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Vanishing marshes under assault from variety of sources

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Sea-level rise, invasive plants and development play role in creating stress

Wetlands and marshes are the last line of defense.

Not only do they provide habitats for fish, wildlife and plant life, they also provide an invaluable buffer between open water and land.

"They are at the front line, where the battle is won or lost," says Danielle Kreeger of the Partnership for the Delaware Estuary.

So far, the battle is being lost The Delaware Bay coast lost 22 percent of its wetlands between 1992 and 2001, and the trend is continuing as sea-level rise, development and storms continue to damage the coast The loss of marshes in Prime Hook and Bombay Hook national wildlife refuges threatens an already fragile coast and could forever change the ecology and landscape of the area.

Scientists predict sea-level rise and future storms threaten Prime Hook's 10,000 acres of marshland and uplands. As these factors nibble away at the coastline, it's more a question of when marshes will convert to open water, not if they will convert. Sea-level rise in the Delaware Bay over the next century could be as little as 1 meter or much as 3 meters, scientists say.

Prime Hook Refuge is unique, with saltwater as well as freshwater marshes, which are managed by a system of water-control devices.

"Man has fiddled with this property as much as any property in the USA," said Primehook Beach resident Sam Burke. "A lot of the problems are our own fault."

He said one of the main creeks in the refuge, with a drainage outlet to Delaware Bay, was blocked, and the water was diverted to Cedar Creek near Slaughter Beach. The other main outlet Primehook Creek,-was cut off by nature.

Burke said the water flowing into the Prime Hook marshes has to go somewhere and it ends up in the man-made impoundments. "The gates are not big enough to handle the flow of water," he said.

Burke agrees with refuge management that maintaining the freshwater marshes may not be feasible in the future. "They need to tear out the impoundments and let the water flow free," he said.

Marshes under stress

Wetlands and marshes are under stress in the Cape Region. Although they provide habitat for plants and animals, there also serve as a barrier that acts like a sponge to soak up water between open water and the land and provide flood control.

Wetlands are under assault from many sources: sea-level rise, development, invasive species such as phragmites, mosquito ditching and an overpopulation of snow geese, said Chris Bason, the science and technology coordinator for the Center for the Inland Bays (CIB).

The onslaught of pressure on marshes is actually decreasing uSeir size, he said. Bason, who spends a lot of his time standing in mud, said along with some degradation along the shoreline, he is beginning to see the collapse of wetland systems from within the interior as well.

Free-flowing water and flushing are critical to the health of marshes.

Bason said instead of flushing action, water is remaining stagnant in some marshes. That water logs the marsh, allowing salinity to increase, leading to release of hydrogen sulfide, and kills or stunts the growth of all-important marsh grasses, Bason said.

A recent report card issued by the Center for the Inland Bays gave the area's tidal wetlands a grade of D+. The wetlands near Prime Hook Refuge received a slighter higher grade of C in a report done by the Wetlands Assessment Section of the Department of Natural Resources and Environmental Control (DNREC).

Regardless of the current status, Bason said current science pointing to as much as a 3-foot rise in sea level over the next century would likely overwhelm the capacity of coastal marshes to keep up.

Bason said marshes tend to migrate over uplands, but factors such as sea-level rise and man-made shoreline structures like riprap and bulkheading impede that movement and lead to further erosion.

The center is beginning a study with the University of Delaware to better determine the status of Cape Region wetlands and how the stresses are affecting them.

Grasses are the foundation

The modification of the hydrology in areas in and around marshes and wetlands is also a factor in their destruction.

Amy Jacobs, a DNREC environmental scientist, said wetlands are disappearing at a significant rate. She said the past and current practices such as draining wetlands to create farmland has modified the hydrology of the area. "Essentially we have replumbed our landscape with significant impacts on wetland resources," she said.

Bason said many mosquito ditches are holding water and not draining as they were designed to do. This cuts down on the growth of grasses, which are essential to the life of a marsh.

The more natural the hydrology, the more water that drains and the healthier the marsh grasses are. Bason called the grasses the base of the wetlands ecosystem - a keystone species. "They are like trees in a forest," he said.

When grasses start dying off, the whole ecosystem is impaired.

Grasses trap sediment and when seasons change provide organic matter to help build up marshes. Bason said in a perfect ecosystem, marshes build up faster or at the same pace as the level of the sea. That is not occurring within Prime Hook Refuge; marsh growth is not keeping pace with sea-level rise.

Jacobs said most wedands are easily detected, but some wetlands are rarely wet; they are still important to the watershed. Some wetlands hold water as much as 12 inches below the surface and it only percolates to the surface during wet periods, as Sussex County is now experiencing.

People are building on wetland soils, which are supposed to be protected. Enforcement of the regulations is rare, she said.

"We all rely on wetlands, and they are disappearing before our eyes. If we don't do something it will end up affecting everyone," she said. "We need to take a step back and see what we have allowed to happen."

"WE ALL RELY ON WETLANDS, AND THEY ARE DISAPPEARING BEFORE OUR EYES. IF WE DON'T DO SOMETHING IT WILL END UP AFFECTING EVERYONE. WE NEED TO TAKE A STEP BACK AND SEE WHAT WE HAVE ALLOWED TO HAPPEN."

- AMY JACOBS,

DNREC ENVIRONMENTAL SCIENTIST





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