Protecting & Restoring Long Island's Peconic Bays

Demonstration Living Shoreline Project

Learn about the benefits of living/ natural shoreline here and check out our progress on the Suffolk County Marine Environmental Learning Center Living Shoreline project in Southold.

Faced with rising sea levels and the potential for stronger, more frequent storms as a result of global climate change, many property owners on the east end of Long Island have been installing bulkheads, sea walls, and other hard shoreline structures to protect their property. Unfortunately, these hard structures can have negative consequences for the environment and wildlife, and can worsen coastal erosion and flooding, putting local properties at risk.

Hardened Shorelines

Graphic of hardened shoreline
Hardened shorelines reduce habitat and nursery grounds for native plants, fish, and wildlife, exasperate erosion, and lead to shoreline destabilization over time.

When hard shoreline structures are hit by waves, energy is reflected further down the shoreline disrupting natural sediment movement patterns and altering the shape of the coast. This process can alter the erosion and deposition patterns of sandy sediments, ultimately leading to shoreline destabilization. This destabilization can create problems for surrounding areas and may encourage nearby landowners to install hard structures along their property as well, further exacerbating the problem.

This “domino effect” of replacing natural shoreline with hard structures can result in the loss of important coastal habitats, including wetlands, beaches, and eelgrass beds. Habitat loss can negatively impact the fishing and tourism industries, as well as the wildlife that rely on these areas for feeding, reproduction, or nursery grounds.

Wave energy is reflected by hardened shorelines, leading to further shoreline destabilization.

Living shorelines absorb and dissipate wave energy and allow for natural water and sand movement patterns, preventing beach destabilization.

Graphic of current and sand movement

When waves hit the beach at an angle, sand is transported alongshore by wave energy. Waves also transport sand along the shore in a zig-zag pattern as they rush onto and off of the beach. This natural movement of sand is disrupted by hardened shorelines, which reflect wave energy and disrupt natural sand movement patterns, leading to erosion. Image taken from USGS.

Hard shoreline structures also cause other problems—they can leach toxins, such as copper, chromium, and arsenic, into the surrounding water, further impacting the ecosystem. Additionally, these barriers prevent the natural migration of marshes inland as sea level rises, leading to their loss instead of allowing for their adaptation. Loss of marsh habitat negatively impacts wildlife and plant populations, and makes Long Island more vulnerable to coastal flooding, erosion, and storm damage.

With continued sea level rise and a potential increase in storm frequency and intensity due to a changing climate, there is a growing demand for shoreline protection on Long Island. The impacts of hardened shorelines are well established. Developing alternative forms of shoreline protection that do not negatively impact our shorelines, while also providing benefits to our coastal ecosystem, is a priority for PEP.

Living Shorelines

Living shorelines provide habitat for native plants and wildlife while also providing many other benefits.

‘Living shorelines’ are a beneficial alternative to hardened shorelines. These ‘soft’ shorelines use native plants, shellfish, and other natural features such as rocks, sand, wood, coconut fiber, and shells to stabilize and protect coasts and decrease direct wave energy. Living shorelines are designed to mimic the natural environment and provide ecological benefits.

 

 

 

Benefits of Living Shorelines

Natural Sediment Movement

Allow for natural sediment movement patterns which will change a shoreline’s shape naturally without interference from a hard structure that can create unnatural alterations.

Shoreline Stabilization

Enhance stabilization of underlying sediment, native plants, and dunes by vegetation root systems.

Habitat and Nursery Grounds

Creation of habitat and nursery grounds for wildlife and native marsh plants, which in turn supports fisheries, recreation, and tourism.

Landward Migration of Coastal Habitats

Maintains or restores the connection between the coast and upland habitat that would otherwise be divided by a hard structure. This allows for the natural landward migration of coastal habitats as they adapt to rising seas, and also allows for the movement of wildlife that are dependent on access to coastal habitat for spawning or other aspects of their lifecycle.

Improved Water Quality

Natural or restored wetlands improve water quality by filtering excess nutrients and other pollutants from runoff as it passes over and through the marsh on its way to the estuary.

Reduced Flooding

Natural or restored wetlands can help reduce flooding through absorption, which is very important for low-elevation communities on eastern Long Island.

Carbon Sequestration

Salt marsh ecosystems are blue carbon systems, they sequester and store significant amounts of carbon from the atmosphere and surrounding water. According to NOAA, one square mile of salt marsh stores the carbon equivalent of 76,000 gallons of gas annually, helping to combat climate change.

Cost Effective Shoreline Protection

Often less expensive to install and maintain than hardened shoreline stabilization methods such as bulkheads.

Natural Shoreline Appearance

Provide an attractive, natural appearance, and allows for greater public access and viewing.

A comparison of living and hardened shorelines. Image from NOAA.

SCMELC Demonstration Living Shoreline Project in Southold

Faced with an increasing demand for shoreline protection among property owners, the Town of Southold wanted to provide its residents with an example of an environmentally-conscious alternative to shoreline hardening. For this reason, The Peconic Estuary Partnership  has been hard at work in collaboration with the Town of Southold, Suffolk County, and Cornell Cooperative Extension (CCE), with funding from the USEPA, The Suffolk County Water Quality Protection and Restoration Program, and the Town of Southold, to create a living shoreline demonstration at The Suffolk County Marine Environmental Learning Center (SCMELC) in Southold, New York. The project is anticipated to be complete in fall 2021.

