Semester of Graduation

Summer 2023

Degree

Master of Oceanography and Coastal Sciences (SOCS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Coastal deltaic wetlands colonize dynamic environments and experience fluctuations of salinity, river connectivity, sediment dredging or deposition, and periods of inundation resulting in unique vegetation and soils. Louisiana’s coastline is experiencing enhanced loss of coastal deltaic wetlands in coastal basins where the Mississippi River no longer is connected to waterways and channels that would normally provide freshwater and sediments representing the abandonment phase of the delta cycle. There is a coastal basin in the central regions of the state, the Atchafalaya Bay, that is still in the active phase of delta cycle resulting in the growth of the Wax Lake, and Atchafalaya Deltas at the mouth of the Atchafalaya River. The Atchafalaya River receive 30% of the combined flows of the Mississippi and Red Rivers that supply freshwater, nutrients, and sediments that enable land building. Observations of silicate concentrations in river water ~60-200 μM in lower Mississippi River stations in St. Francisville and New Orleans are found to be usually stable with occasional variation. We can use the finding of relatively constant silicate concentration to assume that the Mississippi River is a sable stock of silica to Wax Lake Delta (WLD). a major component of sediment and an important micronutrient for vegetation. Vegetation will take up bioavailable silica for protection and growth. Silica is beneficial for plants’ resiliency against toxins, molds, heavy metals etc. Flowers and other structures such as leaves, need silica to have optimal shape and support for growth and photosynthesis. There is minimal existing research on the silica concentrations of the vegetation of WLD. We are interested to see where in the plant most silica is stored and which species out of those in this study contain the most silica on average. The results of this study will begin to fill in the lack of data on the Si concentrations of plants and potentially highlight possible locations of silica fluctuations in deltaic environments. Observations of what plant or plants take up most silica may imply a sink of silica such that it will not reach the water column around it and potentially improving water quality. We found that species in the higher and intermediate zones take up more silica than those in the channel.

Date

5-26-2023

Committee Chair

Twilley, Robert R.

DOI

10.31390/gradschool_theses.5799

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