By: Jacob Berna

Hello NERRds, my name is Jacob Berna, and I am a biologist at the GTMNERR and a graduate fellow at the University of North Florida. For my masters project I am studying short-term sediment accretion and deposition rates in mangrove and smooth cordgrass marsh communities within the GTMNERR. The goal of the project is to determine how sediment rates may be influenced by different vegetation communities, marsh elevations, sediment compositions, and seasons.

To measure sediment accretion and deposition, I deploy accretion tiles and deposition traps quarterly for a month (~28 days) at a mangrove site in East Creek and a smooth cordgrass site in Deep Creek. The deposition traps collect “gross” sedimentation (deposition without erosion), while the accretion tiles collect “net” sedimentation (deposition with erosion). Comparing the deposition and accretion rates can show the short-term erosion rates of sediment that is deposited.

At the two sites where the tiles and traps are deployed, I will also be measuring surface elevation and vegetation composition (cover, canopy, and stem densities). In addition, portions of the accreted and deposited sediment will be sent off for lab testing for particle size analysis and stable isotopes. This covariate data will be compared to sedimentation rates to identify how certain factors such as stem density or particle size may influence rates. 

The results from this study will demonstrate the effectiveness of using deposition traps and accretion tiles to measure rates in southeastern coastal marshes. The study will also help to fill the knowledge gap on sedimentation rates in our area. Understanding rates is essential for coastal resilience to identify marsh vulnerability to future storms and sea level rise.