Ribbed mussels clustered around Spartina shoots at the demonstration project site.

This living shoreline, installed along the banks of a creek at the SCMELC facility, incorporates several layers of shoreline stabilization as well as ribbed mussel (Geukensia demissa). A combination of cultured ribbed mussel and adult, transplanted ribbed mussel were used in the shoreline project. Transplanted ribbed mussel were collected from the existing population in this waterbody. Smooth cordgrass (Spartina alterniflora) seeds (from nearby marshes) were collected, propagated and raised in the CCE habitat restoration greenhouse prior to being planted.

This demonstration project also incorporates other natural structures to further stabilize the shoreline and provide a surface to which plant roots and mussels can attach. For example, bagged shell, rocks, coir logs, and wooden terracing are all included in the living shoreline project in order to test and demonstrate benefits, effectiveness, and appearances of each material in combination with the living features of the shoreline, Spartina grass and ribbed mussels.

Salt marsh edge showing ribbed mussel and cordgrass at CCE’s facility in Huntington, N.Y.

Ribbed Mussel (Geukensia demissa) Benefits in Living Shorelines

Increased Filtration of Nutrients, Pollutants, and Bacteria

Increased filtration of nutrients, pollutants, and dangerous bacteria. Ribbed mussels are one of the few shellfish species capable of foraging on small-sized bacteria and efficiently removing a wider range of particles and improving water quality.

Enhanced Growth of Marsh Plants

Research has shown that the presence of ribbed mussel increases the growth and survival of the smooth cordgrass by providing nutrients to the plant via deposition of feces.

Increased Primary Production

Help fuel primary production and the spreading of marsh plants by adding important nutrients to surrounding sediment, effectively “fertilizing” plant life.

Increased Habitat Complexity

Considered an “ecosystem engineer” species because they have the ability to build new and more complex habitats, providing more places for other coastal species to use for shelter from sunlight, heat, air, and predators.

Improved Salt Marsh Resilience

Contribute to salt marsh resilience by forming clusters that bind tightly to plant roots and other surfaces, building and strengthening the marsh to better resist erosion and storm damage.

Improved Adaptation to Rising Sea Level

As mussel densities increase, they help to trap and collect particles suspended in the water column, causing the marsh to increase in elevation. This allows the marsh to adapt its vertical growth to rising sea levels and better resist erosion.

Heightened Carbon Sequestration

Heightened carbon sequestration and storage compared to marshes without mussels.

Low Risk of Illegal Removal

This species is not considered edible; therefore, they are unlikely to be poached, or illegally removed from the marsh. This allows ribbed mussel to be placed in areas closed to shellfish harvest whereas other species such as clam or oyster are not allowed to be placed.

Living Shoreline Treatments

SCMELC Demonstration Living Shoreline

1. Rock Wall

Rocks, of varying sizes, are commonly used for shoreline protection. This particular location experiences minimal wave action therefore smaller sized rocks were used for sediment stabilization. This site demonstrates the appropriate use of small rock in place of a hardened structure or large boulder rock revetments.

2. Bagged Shell

Shell is a naturally occurring marine material that has been used extensively for creating underwater reefs and to protect shorelines from wave and storm energy. In this demonstration project, shell derived from oyster and clam was placed inside biodegradable mesh bags and stacked to create a wall-like barrier along the shoreline. Prior to being placed along the shoreline, shell was cleaned and baked in the sun for a year to reduce the risk of transferring any potential contaminants from where the shell originated.  Additionally, the calcium carbonate in shell may also help mitigate the impacts of ocean acidification by acting as a buffer to maintain a proper pH level for the waterbody.

3. Coir Log

Coir logs are commonly used for erosion control in shoreline projects. Consisting of interwoven coconut fibers encased in a natural, hemp net casing, coir logs are fully biodegradable and resilient; providing at least two years of stabilization before breaking down. Typically, this is enough time to establish a band of vegetation behind the logs, which will provide the erosion control once the coir logs have degraded.

4. Single Wood Terrace

Historically, natural wood terracing has been used to stabilize steep slopes. Terraces are created using short walls of wood to help absorb wave energy and hold a platform of sediment in place behind them. Unlike a conventional bulkhead, these shorter walls do not reflect wave energy, block landward migration of marshes, or cause the other issues associated with hardened shorelines. Instead, water is able to wash over each terrace and wave energy is absorbed while steep slopes are stabilized and protected from erosion. For this demonstration plot, a single-tier wooden terrace has been constructed from natural, native, and rot-resistant wood logs.

5. Double Wood Terrace

Historically, natural wood terracing has been used to stabilize steep slopes. Terraces are created using short walls of wood to help absorb wave energy and hold a platform of sediment in place behind them. Unlike a conventional bulkhead, these shorter walls do not reflect wave energy, block landward migration of marshes, or cause the other issues associated with hardened shorelines. Instead, water is able to wash over each terrace and wave energy is absorbed while steep slopes are stabilized and protected from erosion. For this demonstration plot, a single-tier wooden terrace has been constructed from natural, native, and rot-resistant wood logs.


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