URI researcher: Eelgrass on decline in Rhode Island waters

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Shallow eelgrass bed. Courtesy: NOAA

KINGSTON, R.I. – July 17, 2017 – Michael Bradley calls eelgrass “the canary in the coal mine for estuarine health.” The flowering plant that grows beneath the surface of coastal waters and salt ponds provides nursery habitat for shellfish and finfish while also dampening wave energy, stabilizing sediments and serving as an indicator of clean water.

But according to a recently issued report by the University of Rhode Island’s Environmental Data Center, eelgrass in Rhode Island is declining in Narragansett Bay and in most of the state’s coastal salt ponds.

The report found 1,144 acres of eelgrass and other submerged vegetation in state waters, an 18 percent decrease from 2012. The largest declines occurred in Quonochontaug Pond (52 percent), Point Judith Pond (48 percent) and Little Narragansett Bay (25 percent).

More than half of the state’s eelgrass occurs around Jamestown, which experienced a 19 percent decrease in eelgrass acreage. Ninigret Pond was the only coastal pond not to have a decrease, and the Narrow River was the only site that experienced a significant increase (45 percent) since 2012.

“It’s difficult to know exactly what’s going on,” said Bradley, a URI research associate and lead author of the report. “The reasons can be varied. An increase in water temperature could have something to do with it. Pollution in the water or soil could have something to do with it. And severe storms like Hurricane Sandy could certainly affect it. We need more surveys, more data and more analyses to get a better handle on what is determining eelgrass changes.”

Eelgrass beds can also be degraded by algal blooms or disease or be physically damaged by human activities like shallow-water boating, dredging, and construction of docks and other structures.

Data for the report was collected by aerial surveys funded by the Rhode Island Coastal Resources Management Council.

Bradley said that the decline in eelgrass is worrisome. “If you care about shellfish, if you like to have scallops, if you care about commercial or recreational fishing, then you should care about eelgrass,” he said. “The bottom line is that’s where the little critters go to hide to become big critters that can become commercially or recreationally available.”