Sand Dunes: Their Ecological Importance

Sand dunes are of tremendous ecological importance. They create habitat for plants and animals, provide shelter from wind and water, and protect our beaches and shorelines from erosion. They also shield lagoons and estuaries and can help safeguard against storm surge flooding and rising sea-levels.¹

Kouchibouguac National Park is home to 25 km of sand dunes that make up barrier islands resting in the Northumberland Straight. In this post, I talk about sand dunes and their importance using Kouchibouguac as an example.

Sand Dunes

Sand dunes are created by wind and waves and held together by plant roots and rhizomes. They form when sand starts to pile up against an object like “seaweed, a rock or a piece of driftwood.”² Over time, the sand pile grows large enough that plants can begin to grow.

According to Parks Canada, as the “pile of sand gets bigger…it doesn’t take long before marram grass can colonize the beginnings of the dune. Marram grass is the most important plant on a sand dune. It spreads quickly by its specialized roots, called rhizomes, that grow not only down but sideways and through the sand. These rhizomes form a network that helps hold the sand dune in place.”³

Sand dunes are fragile and regularly exposed to harsh weather, waves, and tides. Because of this, they are constantly changing shape and composition. Drastic changes take place over longer periods of time or during extreme weather, but short-term seasonal changes also happen.

In Kouchibouguac, sediment analysis has shown that the composition of dunes changes seasonally.⁴ Researchers determined that “an interplay of wind and wave processes on the sands…is constantly mixing beach, dune and lagoon sands.”⁵ In the summertime, southwest winds “cause most of the beach and dune sands to take on the characteristics of wind affected sands while the fall and spring storms impart characteristics of wave deposition to the beach sands.”⁶

Lagoons

Lagoons “are shallow bodies of water separated from the ocean by sandbars, barrier islands, or coral reefs.”⁷ They play a vital role “in supporting human well-being because of their immense biological resources and the life-supporting services they provide.”⁸

Lagoons “provide safe refuges as nurseries and feeding grounds for many commercially important species such as shellfish and finfish.”⁹ In Kouchibouguac, lagoons make up 5 percent of the park.¹⁰ Park staff refer to the lagoons as park “nurseries^“ because several fish species, including striped bass, use them as spawning grounds.¹¹

Lagoons also provide hiding places for animals. Eel grass (Zostera marina) which grows in Kouchibouguac’s lagoons, provides excellent shelter for smaller fish like stickleback, silverside, mummychog, and flounder.¹² Hermit crabs, rock crabs, and lobster also take refuge in the lagoons.¹³

Salt Marshes

Salt marshes make up 2.6 percent of the total surface area of Kouchibouguac National Park.¹⁴ These marshes are sheltered by dunes and, like lagoons, they provide habitat, food, and hiding places for animals.¹⁵

Salt marshes provide important nutrients to a surrounding ecosystem. “Tides carry in nutrients that stimulate plant growth in the marsh and carry out organic material that feeds fish and other coastal organisms. Over time, salt marshes accumulate organic material, forming into a dense layer called peat.”¹⁶

Flora

Plants that live on sand dunes have to tolerate disturbed soils, wind, water, and salt spray. The most prominent plant that makes up Kouchibouguac’s sand dunes is marram grass (Ammophila arenaria).¹⁷ That said, “older and lower dunes” located near lagoons also “support mosses and some wild rose shrubbery.”¹⁸

Marram grass is a xerophyte, a plant that has adapted to withstand arid conditions.¹⁹ It works so well as a dune stabilizer that conservation groups and parks on the Atlantic Coast use it for coastal stabilization.²⁰

Another noteworthy plant found around Kouchibouguac’s dunes is St. Lawrence Aster (Symphyotrichum laurentianum). St. Lawrence aster lives in “coastal habitats such as, lagoon shores, dune slacks and dry stretches of salt marshes.”²¹ This endangered plant was wiped out of Kouchibouguac by storms in the early 2000s.²² But, in 2016, a project began to reintroduce the species and now a self-sustaining population exists.²³

Fauna

Many animals rely on sand dunes, lagoons, and salt marshes for habitat, food, and breeding grounds.

Kouchibouguac is an Important Bird Area.²⁴ Its sand dunes attract the “largest common tern colony in eastern Canada and the second largest along the North American seaboard.”²⁵ Common terns (Sterna hirundo) were almost extirpated from the Atlantic Coast in the late-1800s, but conservation efforts were successful and these birds are no longer endangered.

The park is also home to the endangered piping plover (Charadrius melodus). Plovers nest on “wide sandy beaches with little vegetation and a mix of substrates such as pebbles, gravel, shells and sticks.”²⁶ Parks Canada has partnered with Nature NB and Environment and Climate Change Canada to protect remaining plover populations. In Kouchibouguac, their breeding grounds are off limits to human traffic.

