Estuarine Shoreline Management Research Needs
This list is a composite of research and monitoring priorities identified by an ad-hoc workgroup consisting of staff within the Regulatory, Policy, and Coastal Reserve sections of the Division of Coastal Management. The list of priorities is organized into three broad topical areas (in no order of importance). The list is not intended to be exhaustive, rather a ‘living document’ depicting current priorities identified by workgroup members. Please direct inquiries and questions regarding this list to the Coastal Reserve's Research Coordinator, the Coastal Reserve’s Research Coordinator. Please also view the Divisions of Coastal Management & Marine Fisheries Living Shorelines Strategy Report and Living Shorelines Accomplishments Report.
Impacts of shoreline stabilization approaches on emergent and submerged vegetation
- Is loss of emergent and submerged vegetation waterward of bulkheads, riprap, and sills occurring at rates exceeding loss where shorelines are not hardened?
- How are impacts of shoreline stabilization on emergent and submerged vegetation affected by sediment supply, energy regime, and/or other interacting factors?
- What are the environmental settings and site conditions where traditional bulkheads and rip-rap/revetments are harmful to intertidal and subtidal zones?
- When constructing marsh sills, what are the consequences of converting subtidal to intertidal habitat and existing soft-bottom intertidal habitat to hardened intertidal habitat?
- How does the performance of living shorelines change over time (i.e., as structures age)? Is intertidal habitat converted to upland habitat?
- How does different shoreline stabilization material perform in various environmental settings?
- What is the durability of oyster shell vs. rock vs. other alternative shoreline stabilization materials?
- What are the ecosystem benefits and tradeoffs of oyster shell vs. rock vs. other alternative shoreline stabilization materials?
- Are there site suitability differences across alternative materials (e.g., loose oyster shell, rock)? What are optimum conditions for each?
- What metrics should be monitored to determine success or failure across material types?
In April 2011, the N.C. Division of Coastal Management completed a project to evaluate the marsh sill projects that have been permitted in the state. We hope that this process will help us gain a consensus on the use of these structures in North Carolina. In order to do so, we are asking various agencies to help with this evaluation (the Divisions of Marine Fisheries and Water Quality, Wildlife Resources Commission, US Army Corps of Engineers, National Marine Fisheries Service, and US Fish & Wildlife Service).
Bulkheads are the predominant shoreline stabilization method used in North Carolina along estuarine shorelines. However, bulkheads have the potential to cause deleterious impacts to coastal marshes that provide many useful ecosystem services. While there are alternatives to bulkheads that provide similar levels of erosion protection and minimize the impacts to coastal marshes, in North Carolina these alternatives are underutilized by estuarine property owners and marine contractors.
In 2009 the North Carolina National Estuarine Research Reserve and the NOAA Center for Coastal Fisheries and Habitat Research initiated a project entitled, Sustainable estuarine shoreline stabilization: Research, education, and public policy in North Carolina. This research will increase understanding of the environmental and economic tradeoffs of alternative estuarine erosion control measures.
For more information, read the final report: Sustainable Estuarine Shoreline Stabilization: Research, Education and Public Policy in North Carolina
As development near coastal and estuarine ecosystems increases, so does the frequency of shoreline stabilization by property owners and industry. Shoreline hardening refers to a type of shoreline stabilization that uses materials like concrete, metal, wood, or rocks to protect a shoreline from erosion. The collective increase in hardening techniques can result in a loss of North Carolina's estuarine habitats, which is why it is important to inform property owners about softer, or natural, techniques that not only reduce erosion, but also improve habitat.
An alternative to shoreline hardening projects are living shorelines. Living shorelines prevent erosion through strategic placement of natural substances such as vegetation and oysters. Living shorelines help with stabilization by buffering wave energy and trapping sediments, which increases shoreline elevation. They also improve the overall health of coastal and estuarine ecosystems by providing nursery and foraging habitat for marine organisms and shorebirds, and improve water quality by filtering out pollutants.
The two projects featured below investigate the effects different shoreline stabilization methods have on habitat function, shoreline erosion and sedimentation, and the structural integrity of stabilization methods after intense storms.
In 2012, researchers at the University of North Carolina-Chapel Hill Institute of Marine Sciences (UNC IMS) published a study titled Fisheries Habitat Impacts of Marsh Sills (Living Shorelines) as a Shoreline Stabilization/Restoration Alternative to Bulkheads. . The project focused on the effectiveness of marsh sills on maintaining and restoring coastal habitats for fish and crustaceans. To accomplish this, the researches compared biodiversity and habitat use in marsh sills, bulkheads, and natural marshes. Results indicate that marsh sill sites serve as an additional refuge from predators for juvenile fish and crustaceans, provide new hard substrate for oysters and other organisms, and may serve a similar function as intertidal oyster reefs (Peterson and Bruno, 2012).
In 2014, a second study, assessed the damage to stabilizing structures after Hurricane Irene. Out of the structures assessed (sills, riprap, hybrid riprap/bulkhead, and bulkheads), only bulkheads showed visual damage after the storm. Stabilization methods were compared to gain better insight into which methods enhance resource availability, maintain shoreline integrity, and are cost effective. The findings in this study can be used by policy makers developing policies for coastal management of estuarine shorelines and the ecosystem services they provide (Gittman et al., 2014).