Hurricane sedimentation in a subtropical salt marsh-mangrove community in the Mississippi River Delta Complex unaffected by vegetation type

Hurricanes periodically deliver sediment to coastal wetlands, such as those in the Mississippi River Delta Complex (MRDC), slowing elevation loss and improving resilience to sea-level rise. However, the amount of hurricane sediment deposited and retained in a wetland may vary depending on the dominant vegetation. In the subtropical climate of the MRDC, the black mangrove (Avicennia germinans (L.) L.) has been expanding and replacing salt marsh (Spartina alterniflora Loisel). Because these vegetation types differ in aboveground structure, their influence on sedimentation may also differ. We conducted a survey for 160 km along the outer coast of Louisiana, USA from Oyster Bayou to the Mississippi River to determine if the spatial deposition pattern in saline wetlands by Hurricanes Gustav and Ike in September 2008 was differentially influenced by vegetation type. Measurements of sediment deposition, land elevation, and vegetative structure were conducted at eighteen sites in the MRDC containing side-by-side stands of A. germinans and S. alterniflora along the shoreline, with S. alterniflora marsh in the interior.