THE MORPHOLOGIC AND ANTHROPOGENIC IMPACTS ON SALT MARSH DEVELOPMENT ALONG THE DELAWARE BAY

Holocene salt marshes along the Delaware Bay coast have been developing under the rising sea level for the past 2000 years or so. Humans modified these marshes for almost 400 years by ditching, digging channels and protecting the shoreline from rising sea level and storm impacts. The aerial photo analysis of salt marshes behind the fetch-limited barrier islands near Fortescue, Sea Breeze, New Jersey and Fowler Beach, Delaware revealed both negative and positive feedback mechanism of salt marsh response to natural and anthropogenic factors.

The stratigraphy developed from 35 sediment cores at Fortescue, New Jersey documented that accumulation of salt marsh sediments have been abruptly interrupted by intertidal mud deposition. The changes in sedimentation created sharp contacts between lithologic units suggesting erosion of the salt marsh platform. Three salt-marsh peat and mud sequences identified in Fortescue’s stratigraphy correlate well with regressive sequences documented at Sea Breeze, New Jersey and suggest that depositional changes may be the cause by severe storms (Nikitina, 2014). Erosion under storm surge condition and/or prolong inundation of salt marsh surface kills vegetation and produces accommodation space, which was subsequently filled with intertidal muds, allowing for plants to reestablish salt marsh environments.

Comparison of recent salt marsh responses to impacts of historical storms and human interaction with coastal system with stratigraphic signature of past changes will provide better understanding of salt marsh resilience to environmental factors and past erosion recovery.