesapeake Bay Foundation and the DNR teamed up to get students in more than 300 Maryland schools to grow aquatic vegetation in their classrooms and then take it out to plant on the Bay bottom.

Those broad-scale efforts succeeded in replacing some missing grass beds in places such as the Severn and Magothy rivers in Anne Arundel County. But they were “expensive, time-consuming and laborious,” Naylor said. The results also proved to be spotty overall, and funding dried up.

Out of necessity, the effort shifted to a lower gear.

“Instead of doing huge projects, we’ve been concentrating on small-scale restoration efforts of an acre or less,” Landry said. They’ve also chosen to skip the logistical challenges of raising aquatic plants in nurseries or classrooms and instead sow the seeds directly on the bottom.

The aim, she said, is to plant about 20 acres a year, roughly evenly divided between Maryland and Virginia.

“We started working with waterfront homeowners,” she explained, “planting little, tiny half-acre projects, just placing seeds offshore.” Those have worked, she said, in places like the upper Chester River.

“The hard part is collecting and processing seeds,” Landry added. Care must be taken to find grass beds lush enough they can afford to give up some seeds and still sustain themselves. Collectors limit their harvests to no more than a third of those beds.

Focus on the Shore

The aerial SAV surveys conducted by the Virginia Institute of Marine Science help to identify candidate sites for seed collection, but ground-truthing is still vital.

The patch of horned pondweed harvested in June had never been spotted from the air, noted Bassett, the Miles-Wye Riverkeeper. It was instead discovered by a ShoreRivers volunteer who routinely scouts local waters to check on grass beds.

ShoreRivers is focusing its efforts on restoring grasses in the four Bay tributaries in the mid and upper Shore. Of the rivers in those regions, only the Sassafras has a healthy stock of underwater vegetation, which has at times met and even exceeded the acreage goals set by the federal-state Bay Program. It’s lost ground lately, though, like much of the rest of the Bay.

Grass coverage in the other rivers — the Chester, Miles-Wye and Choptank — is well below acreage targets considered sufficient for ecosystem health.

Complicating restoration efforts: Each river has a different type or mix of underwater vegetation — horned pondweed, widgeon grass, redhead and wild celery — each with its own characteristics and optimal growing conditions.

“SAV is almost as elusive as crabs in determining their patterns,” said Annie Richards, the Chester Riverkeeper.

The grasses harvested by ShoreRivers staff and volunteers are being taken to Chestertown, where the group has forged a partnership with Washington College to process and store the seeds for replanting the next spring. The harvesting, processing and storage all follow a tried-and-true script worked out by experts at Anne Arundel Community College. But one important challenge remains: getting the grasses to grow again where they vanished years ago.

“You can collect all the seed you want, and we are really good at keeping it and storing it properly,” said Mike Norman, lab manager at Anne Arundel Community College’s environmental center. “But we really have to work on getting it out in the field in successful projects.”

‘We can get people involved’

The DNR’s Naylor said he hopes the ShoreRivers undertaking can be replicated by other riverkeeper and watershed groups around the Bay. But it’ll take more funding, he noted.

While the acreage they’re able to restore may be small compared to what’s needed, Naylor said it also helps to engage and educate the public about the value of aquatic plants, which were once routinely eradicated because boaters complained about the grasses fouling their propellors.

“We can get people involved, to care about it,” he said, “so they appreciate SAV and don’t look at it as a pain in the butt.”

The Bay Journal provides the public with independent reporting on environmental news and issues in the Chesapeake Bay watershed.