Tisbury looks to preserve, enhance eelgrass in town waterways

The initiative kicked off with a presentation by the Tisbury shellfish constable and the Martha’s Vineyard Commission water resources planner.

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Eelgrass beds provide critical habitat for bay scallops. – Photo courtesy of Danielle Ewart

Eelgrass provides important habitat for juvenile scallops, fish, and all manner of sea life, and is an indicator of water quality. It is also doing poorly or disappearing altogether in Tisbury waters. How to arrest that trend was the subject of an April 5 public presentation by Tisbury shellfish constable Danielle Ewart and Martha’s Vineyard Commission (MVC) water resources planner Sheri Caseau.

The pair provided an informative presentation in which they outlined likely causes of eelgrass disappearance, and measures that may be taken to increase eelgrass beds. These could include new restrictions on anchoring, fishing methods, and mooring tackle. One challenge is how to balance recreational and commercial activities with efforts to preserve eelgrass. Tisbury selectmen agreed to create a committee to specifically look into the issue.

Eelgrass, which grows on the seafloor in shallow coastal waters, has long been a major concern on the Island. An eelgrass bed — often a dense, extensive patch of grass — provides shelter for a wide range of sea life, and is critical bay scallop habitat. Eelgrass is already beleaguered in Massachusetts water, in part due to excess nitrogen in coastal waters, which generates higher densities of algae, competing with eelgrass for light. Eelgrass is also vulnerable to bottom disturbances.

“The Massachusetts Estuaries Project (MEP) uses eelgrass recovery as the primary indicator for the health of the ponds,” Ms. Ewart said Tuesday.

In addition to providing habitat for sea life, the roots stabilize the seafloor, reducing shoreline erosion. The plant itself catches suspended sediment, which improves water clarity, and sequesters nitrogen, carbon dioxide, and carbon while producing oxygen.

Community input

Fishermen and boaters were among those in attendance Tuesday. “Anchoring and scalloping have always been there; they’re not what’s made the eelgrass go away,” Tisbury resident and tugboat captain John Packer said. “I know it’s an easy solution to say, Stop anchoring to save the eelgrass, but that’s not what killed the eelgrass.”

He suggested the town collect more data on what’s causing the eelgrass problem, and look into aquaculture solutions.

Commercial fisherman Lynne Fraker suggested expanding eelgrass education in town, and creating a group to look specifically at solutions to the problem. Selectmen Tristan Israel agreed with the suggestion, and proposed looking into the issue again in May.

“I ask that we all think about that, and once we get through town meeting in the next couple weeks, come back and make a proposal to set up a group to look at all these issues, to look at the definitions of the maps and have a conversation, and see if we can come up with a direction rather quickly at that point,” he said.

The consensus among the majority of people at the meeting was that more measures be put in place to protect eelgrass. “We all want to see the eelgrass protected,” charter fisherman and artist Jeff Canha said. “I don’t think anybody doesn’t want eelgrass, but how can we protect it and still enjoy our waters?”

Coastal problem

Eelgrass has been slowly disappearing over the years from Tisbury waters. Over a roughly 18-year period from 1995 to 2013, MEP researchers mapped Lake Tashmoo and Lagoon Pond eelgrass beds from the air and the water. The MEP reports that from 1995 to 2001, eelgrass coverage in Lake Tashmoo dropped from 91.17 acres to 50.16 acres. “That’s 45 percent eelgrass coverage loss in Tashmoo,” Ms. Ewart said.

The loss is even greater in Lagoon Pond, dropping from 164.57 acres in 1995 to 51.36 acres in 2006, “and there’s even more now,” Ms. Ewart said. In total, it’s a 69 percent loss of coverage in Lagoon Pond.  

Eelgrass loss is not restricted to Vineyard waters, however. Ms. Ewart reported that coastal communities from Brewster to the Caribbean have experienced similar losses, and many towns are taking measures to protect the sea plant.

Nantucket established habitat-sensitive areas that allow the town to close off areas to anchoring, boat traffic, and shellfishing as necessary. Falmouth and Wareham conservation commissions expanded the Wetlands Protection Act to include areas of and adjacent to eelgrass, which ensures that projects have minimal to no impact on the plant beds. Florida has strict policies along its coastlines, and levies fines for resource damage.

Plant preservation

Tisbury is looking to follow suit. Several efforts to preserve eelgrass beds are already in the works. One potential solution is to grow more eelgrass. Last summer, Ms. Ewart and Ms. Caseau, with assistance from the Environmental Protection Agency (EPA), started an experiment using healthy blades of eelgrass put into mesh bags and placed on test buoys throughout Lake Tashmoo.

“It’s very low-cost; you just take the bags out, suspend them, and they disperse on their own,” Ms. Caseau said. “We’re going to see if that works; we’re going to try it again, and we’re going to try it in different areas.”

Another tactic is public education, Ms. Ewart said. Signs at the Lagoon Pond boat ramp and at Owen Park provide information on the importance of eelgrass. More signs and more efforts to get the community actively involved in eelgrass preservation are possible, she said.

Other, more aggressive approaches could include restrictions on anchoring in specific areas to protect eelgrass, and an expansion of the Wetlands Protection Act.

The Army Corps of Engineers, which is responsible for the nation’s waterways, already stipulates that moorings be converted from conventional to conservation moorings when there is a change in ownership or a necessary replacement. Conservation moorings eliminate ground tackle from dragging on the bottom and disturbing surrounding eelgrass beds.

Any changes would be subject to a public hearing process.

Committee takes charge

Some potential changes are in the works. The shellfish advisory committee has asked selectmen to prohibit the use of teeth on scallop drags, a topic of contention in the fall. In November, Tisbury selectmen held a public hearing after Ms. Ewart proposed a moratorium on the use of shellfish drags with teeth, which she said can cut through and damage eelgrass. At that time, selectmen voted to take no action, and asked the shellfish committee to come up with a regulation banning the use of teeth starting with the 2016 season.

Scallopers tow specialized drags to harvest the prized shellfish. It is not unusual for one boat to tow four drags, essentially a bag on a metal frame that utilizes a chain-mesh bottom to keep the bag tight to the seafloor, scraping up scallops.

So there would be no confusion about what constitutes “teeth,” the committee defined it as “drags with teeth, tines, rakes, scoops, or anything the Constable deems harmful to the pond.”

Nitrogen obstacle

Excessive nitrogen loading remains a major factor influencing the Island’s water quality. Last year, all Island towns adopted a set of regulations governing the use of fertilizer, one of the chief sources of nitrogen.

The town has undertaken a number of measures to control nitrogen loading that include the use of rainwater catch basins to limit runoff.

The Tisbury wastewater planning committee has identified nitrogen control and protection areas, which now include the entire watersheds of Tashmoo and Lagoon Pond.

The Tisbury board of health has also been working on regulations to prevent new nitrogen from entering into those identified watersheds in Tashmoo and Lagoon Pond. Public hearings will be held on those regulations in the months following town meeting.

Furthermore, a joint Oak Bluffs and Tisbury wastewater planning committee, with the help of the MVC, applied for a significant EPA grant for technology that would remove nitrogen from the groundwater in the Lagoon watershed. The group has made it through the first part of the two-stage grant, and will likely hear back about the results of the process in June.

“There are a lot of things happenings,” selectmen Melinda Loberg said Tuesday. “Underneath the radar screen, there’s an awful lot being done about nitrogen.”