Salinity Intrusion Impacts from Hurricane Sandy in Tidal Freshwater Swamps, Delmarva Peninsula, Mid-Atlantic Coast, USA

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When it comes to hurricanes, wind and storm surge effect vegetation differently. USGS anlyzes these differences following Hurricane Sandy to help inform management on storm mitigation and long-term planning. 

Evelyn Anemaet using an RTK to determine elevation of tidal swamp near the mouth of the Pocomoke River, MD
WARC scientist uses an RTK to determine elevation of tidal swamp near the mouth of the Pocomoke River, MD

Science Issue and Relevance: Hurricane wind and surge have different effects on vegetation. While wind damage from Hurricane Sandy was most severe at the point of landfall (New Jersey), inundation occurred along the entire eastern seaboard from Georgia to Maine, exposing freshwater wetlands to saltwater intrusion. In this study, a comparison of wind vs. salinity damage was recorded in swamps of the Delmarva Peninsula along the Pocomoke (MD) and Nanticoke (DE) Rivers, south of the most intense wind damage. This study will provide information on post-storm environments (wind vs. salt damage) to help inform management on mitigation and long-term planning.

Methods for Addressing the Issue: We are examining the long-term revegetation of baldcypress forests after Hurricane Sandy. Rates of tree production, growth, and regeneration are being monitored in study swamps along the Pocomoke and James Branch Rivers, Maryland and Delaware, respectively. The tidal swamp closest to the Chesapeake River (e.g., Hickory Point State Forest) experienced saltwater intrusion during Hurricane Sandy, and subsequently, some standing freshwater forest species died. In the created tree gaps, forest regeneration took a number a number of years, and emergent species with more salinity tolerance (e.g., cattail) established and spread. Researchers are looking at the vegetation shifts following Hurricane Sandy to determine if they are due to an inability for freshwater tree species to establish in higher levels of salinity (>4.0 ppt).

Future Steps: The project establishes a baseline for long−term studies of biodiversity shifts following saltwater intrusion by tracking vegetation production, growth, and regeneration.

Related projects: Modeling the connections between surface and groundwater hydrology, water quality, and ecosystem health across the Gulf Coast of the US.