Soil Microbial Processes in Restored and Natural Coastal Wetlands: Controls on Carbon Sequestration and Primary Productivity.

Louisiana contains 40% of the lower 48 United States coastal and estuarine wetlands and also has the highest rates of wetland loss, approximately 80% of the Nation’s total.  It is estimated 4877 km² of land has been lost since 1930. Our study location, Barataria Bay, has one of the highest coastal wetland erosion rates in the nation, at ~41 km² y^-1. Dredged sediment from the Mississippi River is being placed at targeted locations along the coastline in an effort to restore coastal Louisiana marshes. This project seeks to understand how comparable these restored wetland sediments are to those of natural wetlands in Barataria Bay. Soils from both reference (natural) and restored sites were analyzed for soil and microbial characteristics. Moisture content, extractable ammonium and extractable nitrate values were significantly lower in the restored sites. Restored sites contained ~6x lower concentrations of extractable ammonium and ~13x lower concentrations of extractable nitrate. Measurements for Betaglucosidase fluorometric enzyme activity will be presented. These soil characteristics are reflective of soil microbial processes within the wetlands. These valuable services include carbon sequestration, producing available nitrogen for primary production, and converting nitrate to gas (N₂) thus improving water quality. These data are valuable in helping predict the trajectory of restored wetland functions.