Varying Inundation Regimes Differentially Affect Natural and Sand-Amended Marsh Sediments.

Area of Science:

• Coastal Ecology
• Environmental Science
• Geomorphology

Background:

• Climate change impacts sea level rise and precipitation, threatening coastal wetlands.
• Coastal wetland management requires understanding system responses to stressors.
• Thin layer sediment application is a strategy to enhance marsh elevation and resilience.

Purpose of the Study:

• To evaluate the effects of thin layer sand application on marsh sediment characteristics and plant productivity.
• To assess the viability of sand application as a climate adaptation strategy for coastal wetlands.

Main Methods:

• Field experiment at Plum Island Sound Estuary, MA, with natural and sand-amended marsh sediments.
• Varied inundation regimes from mean sea level to mean high water.
• Measured above- and below-ground structure, CO2 emissions, pore water constituents, and belowground biomass using CT imaging.

Main Results:

• Sand-amended sediments showed lower salinity, pH, sulfides, phosphates, and ammonium compared to natural sediments.
• Salinity patterns reversed in sand-amended sediments with elevation.
• Despite initial differences, both treatments exhibited similar belowground biomass and productivity by the end of the growing season.

Conclusions:

• Thin layer sand application is a viable climate adaptation strategy for building coastal wetland elevation and resilience.
• This method is particularly effective in areas with low natural sediment availability.
• The approach supports organic matter accumulation and peat buildup, crucial for marsh health.