In 2000, NOAA planted 500 square meters of cordgrass and added oyster shell on Pivers Island; the living shoreline later weathered Hurricanes Irene and Florence

Two decades ago, a strip of beach outside NOAA's marine lab in Beaufort, North Carolina, was slowly disappearing into the water. According to NOAA's Habitat Blueprint page on the living shoreline at Pivers Island, the sandy beach experienced significant erosion during the late 1990s. At that time, the usual fix for the problem would have been either a seawall or a rock revetment. In March 2000, NOAA researchers planted roughly 500 square meters of local cordgrass, Spartina alterniflora, and placed an oyster shell sill at the waterline instead of a granite sill or seawall. It was a test of whether a living shoreline could perform as well as a hardened one.

A greener alternative to concrete walls

Living shorelines are not the same as seawalls. Unlike seawalls, which use concrete barriers to block waves, living shorelines use marsh grass roots to hold soil in place, while an oyster-shell barrier just offshore helps reduce wave energy. The project's construction didn't stop with the initial planting: additional oyster shell was added in the summers of 2000, 2006, and 2007, placed below the marsh's lowest point and along the outer margin of the mud flats so it would not sink into soft sediments. The project was carried out by NOAA and Duke University staff and volunteers, with oyster shell provided and placed by the North Carolina Division of Marine Fisheries. Ultimately, sediment deposition helped the marsh expand seaward, and erosion of the adjacent lawn stopped.

A first real test: Hurricane Irene

The shoreline's first major challenge came in 2011 when Hurricane Irene struck the North Carolina coast. A NOAA report titled 'Impact of Hurricane Irene on Pivers Island Shorelines' found that shorelines stabilized with natural vegetation, including the Pivers Island marsh, showed no eroding effect on the marsh surface during the hurricane. Sections near man-made structures like seawalls, however, fared poorly. This first outcome gave scientists hope that the living shoreline could survive more than routine tides and everyday wear.

Hurricane Florence puts it to the ultimate test

An even bigger challenge arrived in September 2018, when Hurricane Florence struck eastern North Carolina as a Category 1 storm, creating a storm surge of two to five feet, as well as maximum sustained winds of around 75 mph from the northeast. What made Florence so brutal was how long it stuck around. The coastal region endured tropical storm-force winds for almost 72 hours straight, much longer than a typical hurricane lasts. Photos taken nine days after the hurricane and published on the NOAA project website show that the living shoreline remained intact, with only light erosion in a few unplanted spots on the landward side. Eighteen years after it was planted, the living shoreline appeared more resistant than the man-made structures it was meant to replace.

More than a storm barrier

Beyond resisting hurricanes, the marsh's roots retain sediment, which can otherwise cloud the water, improving water quality in the estuary, according to NOAA's project summary. The oyster reef also grew taller over time and now helps create habitat for fish and birds alongside the marsh. There's a carbon angle too: in the 2015 PLOS ONE study "Living Shorelines: Coastal Resilience with a Blue Carbon Benefit," NOAA researcher Jenny Davis and colleagues measured carbon sequestration on similar living shorelines in North Carolina ranging from 58 to 283 grams of carbon per square meter annually, with higher rates in younger marshes. The study notes that marsh age is therefore an important factor in estimating how much carbon any single living shoreline can store over time.

Why a small beach in North Carolina matters

Pivers Island is barely more than a sandy strip of land, but its long-running record offers a useful case study for anyone deciding how to defend a coast against the encroaching ocean. With rising sea levels and stronger storms in many places, more communities are weighing a concrete barrier against a green shoreline. What the Pivers Island project shows is that a grass-and-shell shoreline held up through two hurricanes seven years apart, while also filtering water, sheltering wildlife, and storing carbon along the way.