Environmentalists keeping close eye on eelgrass growth in Sound

Some motor boat operators and anglers may think of eelgrass only as the slender green blades that get tangled around propellers and fishing lines.

But what some consider a nuisance is really a vital part of the Long Island Sound estuary, one environmental managers are working to see someday restored to a greater swath of its historic range.

"Just like you're not going to have forest animals without forests, we're not going to have a healthy, diverse Long Island Sound without the habitats eelgrass beds provide that are so critical," said Mark Tedesco, director of the federal Environmental Protection Agency's Long Island Sound Study.

In a newly released survey of eelgrass beds in eastern Long Island Sound - the only part of the Sound where they still grow - federal researchers found 1,980 acres of eelgrass from Clinton harbor to Little Narragansett Bay and around Fishers Island. In the 172 beds studied with aerial photographs and underwater cameras in 2009, the researchers tallied a total loss of 46 acres compared to three years earlier, with some areas gaining and others declining.

"If there was a great decrease, we'd be alarmed," Tedesco said.

Little Narragansett Bay saw the most gain from 2006, with 60 new acres added to the bed now measured at 343 acres, the third-largest. The biggest losses were seen in Niantic River Bay, where 212 acres were found, 57 less than in 2006.

Separate from the eelgrass work, projects addressing water quality problems in the Niantic River watershed are under way.

Eelgrass beds provide habitat for many juvenile fish species and shellfish and improve water quality by helping capture suspended particles and keeping bottom sediments from being stirred up into the water. But the beds cannot grow where water is overloaded with nutrients that feed algae blooms and block light, or where sediment muds have too much phosphorous, nitrogen or sulfur, said Julie Rose, the National Oceanic and Atmospheric Administration's liaison to the Long Island Sound Study. Polluted stormwater runoff and inadequately treated discharges from sewage plants and septic tanks are the main sources of the nutrients and sediment contaminants.

Tedesco cautioned that the survey should be viewed as a single snapshot of the distribution and density of eelgrass in the Sound, not by itself cause for concern or celebration about certain areas, but indicating areas that should be watched. The survey must be continued to see long-term trends, he said.

"We think it is so important to continue this," Tedesco said, adding that some year-to-year gains and losses have natural causes and others are due to human actions, such as those that lessen or exacerbate water pollution. "There's been a swelling of interest in eelgrass and work to help understand its abundance and health and what we can do to restore it."

Historically, Tedesco noted, eelgrass grew throughout Long Island Sound, but poor water quality in the western end caused beds to die off there.

The work by the U.S. Fish & Wildlife Service's National Wetlands Inventory Program was done for the Connecticut's Department of Environmental Protection's Office of Long Island Sound Programs, one of the partners in the Long Island Sound Study, and was funded by the EPA. It follows two earlier eelgrass surveys, in 2006 and 2002.

Harry Yamalis, environmental analyst for the DEP, said the state will use the survey to help identify areas where water quality and habitat restoration projects should be considered.

In September, two University of Connecticut professors will begin a project that builds on the eelgrass survey work. Working with Long Island-based researchers, they will identify specific areas in the Sound with water quality, sediment and other characteristics conducive to eelgrass growth, said Jamie Vaudrey, assistant research professor in marine sciences. She is based at UConn Avery Point in Groton.

"Water quality has improved in some areas of western Long Island Sound, so there are areas that could now support eelgrass," she said. "What's missing is a source of seeds. We'll plant a restoration bed, and then it will seed itself."

j.benson@theday.com

EELGRASS LEADERS

Largest eelgrass beds in Long Island Sound:

• Quiambog Cove, Stonington: 407 acres

• Fishers Island: 346 acres

• Little Narragansett Bay, Stonington: 343 acres

• Niantic Bay: 212 acres

• Mystic Harbor: 162 acres

• Goshen Cove, Waterford: 124 acres

• Rocky Neck State Park, East Lyme: 103 acres

• Mumford Cove, Groton: 82 acres

• Stonington Harbor: 58 acres

• Jordan Cove, Waterford: 38 acres

• New London Harbor, 34 acres

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