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Living shorelines are an ecological approach to erosion control - November 29, 2012

Whether you’re a visitor or a lifelong resident of the coastal bays, one thing is impossible not to notice: Where there is development on the water, the shoreline has been altered. In Ocean City it is most evident, but on almost every shoreline throughout the coastal bays, it is clear that wherever people have decided to stay, they have manipulated the shoreline to suit their needs. These changes range from simply clearing the area of trees, shrubs and grasses so they can have a better view of the water to much more complex and costly projects like installing docks, wharfs, seawalls or other man-made structures.

People have been using manmade structures for erosion control and shoreline use for centuries; the oldest known dock is more than 4,000 years old. While these practices were fine for civilizations in the past, with all the new knowledge and information we have available, we can create a much more natural and effective area of erosion control. Manmade structures such as seawalls, bulkheads and revetments destroy habitat for many animals, are less resilient to sea level rise and storm action, and can create more erosion in the area they are built, or areas close by, due to tidal energy being reflected instead of absorbed. The best way to create a more natural and efficient shoreline is to create a “living shoreline.” Living shorelines are very different from manmade erosion control techniques, as the main emphasis is using the natural hydrology of the area to install indigenous plants, both aquatic and terrestrial, along with sand and nonaltered stones.

The fundamental concept behind living shorelines is a reliance on natural methods that do not sever existing connections between riparian, intertidal, estuarine and aquatic areas essential for water quality, ecosystem services and habitat values. Living shorelines provide far more benefits than manmade structures, such as stabilizing shorelines, protecting the wetlands behind them, absorbing tidal and storm energy, allowing for the movement of wetlands upland to account for sea level rise, improving the water quality via filtration of runoff and creating vital habitat for both aquatic and terrestrial species for many animals, including endangered animals such as the Diamondback Terrapin.

Living shorelines replace manmade structures with a much more natural shoreline area — to the untrained eye it can look like a natural wetland that has not been changed at all. The structure of the living shoreline is simple. A few feet off the actual shoreline, a living breakwater is placed — loose stones and rocks that provide habitat for many marine invertebrates. Coming closer to shore, you find submerged aquatic vegetation and artificial oyster reefs. These help filter the run off and provide excellent habitat for many estuarine species, including our blue crab.

Coming onto the shore itself, the next areas are flooded areas, either regularly or irregularly, and are built up using sand and silt. Native marsh plants are planted here to help stabilize the sand and control erosion as well as help absorb excess nutrients from upland run off. These areas are crucial because they help absorb much of the tidal energy coming into the shoreline and create habitat for animals, including shorebirds, such as the seaside sparrow. Last are the more upland areas that rarely get flooded, including the bank face and upland buffer areas. These areas contain the deep rooted shrubs and trees which help stabilize the upland area and provides a space for the marsh to migrate into due to sea level rise.

Erosion control and water quality go hand in hand when it comes to the marine ecosystem. The more erosion in a certain area, the higher the turbidity and suspended particles in the water column, which in turn reduces visibility that harms the health of submerged aquatic vegetation and benthic organisms such as oysters and clams that help clean the water column and ultimately results in a reduction of water quality. By adding many different plant species, from upland trees and shrubs to aquatic vegetation, living shorelines not only help increase the productivity and diversity of areas once having only manmade structures, they also help absorb excess nutrients like nitrogen and phosphorous that run off from the upland areas. They help keep fine, loose sediments in the marsh area and out of the water column.

Another major benefit of living shorelines is their ability to absorb tidal and storm energy that would normally crash into manmade shorelines and damage structures along the coast. When large waves created by storms crash into manmade structures such as seawalls, the energy is reflected off and sent elsewhere. Often it can be multiplied, thanks to the reflection and refraction of waves. In our coastal bays,where the area between shoreline to shoreline can be small, this can have a devastating effect where wave and tidal energy bounce back and forth and ultimately do more damage than they would have initially.

In a living shoreline, much of this energy can be absorbed without little to the marsh. Ultimately it is much cheaper to replant some grasses than to reconstruct a whole dock or bulkhead.


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