North Carolina
National Estuarine Research Reserve
Technical Paper Series • Number 5
Estuarine shorelines are at risk of erosion from
several sources, including wave action, wind
scouring and boat wake. Many property own-ers
look to shoreline stabilization structures to
decrease or stop erosion of their land. Stabili-zation
structures can also provide protection
during storm surges and hurricanes. But did you
know that some stabilization structures can have
conservation benefits as well? Such structures
are called ‘living shorelines’ because they also are
designed to provide natural habitat and preserve
the ecological functions of the estuarine marsh.
In North Carolina estuaries, creating a living
shoreline may be as simple as planting native
marsh vegetation like smooth cordgrass (Spartina
alterniflora) along a compromised bank. In low
energy environments, the cordgrass roots and
stems are enough to trap
and hold sediment.
In areas with more wave
energy, additional con-struction
may be required.
Hard materials like rock,
oyster shells or marl may be
incorporated into the living
shoreline design. A gently
sloping, reinforced shore-line
provides a large surface
area for wave energy to dis-sipate,
as well as additional
habitat for plants and animals. This design also
allows terrestrial wildlife access to the water.
Some living shorelines called sills include
offshore mounds also built of rock, oyster shells
or marl. Sills are designed to break up waves
before they hit the shoreline and they may have
the added benefit of creating habitat for aquatic
organisms. One animal that often benefits from
this type of a living shoreline is the oyster. New
oyster reefs build up on sills because the larvae
settle on hard substrate. Fish use sills for shelter
and foraging.
Living shorelines serve as effective buffers to
protect shoreline property from erosion, while
simultaneously maintaining functional habitats
in the estuary.
Living Shorelines
The North Carolina National Estuarine Research Reserve is a cooperative program between
the North Carolina Department of Environment and Natural Resources, Division of Coastal
Management and the National Oceanic and Atmospheric Administration.
N.C. National Estuarine Research Reserve
101 Pivers Island Road • Beaufort, NC 28557
(252) 838 - 0883
www.nccoastalreserve.net
LIVING ALTERNATIVES
Below are three types of estuarine shoreline stabilization structures. Included are drawings of how each struc-ture
is built and a photograph of an existing structure. The first two alternatives are living shorelines. You can
see that natural vegetation and marsh habitat are included in the designs. In contrast, bulkheads generally do
a poorer job of supporting natural marsh functions.
BULKHEADS or SEAWALLS are
hard, vertical structures and are a common
shoreline stabilization structure. Because
they reflect, rather than absorb, much
incoming wave energy, scouring of adjacent
sediment can occur. Reflected wave energy
may not allow marsh vegetation and aquatic
organisms to thrive in front of bulkheads.
Bulkheads may reduce the amount of sedi-ment
and nutrients flowing into the marsh.
SILLS made of rock or oyster shells are
placed just off the shoreline to break up wave
energy. This allows vegetation to take root.
The sill may provide habitat for aquatic organ-isms
like algae, shellfish, crustaceans and fish.
Sediment can be added behind the sill and
planted with cordgrass, a native marsh plant.
The top of the sill usually extends just above
the high water mark.
REVETMENTS are sloped structures built
against the shoreline to absorb wave energy
and prevent erosion. Building materials in-clude
rock, concrete and oyster shells. These
structures are long lasting and can be com-bined
with marsh grass plantings. The riprap
provides habitat for some aquatic species.
Revetments should be placed as far landward
as possible to conserve the intertidal zone.