First LA-COE graduate student defends thesis

Determining the influence of surface water diversions on physical and nutrient characteristics of wetland soils ($83,328)

John White, Ph.D. Professor of Department of Oceanography and Coastal Sciences, Louisiana State University

Alina Spera, M.S., Department of Oceanography and Coastal Sciences, Louisiana State University

In 2007, a series of 139 stations in the Davis Pond Freshwater Diversion outflow area were sampled by Dr. White for plant type and soil properties of bulk density, total carbon, nitrogen and phosphorus, pH, moisture content, and organic matter content. Now more than 11 years later and with years of operation at Davis Pond Freshwater Diversion, his Master of Sciences’ student Alina Spera led the collection of samples in the same areas to help answer the questions on whether the operation of the freshwater diversion has altered soil properties. These properties include bulk density, carbon content, or nutrient content, all of which are important to coastal marsh growth and resilience in Barataria Basin. Spera and White determined that it’s likely this area now stores about 5,000 more metric tons of carbon due to the influence of the freshwater diversion and that the amount of inorganic phosphorus storage in the soils was seven times higher than a decade ago. Wetland vegetation are likely playing a role in using the nutrients (phosphorus) from the diverted water to build plant material (carbon) that eventually gets accumulated in the soils. These results could help inform the state Coastal Protection and Restoration Authority’s discussions around the continued use of freshwater diversions such as Davis Pond and Caernarvon as well as the long-term influences on the wetland habitat in the outfall areas.