Studying the Ecological Benefits of <i>Spartina</i> Grass Species and Use of a Mathematical Model (Pick’s Theorem) for Historical Documentation and Future Restoration of Hypoxic Marshlands

Abstract

Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best Spartina ( S. ) species to ameliorate the coast. Using graph theory in the Geometer’s Sketch Pad program, progressive land loss from Isles Dernieres was determined from 1853 to 2005. This was accomplished using Pick’s Theorem ( A = I + B /2 - 1), where A = total land area, I = interior intersections, and B = boundary intersections. The analysis indicated that there had been more than ninety percent land loss from 1853 to 2005. Additionally, four plants from each Spartina species ( alterniflora , patens , and spartinae ) were planted and flooded in four containers, respectively, filled with potting soil, and a non-vegetated control was included in this same manner. Dissolved oxygen was measured three times a week under three different temperature regimes, twenty-two, thirty, and ten degrees Celsius, respectively. This resulted in the control group diffusing the most oxygen at twenty-two degrees Celsius, the S. alterniflora diffusing the most oxygen at thirty degrees Celsius, and all the species diffusing statistically similar oxygen levels at ten degrees Celsius. After six months of flooded conditions, penetration and subsidence were measured. The vegetated soils required the greatest penetration forces and subsided the least. Oxygen diffusion is dependent on plant species and temperature. The penetration and subsidence results also support the conclusion that plants can reduce land loss and preserve the coastline.