There is much ado over eelgrass. On the Vineyard the modest sea grass has brought dredging projects to a halt, thwarted would-be pier developers and has down-Island towns considering millions of dollars worth of sewering to restore water quality to a level amenable to the light-sensitive plant. Why all the fuss?
By some estimates, the world has lost two-thirds of its sea grass habitat due to coastal human pressures and is losing an additional seven per cent every year. On the Vineyard those losses have been even more dramatic, as overlays of current eelgrass beds compared with their historic distribution are uniformly depressing: Edgartown Great Pond alone has lost 90 per cent of its eelgrass since 1951. During the same period Sengekontacket lost 97 per cent, from 220 acres to just five and a half in 2006. In the last two decades Lagoon Pond has lost half its eelgrass beds, a fact not lost on shellfisherman Bill Alwardt who says that even in the past year he has seen a major die-off in the most well-flushed area of the pond near the mouth. And this week Dr. Brian Howes, a southeastern Massachusetts marine biologist who is directing the Massachusetts Estuaries Project, told an unreceptive Chilmark board of selectmen that 100 acres had been lost in Chilmark’s ponds since 1995.
Eelgrass is a vascular plant, one of 60 species of sea grass worldwide that evolved from land plants some 100 million years ago and returned, whale-like, to the sea. Eelgrass flowers, pollinates and produces seeds, all underwater, forming large patches called meadows or forests — a nod to the plant’s terrestrial past. As photosynthesizers, they require plenty of light. Plenty of light means clean water and when water quality degrades the plants can serve as coastal canaries, dying en masse, as they have on the Vineyard.
Sea grasses, like eelgrass, also buffer against coastal erosion, sequester carbon, and perhaps most important, serve as a nursery for bay scallops and fish species like herring, which in turn attract larger predators like bluefish and striped bass.
“When the grassbeds are gone, those fish may come into an estuary in their northern migration, but they won’t stay there because there’s no habitat and no food and they’ll just move on until they get far enough north that they can find healthy grass beds,” said Fred Short, a professor of natural resources and the environment at the University of New Hampshire and one of the world’s leading sea grass experts.
And sea grass is unsung. According to one study, salt marshes, mangroves and coral reefs receive up to 100-fold more media attention than sea grass ecosystems, while sea grass habitat is at least twice as economically valuable. For the Vineyard, the economic value of eelgrass is acutely felt as the setting for the Island’s bay scallop industry.
It’s why for years Oak Bluffs shellfish constable David Grunden has tried with limited success to restore at least some part of the plant’s historic range. He says he has undertaken at least three restoration projects in Sengekontacket with funding from both his town and the Martha’s Vineyard Commission.
Mr. Grunden tried several different methods, from transplanting plants whole to direct seeding, to no avail.
“We haven’t had any success,” he said. “They all died within a few weeks.”
The Vineyard is not alone in its struggle to bring back the fragile habitat. At Boston’s Logan Airport where a massive runway extension project is underway, Massport has had to embark on an equally ambitious EPA-ordered eelgrass mitigation project to offset the new development.
“They basically dredged or covered up a large eelgrass bed and they had to move that bed to different places in Boston harbor but it didn’t do very well,” said Mr. Short.
On Cape Cod, efforts to restore eelgrass have been similarly ineffective. Fisheries and aquaculture specialist Diane Murphy at the Woods Hole Oceanographic Institution’s sea grant program has been involved in a number of restoration projects, some of which have relied on some rather unusual equipment. In restoration efforts in Pleasant Bay in Orleans, Town Cove in Eastham, and Popponessett Bay in Barnstable, Ms. Murphy’s team dragged an aluminum sled in rows through the sediment dispensing a mix of eelgrass seed and gelatin.
“The hopper was actually retrofitted equipment that was used to insert jelly into jelly doughnuts,” she said.
Over the past two years, Ms. Murphy, working through the Cape Cod Cooperative Extension Marine Program with a $73,000 grant from The Nature Conservancy, identified three more sites in Orleans, Bourne and Truro where eelgrass flourished historically and that were deemed ideal for reintroduction. Over the past year shifting sands, an influx of crabs and a decrease in water clarity, possibly from storms, conspired to kill off nearly all of the plantings.
“Our results are very common to a lot of restoration projects,” she said. “You’ll hear the advice: Don’t even attempt it until the water quality is improved, it’s putting the cart before the horse. Everyone wants to jump into eelgrass restoration, it’s sexy, it’s fun to restore something, but the behind-the-scenes efforts to improve water quality, that’s the unsung hero.”
Improving water quality is where science intersects with public policy. One solution currently being pursued by towns across the Cape and the Islands is sewering. Nitrogen from septic systems filters into groundwater and eventually into estuaries and is perhaps the largest contributor to degrading water quality (nitrogen acts as plant food, spurring the growth of algae that robs eelgrass of light and, when it decays, can turn waters anoxic). Done correctly, Ms. Murphy says sewering could alleviate some of the stress from individual septic systems. But she cautions against the influence of increased wastewater capacity.
“You can’t disagree with sewering,” she said. “Sewering would be a better alternative than individual septic systems and we have to do something. On the other hand I worry that sewering will permit further sprawl. In areas where the case is made that it’s too sensitive, that we shouldn’t build there, that defense will be taken away.”
Mr. Short agrees.
“Lot sizes for development have been based on having sufficient area to treat wastewater, so if you go to sewers the question is will you make smaller lot sizes and then it’s how small can you get?”
Careful planning and implementation could turn the tide against eelgrass loss but with the habitat vanishing in areas as far afield as the Baltic, the Mediterranean, Japan, the Chesapeake and here at home, Mr. Short said it may be too late.
“The timing is the problem,” he says. “It’s declining very rapidly at the moment. It’s sort of in an exponential decline phase that will level off at some point when the most vulnerable beds are gone. But by the time that happens we’ll lose a lot of the value and function of those grass beds and that’s going to change our quality of life in coastal areas.”
Unchecked, Mr. Short said, eelgrass will come to be replaced by seaweed and drift macroalgae.
“That stuff ends up washing up on the beach and rotting and smelling bad and all the people that have their fancy houses on the beach don’t like black, rotting seaweed,” he said. “When it gets really bad it actually takes the paint off your house. It’s not a fun experience”