The Chandeleur Islands, a barrier-island chain off the coast of southeastern Louisiana, have undergone extensive erosion and land loss driven by insufficient sand supply, sea-level rise, and tropical cyclones. The shallow back-barrier area of the Islands supports seagrass meadows, which have also declined over time. The central hypothesis for this study is that seagrass decline is primarily driven by loss of island protection, which alters local hydrodynamic conditions and sediment transport patterns, creating a more energetic back-barrier environment that is less conducive to the survival or establishment of seagrass meadows.

To test this hypothesis and better understand the drivers of seagrass decline, an integrated framework was developed that combines field observations, remote sensing, and numerical modeling. Field data provides insight into recent seagrass coverage and hydrodynamic conditions within and outside seagrass beds, while remote sensing offers a long-term record of changes in seagrass extent. Numerical modeling, representing several recent historical island configurations, was used to evaluate how evolving topography, bathymetry and seagrass coverage influence waves, currents, and sediment transport. 

The results provide insight into the loss of seagrass meadows in recent history, and whether this was primarily due to direct hurricane impacts (i.e., uprooting or burial of seagrass) or indirect effects (i.e., increased wave exposure due to loss of island protection). The model experiments improve understanding of the hydrodynamic and sediment transport conditions within the meadows and help identify the conditions associated with seagrass decline, particularly for areas that have become increasingly exposed to wave energy.