Rebuilding California Salt Marshes
Published on by Water Network Research, Official research team of The Water Network in Academic
Project rebuilds Elkhorn Slough salt marshes in California
Charlie Endris of Elkhorn Slough Reserve and Ivano Alello of Moss Landing Marine Labs have traced the transition of salt marsh habitat to mud. They used a geographic information system, or GIS, to trace changes relative to geographic location.
Marshes dominated the slough in the 1930s. A salty-tasting plant called “pickleweed” grew rampantly. Pickleweed roots held soil in place and helped the marshes retain their structure. But no longer.
“We’ve lost about 50 percent of the salt marshes to mud,” said Endris.
Kerstin Wasson, research coordinator at Elkhorn Slough Reserve, said people drained the wetlands to make farmland. When they did this, she explained, they caused the ground to dry, shrink and sink. Once marshes are too low, the pickleweed drowns, and little can prevent water from washing away soil. The marshes become mud.
Scientists say sunken marshes can’t offer habitat to wildlife or filter polluted water. Moreover, mud cannot suck greenhouse gases from the atmosphere and bury carbon in successive layers of soil — a service that marshes provide.
Marshes also avert disaster, according to Wasson. They buffer against stormy waves. If more salt marshes protected the East Coast, she said, “the effects of hurricane Sandy would not have been as strong.”
Now the reserve is heading a $6.5 million project to rebuild Elkhorn Slough’s marsh with mud dredged from the clogged Pajaro River.
“It’s like recycling,” said Wasson of the repurposed mud.
By piling mud just a few feet above water levels, the scientists say they can create an opportunity for the marshes to reestablish themselves in sturdy mounds that won’t wash away. Pickleweed will likely recolonize the marsh and further anchor the sediment.
Construction should end by 2017, according to project director Monique Fountain. Then scientists will monitor results.
Wasson said restoring the marsh helps everyone, human and otherwise. For example, the marsh shelters otters, which reel in tourists.
“Even if you don’t care environmentally,” Wasson said, “it’s a big economic engine in this region.”
Source: The Californian
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