SYMP 4-6 - The loss and restoration of seagrass ecosystem services on the Virginia Eastern Shore

Tuesday, August 9, 2016: 10:40 AM
Grand Floridian Blrm B, Ft Lauderdale Convention Center
Matthew P. J. Oreska, Karen J. McGlathery and Lillian R. Aoki, Environmental Sciences, University of Virginia, Charlottesville, VA

Eelgrass (Zostera marina) meadows occurred in the outer coastal bays along the Virginia Eastern Shore until 1932, when the meadows disappeared during a North Atlantic eelgrass pandemic.  Most of the Virginia meadows failed to recover naturally, possibly due to seed limitation following the Hurricane of 1933.  The benthos in the coastal bays remained either bare or algal dominated for almost seven decades.  From 1999 to 2005, 70 million eelgrass seeds were broadcast over an approximately 2-km2 area.  By 2015, natural expansion had increased the restored meadow area to > 25 km2.  This success provides a rare opportunity to quantify restored eelgrass ecosystem services and benefits at the landscape scale, both in relation to historical services and benefits that were lost and to the costs of meadow restoration.  Net primary production, C and N sequestration, and sediment stabilization were quantified by measuring plant growth and biomass, C and N burial rates, and bed sediment grain size distributions, respectively.  Restored provisioning and cultural services were assessed using recent economic data.  Historical ecosystem services and benefits were identified from contemporary sources, including fishery statistics.  Lost supporting and regulating services were quantified according to observed stocks in the restored meadows and a range of estimates for former meadow areal extent. 


The restoration has yielded several significant ecosystem services, especially increased primary production and carbon sequestration.  The meadows produce an estimated 0.17 to 1.14 g biomass m-2 d-1 and bury Corg at a rate of approximately 37 g m-2 yr-1.  The mature meadow in South Bay has now accumulated approximately 195 t of sediment Corg km-2, providing a minimum estimate for the amount of Corg km-2 that was ultimately oxidized and released to the atmosphere after the original meadows disappeared.  However, the two most significant historical benefits of eelgrass have not yet fully recovered—the provisioning of commercially important bay scallops (Argopecten irradians) and brant (Branta bernicla)—due in part to ecological and economic changes since 1932.  A third historical service, fertilizer provisioning, has since been rendered obsolete by synthetic fertilizers.  However, the restored meadows provide a complimentary regulating service by burying approximately 4 g N m-2 yr-1 that might otherwise contribute to eutrophication.  This shift in focus from provisioning to regulating services underscores an ongoing change in the economic importance of coastal systems.