Managing for Biodiversity and Blue Carbon in the Face of Sea-level Rise and Barrier Island Migration

Principal Investigator:

Keryn Gedan

Start/End Year:

2016 - 2018


George Washington University

Co-Principal Investigator:

Chris Hein, Virginia Institute of Marine Science; Sunny Jardine, University of Delaware, School of Marine Science and Policy; Jorge Lorenzo Trueba, Montclair State University, Earth and Environmental Studies

Strategic focus area:

Resilient ecosystem processes and responses


Barrier islands serve as buffers between the coastal ocean and mainland agricultural lands, human population centers, and infrastructure and protect these investments from devastating storm impacts. The marshes, bays, lagoons and tidal flats behind these barriers support a high degree of biodiversity and also provide other ecosystem services including blue carbon storage. The proposed research focuses on the geologic and ecologic response of coupled barrier-backbarrier systems to relative sea-level rise and the implications for the backbarrier ecosystem services of biodiversity provision and blue carbon sequestration. Field geologic and ecologic data from barrier systems diverse in their migration rates and degree of anthropogenic stabilization and development (Parramore and Assawoman islands in Virginia; Fenwick/Assateague Island in Maryland / Delaware; Long Beach Island in New Jersey) will be used to calibrate a numerical morphodynamic model that will then be widely applicable to understanding barrier system response (in terms of migration rate and backbarrier dynamics) to variable sea-level rise rates and anthropogenic stabilization measures. Morphodynamic model outcomes will be iteratively coupled with a human-behavior (economic) model to provide insight into the best-practices for designing optimal barrier stabilization and marsh conservation and restoration programs which consider the net benefits from protecting blue carbon stocks, biodiversity, and beach width in a wide range of settings. Relative sea-level rise and management scenarios will be derived through literature reviews and consultations with four primary outreach partners (the Accomack-Northampton Planning District Commission / Climate Adaptation Working Group [VA]; Assateague State Park [MD]; the Center for the Inland Bays [DE]; and the Jacques Cousteau National Estuarine Research Reserve [NJ]), who will serve as points of contact to the broader management, conservation, and decision-making communities in these four states. This project will support the training of three PhD students and four undergraduate students. It will result in: (1) the publication of four disciplinary scientific articles and 2–3 interdisciplinary scientific articles; (2) one publically available white paper on best practices for barrier systems management for blue carbon and biodiversity based on iterative morphodynamic and human behavior model simulations which will be made available through Sea Grant and partner organizations; and (3) a series of two Coastal Change Workshops held in December 2017 to January 2018 with potential audiences of > 100 coastal managers, conservation agents, decision-makers, etc. from New Jersey and the Delmarva Peninsula, respectively.


RelevanceSea level rates in the Chesapeake and coastal bays are rising at about twice the national average. Climate change is making storms more intense. This combination is changing barrier islands, which serve as a protective buffer between land and sea and support a tremendous amount of biodiversity and economic activities on the islands themselves and in calm back-barrier waters. To keep the sands from constantly shifting, some barrier islands are nourished with new sand. Typically, barrier islands are managed to protect island property and promote tourism, rather than preserve their role in storing carbon and providing for biodiversity in back-barrier marshes and lagoons. But researchers weren't sure if the islands could continue to serve as a carbon sink in the face of sea level rise, more frequent over-washing, and climate change.

ResponseResearchers in Washington, D.C. worked with partners in Virginia, Delaware, and New Jersey to examine barrier island migration and its effects on carbon sequestration and capture, as well as ecosystem services. Their goal was to develop a model to guide managers on what to expect in terms of barrier island migration and back-barrier change and how that will affect plant biodiversity and the marshes' role as a carbon sink. The model will provide insight on how best to safeguard biodiversity and conserve the carbon captured by these ecosystems, also known as blue carbon.

ResultsThese researchers are developing maps of carbon distribution in the back-barrier marshes and an understanding of how marsh carbon is expected to change with barrier island migration. Managers can use this information to decide whether it is wise to nourish barrier islands, given possible tradeoffs in back-barrier ecosystems services when the islands are prevented from migrating. The researcher briefed Congress on findings on how sea level rise changes landscapes and seascapes, and has met with wildlife refuge supervisors about how sea level rise affects the carbon sink on Assateague Island in Maryland, a major tourism destination.

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