Coastal wetlands can adapt to rising oceans.

• Position: Tidal Marshes

Tidal marshes, which nurture marine life and reduce storm damage along many coastlines, should be able to adjust to rising sea levels and avoid being inundated and lost--if their vegetation is not damaged and their supplies of upstream sediment are not reduced, suggests a study by Duke University, Durham, N.C.

Such marshes "offer great value as buffers to coastal storms in cities such as New Orleans, which is separated from the Gulf of Mexico by marshlands," report A. Brad Murray, associate professor of geomorphology and coastal processes, and doctoral student Matthew Kirwan.

These coastal systems of water-tolerant plants and tidal channels "provide highly productive habitat and serve as nursery grounds for a large number of commercially important fin and shellfish," according to the researchers. Despite these benefits, a variety of environmental changes often linked to humans--including sealevel rise, sinking land, and alterations to sand and silt supplies that anchor wetland plants--are "affecting coastal marshes worldwide."

However, "if the vegetation is intact, it holds the system in place and enhances the trapping of sediments and tends to minimize the erosion," Murray points out. "Up to some high...