A recent NCCOS-funded study found that shoreline hardening, particularly riprap, has a negative effect on the abundance of submerged aquatic vegetation (SAV).Riprap, which is made up of rocks and boulders piled along the shoreline, is commonly used to prevent shoreline erosion, but once installed, alters the natural processes and composition of the land -sea interface.

The authors studied several sub-estuaries of Chesapeake Bay and identified a threshold value of 5.4 percent riprapped shoreline. In estuaries with less than 5.4 percent riprapped shoreline, SAV abundance increased over time, while in estuaries with more than 5.4 percent riprapped shoreline, SAV abundance did not increase over time.

SAV is an essential part of estuarine and marine ecosystems. SAV beds are habitats for juvenile fish, benthic crustaceans, and shellfish.SAV also takes up dissolved nutrients, provides oxygen to the water, and slows down water to settle sediments and reduce shoreline erosion.

An example of riprap. Credit: Maryland Department of Natural Resources.

Results of the study are expected to inform coastal managers' decisions about SAV restoration and the use of riprap. The findings are publishedin the journal Estuaries and Coasts and are highlighted in Coastal and Estuarine Science News, a newsletter for coastal management professionals.

For more information, contact Elizabeth.Turner@noaa.gov.