In addition to birds, clams, blue mussels, periwinkles, oysters, crab, lobster, alewife, striped bass, Atlantic salmon, trout, smelt, tomcod, flounder, eel, gaspereau, stickleback, mummychog, silversides, jellyfish, moon snails, and other fauna are found. They all rely on an ecosystem supported by sand dunes.

Threats to Dunes

Sarah Robinson summarizes the biggest threats to sand dunes as, “recreational vehicle and human traffic, coastal development, and exotic species invasions.”²⁷ Invasive species “threaten dune ecosystem integrity, rare species habitat, and associated biodiversity values.”²⁸

In addition to these threats climate change is also “expected to strongly influence dune values in New Brunswick. Rising water levels and storm surges, associated with shifting weather patterns, will shape the ecology, geomorphology, and extent of provincial dunes.”²⁹

Protection of Dunes

Parks Canada is working to protect Atlantic Canada’s coastal dunes. They’ve closed off some areas to visitors and installed boardwalks so people don’t have to walk on dunes to get to beaches.³⁰ Park staff and volunteers plant marram grass to help stabilize damaged dunes.³¹ They also work to educate people about the fragility and importance of dunes.³²

There are things you can do as well! If you ever visit sand dunes, stay on the beach and off the dunes. “It takes only ten footsteps to kill a marram grass plant.”³³ You can help teach friends and family about sand dunes and their importance for the surrounding ecosystem. You might even be able to volunteer in local dune restoration projects.

Visit Kouchibouguac National Park’s Sand Dunes

You can see Kouchibouguac’s sand dunes for yourself at Kelly’s Beach. To get to the beach, you’ll take a 1.2 kilometre boardwalk over salt marshes, lagoons, and dunes. There are interpretative signs throughout the boardwalk to teach you about the area.

To learn more about salt marshes, check out Salt Marsh Trail. It’s a short (0.9 km) interpretative trail. You can also attend “Lagoon Life,” a guided tour that has you looking for lagoon inhabitants with dip nets. The tour is offered in both English and French.

Another way to experience the area is by paddling. Kayak and canoe rentals are available at Ryan’s Equipment Rental.

Other Resources

Thinking about camping at Kouchibouguac National Park? Check out my post: Backcountry Camping in Kouchibouguac National Park.

You can get an idea of the scale and geography of the dunes in Kouchibouguac National Park using this map.

Article Sources

Hogan, Jessica. 2018. “Understanding ATV Use: Perceptions of Impact and Actual Impact on Dune Systems in New Brunswick, Canada.” URL.

Parks Canada. 2013. “Sand Dunes” Eco-lessons from the National Parks in Atlantic Canada.” URL.

Bryant, Edward Arnot. 1972. “The Barrier Islands of Kouchibouguac Bay, New Brunswick.” URL.

Evers, Jeannie and Caryl-Sue. 2011. “Lagoons.” National Geographic. URL.

Miththapala, Sriyanie. 2013. “Lagoons and Estuaries: Coastal Ecosystems Series.” Mangroves for the Future: Investing in Coastal Ecosystems. URL.

NB Tourism. 2009. “Kouchibouguac National Park: New Brunswick, Canada.” URL.

Robinson, Sarah. 2010. “Coastal Sand Dunes of New Brunswick: A Biodiversity and Conservation Status Assessment.” URL.

Parks Canada. 2020. “Kouchibouguac National Park: Piping Plover Recovery.” URL.

Ross, Cindy. “Dunes of Kouchibouguac: Family Paddling with Common Terns and Grey Seals.” URL.

Important Bird Areas Canada. “Kouchibouguac NP Sand Islands.” URL.

Parks Canada. 2020. “Kouchibouguac National Park: Gulf of St. Lawrence Aster Restoration.” URL.

Doria-Brown, Jessica. “Island Nature Trust Takes ‘Softer’ Approach to Dune Preservation.” CBC. URL.

New Hampshire Department of Environmental Services. 2004. “Environmental Fact Sheet: Functions and Values of a Salt Marsh.” URL.

Vancouver Aquarium. 2012. “The Importance of Salt Marshes.” URL.

Leblanc, S. and L. Vasseur, David Mazerolle, and Eric Tremblay. 2003. “Changes in Plant Communities in Salt Marshes of Kouchibouguac National Park of Canada.” URL.

Patriguin, D.G. and C.R. Butler. 1976. “Marine Resources of Kouchibouguac National Park.” URL.

Parks Canada. 2010. “Kouchibouguac National Park Management Plan.” URL.