Bid to revive eelgrass population slowly makes headway in region
DURHAM, N.H. - Swaying underwater meadows of eelgrass once lined the New England shoreline, filtering the water, buffering storm surges, and providing a nursery for a mix of commercially valuable sea life.
Then, this critical coastal habitat was nearly obliterated.
Nature has yet to replace the losses from a mysterious disease that attacked in the 1930s and wiped out 80 percent of the eelgrass population from Maine to North Carolina.
Attempts to bring eelgrass back have largely failed, but scientists are hoping a revival is coming soon. Ongoing genetic analysis and restoration work - including in New Hampshire, Rhode Island, and Massachusetts - aims to help the eelgrass take hold once again.
Some are skeptical of all the attention for an obscure, submerged plant. But advocates say restoring the eelgrass would profoundly improve the local ecology and even the commercial fishery.
Eelgrass is actually a flowering plant that produces leaves that look like long grass blades and lives in waters where adequate sunlight can reach it.
The plant was so common that it was often considered a nuisance. In the early 20th century, it was stuffed into walls as a lightweight insulation and wrapped around ice to keep it from melting during train transport. The thick beds of vegetation also acted as a natural defense during rough weather, helping quiet the waters pounding the shoreline, said Jon Kachmar of The Nature Conservancy, an environmental group leading eelgrass restoration efforts.
But eelgrass was devastated by a parasitic slime mold that remains common to the plant. For unknown reasons, the mold suddenly and ferociously attacked the plants.
“It a natural balance that somehow got out of balance,’’ said Fred Short, a University of New Hampshire professor who is leading genetic studies related to eelgrass restoration.
Most of the damage from the disease was done in the early 1930s, when it quickly spread through leaf-to-leaf contact. The disease wound down in the 1940s, with remaining eelgrass surviving then, as today, in smaller and scattered patches.
In the following decades, the loss of the eelgrass beds was felt all over, scientists say.
For instance, a snail called a limpet that fed on organisms that grew on the grass went extinct.
And commercially valuable bay scallops, which attached to eelgrass blades as juveniles so they could feed and grow up and away from predators, have recently struggled badly, and the disappearance of eelgrass is considered a factor.
Meanwhile, the juvenile shrimp, lobsters, and crabs that found food and hid under the protective canopy of eelgrass became more exposed to predators - including the striped bass fishermen could target as they prowled the beds. Flounder and cod are among the commercially important groundfish that also lost a nursery ground when eelgrass meadows withered away.
Scientists don’t promise that an eelgrass restoration would boost shellfish populations or restore struggling groundfish species, but they say there is little doubt it can help. Kachmar said the loss of the fish nursery grounds can be compared to losing farmland - at some point less land means fewer crops.
“You reach a point where you can only produce so much,’’ he said.
Scientists don’t know why efforts to restore eelgrass have largely failed.
At the University of New Hampshire’s Jackson Estuarine Laboratory in Durham, Short and other researchers hope to discover common characteristics of surviving populations, many of which were found in water with low salinity, where the slime mold appears to struggle.
Work to restore eelgrass populations is also being done at the University of Rhode Island, while the Cape Cod Cooperative Extension and Woods Hole Sea Grant have done test plantings around the Cape to determine where the plant might again catch on.
Outside the New Hampshire lab, on the shores of the Great Bay Estuary at Adams Point, eelgrass grows in several tanks at various levels of sunlight, water clarity and temperature in order to discover which populations might best survive re-planting.
The restoration projects are costly: Transplanting a bed is about $120,000 per acre, while spreading seeds costs about $50,000 per acre. Though success has come slowly, there’s no doubt “progress is being made,’’ said Diane Murphy, who is leading the test plantings on the Cape.