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Extent of Eelgrass in Narragansett Bay and Block Island measured in first mapping effort in 10 years

PROVIDENCE (January 14, 2008) – Save The Bay, the Department of Environmental Management’s Narragansett Bay Research Reserve, and the University of Rhode Island’s Environmental Data Center announce the issuance of a final report and atlas identifying the distribution and extent of eelgrass in Narragansett Bay. The report is the most comprehensive Bay-wide assessment since 1996 and provides vital data for statewide planning and restoration efforts.

 The report identifies 290 acres of eelgrass distributed throughout lower Narragansett Bay, as well as 114 acres along the south shore of Newport and Little Compton. The largest eelgrass bed, at 63 acres, is located at the Sakonnet Lighthouse. Approximately 61 acres of eelgrass were also mapped around Block Island. This total reflects an increase of approximately 100 acres since the last mapping effort, in 1996. However, this increase may be attributed both to better mapping technology and ground verification methods, as well as eelgrass expansion in some areas.

“Mapping the extent and distribution of eelgrass beds provides essential information for town planners, government agencies, and the scientific community involved in Bay restoration and management efforts,” says Robert Stankelis, manager of DEM’s Narragansett Bay Research Reserve on Prudence Island. “It is widely recognized that healthy eelgrass beds are a good indicator of an estuary’s overall ecological health. Eelgrass beds are an important source of food and shelter for a variety of marine life, including economically important finfish and shellfish species such as the bay scallop. Changes in the distribution of eelgrass beds over time can help inform coastal managers how policy decisions may be affecting the health of the Bay.”

Results obtained required a multi-step verification process. First, aerial photographs collected in 2006 were analyzed by the URI Environmental Data Center to identify and delineate eelgrass bed locations. The accuracy of these interpreted beds were then field-verified by scientists and volunteers. Final delineations of the deep-water edges of the beds were determined using underwater video equipment. The process provided data to allow for accurate assessment of eelgrass change in the future.

“Historically, the distribution of eelgrass in the Bay was far wider than it is today indicating a great potential for restoration” says Save The Bay Executive Director Curt Spalding. “For example, as recently as the 1920s, much of Greenwich Bay was occupied by eelgrass beds compared with none today. Currently, many areas of the Bay are inhospitable for eelgrass growth, because of poor water quality. This is largely due to excess nutrient loading from wastewater treatment facilities, coastal septic systems and fertilizer runoff from lawns. Future improvements in water quality may lead to eelgrass expansion.”

Download the full report.

Funding for the $96,000 project project was provided by the RI Habitat Restoration Trust Fund, the Estuarine Reserves Division of the National Oceanic and Atmospheric Administration, the Natural Resources Conservation Service, a partnership between NOAA Fisheries Restoration Center and Restore America's Estuaries, and the Town of New Shoreham. Additional project partners include DEM’s Division of Fish and Wildlife, the Rhode Island Natural History Survey, and the Narragansett Bay Estuary Program.

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