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Saturday, December 29, 2012

Marshes critical to ecosystem

Marshes on U.S. Coast Need More Protection NOW
From: Roger Greenway, 

A hundred years ago we thought that we had to fill in the marshes near populated areas along the eastern US coastline since they represented prime locations for commercial and residential development. 

Even after some protections were put in place to reduce the impacts of runaway development, marshes continued to serve are the places we dumped our garbage, and sent the effluents from our wastewater treatment plants. 

They also receive the nutrient-rich run off from agricultural land use and urban street runoff to our rivers.

A major nine-year study led by researcher Linda Deegan points to the damage that human-caused nutrients inflict on salt marshes along the U.S. East Coast. In a Yale Environment 360 interview, she describes what these findings mean for an ecosystem that provides critical services, from nourishing marine life to buffering the coast from storms like Sandy.

For centuries now, the salt marshes along the U.S. coast have been disappearing, with some experts estimating that 70 percent have been lost, largely due to development. While in recent decades the U.S. has done a better job of protecting these ecosystems, even marshes spared from development are now succumbing to more subtle threats, from rising sea levels to invasive species.

One factor scientists always thought marshes could withstand was nutrient enrichment, such as the flow of nitrogen and phosphorus from fertilizers and septic systems. But that might not be so, warns Linda Deegan, a senior scientist at the Marine Biological Laboratory in Woods Hole, Mass., and lead researcher of a long-term study showing that an overabundance of nutrients may be contributing to the demise of salt marshes.

During the nine-year study, in which Deegan's team added nutrients to a Massachusetts estuary, the researchers found that a burst of growth eventually caused the salt marsh plants to collapse onto themselves, converting healthy systems into mud flats.

In an interview with Yale Environment 360 Web editor Kevin Dennehy, Deegan describes the implications of this study, the vital services lost when marshes disappear — from nourishing marine species to providing a physical barrier for coastal communities during storms such as Hurricane Sandy — and what it will take to prevent further marshland loss.

"What Sandy brought home is that trying to draw a line and say, 'From here on back is human lands, and from here forward is the natural system,' isn’t going to work," Deegan said.

Read Kevin Dennehy's interview with Prof. Deegan at Yale Environment 360.