Background

Natural marshes are nature’s ability to prevent erosion, clean the water, and create habitat by acting as a buffer between the sea and land. Land protection is provided by wave breakage and storm dampening because vegetation helps to decrease the impact of waves and storms. Marsh ecosystems also provide benefits for coastal waterways as the vegetation filters runoff and increases sediment retention before it reaches the water. Marshes are a great source of both primary and secondary production. Marshes host salt tolerant plant species that are an important source of organic matter. They also act as a habitat for many organisms. Marsh sediments are home to many benthic infauna species, and act as a nursery to nekton species and their prey. Humans benefit from the ecosystem services that are provided by marshes in many ways. Shoreline stabilization and protection is an ecosystem service because it protects human developments from flooding and destruction. The filtration of runoff provided by marshes makes the water cleaner and protects organisms and vegetation from nutrient loads that could be detrimental. Carbon sequestration is another ecosystem service provided by marshes, reducing the amount of carbon dioxide in the atmosphere.

Living shorelines are an alternative restoration method to combat the negative effect of erosion/hardened shorelines. Living shorelines are created from a natural marsh and commonly includes a hardened component, with the purpose of recreating ecosystem functioning like a natural marsh. One way living shorelines are created is by placing a hardened structure in front of planted native vegetation to act as a breakwater; but it can involve only planting, or addition of a hardened structure without vegetation. The vegetation can take root as the hardened structure provides erosion protection by dampening waves. Some restoration sites use biodegradable material for a more sustainable hardened structure while allowing the vegetation to take root. Living shorelines are a way of protecting the shoreline and maintaining the productivity of the ecosystem while meeting many desirable social priorities.

The goal of this research was to investigate the effects of different shoreline types (natural marsh, living shoreline, and hardened shoreline) on the physical (wave energy), geological (landscape and sediment), and biological (vegetation) conditions based on a case study from six representative sites. The objectives were to (1) collect and compare data on hydrographic features, including wave power and turbidity, among the three different shoreline types at six sites along a fetch exposure gradient, (2) determine geomorphic features including fetch distance, edge erosion rate and the resulting slope, and sediment composition for the shorelines at each of the six sites, and (3) determine abundance and diversity of the vegetation for the three different shoreline types and two energy groupings.