- The Washington Times - Tuesday, April 16, 2002

ANNAPOLIS Rising sea levels caused by global warming may erode the marshlands in the Chesapeake and Delaware bays by the end of the century, according to a study using satellite imagery.
If sea levels continue to rise at current rates or the higher rates predicted in climate models the two largest estuaries on the East Coast could disappear by 2100, the study said. Marshlands are spawning grounds and nurseries for saltwater fish, so the erosion has serious repercussions for fisheries.
"It's a significant problem," said Michael Kearney, a professor at the University of Maryland, College Park, who led the study. The study will appear in today's issue of Eos, a publication of the American Geophysical Union.
By 1993, about 70 percent of the marshes in the two estuaries showed damage from the rising waters, which could have devastating effects on the ecosystem, water quality and the amount of carbon released into the oceans and atmosphere.
Marshes act as sinks for carbon, holding it in solid form so it does not escape as carbon dioxide, a greenhouse gas. They also serve as filters, holding sediments and minerals that otherwise would muddy the Bay.
Mr. Kearney said the levels of marshland degradation are as bad as anywhere else on the Atlantic coast and rival that of the Mississippi Delta in Louisiana.
"It's about as bad as it can be," he said.
Bill Street, director of watershed restoration at the Chesapeake Bay Foundation, said the study provides "another example of how the Bay ecosystem is out of whack right now."
Mr. Street said the Bay is plagued with pollution and excessive nutrient runoff from farms and industry, leading to a depletion of sea grasses, which are key habitats for blue crabs and young fish.
"[The erosion] makes restoring the health of the Bay all the more difficult," Mr. Street said. He and others agree that stopping the rising waters is practically impossible, "so what we really need to do is address those issues that we can have some impact on."
That includes limiting pollution runoff, replanting underwater grasses and growing oyster beds.
Mr. Kearney's technique was based on 1993 images from a satellite, updated with more recent aerial photography and field surveys. The information is used to determine a Marsh Surface Condition Index, which tracks the overall health of the marsh.
The index helps scientists focus on the role of long-term sea-level rise, without regard to annual variations caused by heavy storms and other temporary phenomena.
On the Eastern Shore, the greatest erosion has occurred at Blackwater Wildlife Refuge. The upper reaches of the Chesapeake and the Delaware bays are less degraded than the middle and lower reaches.
From 1984 to 1993 in the Delaware Bay, the area of degraded marshes increased from 25 percent to 54 percent of the total marshland, especially on the New Jersey shore.
David Burke, director of the Chesapeake and Coastal Watershed Service at the Maryland Department of Natural Resources (DNR), said the rising waters and accompanying erosion also are chipping away at Maryland's coastline, including its barrier islands.
"That study was great and is sounding the alarm as it should be," Mr. Burke said.
The DNR is conducting studies to determine areas that are vulnerable to the rising seas, and it is doing what it can to stop the damage, such as building sea walls or bulkheads in places where waterfront homes, businesses and roads are in trouble. Mr. Burke says it is costly, so the DNR has to be selective.
One way to augment the marshlands is by spreading layers of sediments, sometimes spraying the silty material dredged up when channels are dug for ship traffic also an expensive process.

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