Coastal Wetland Sediment Influx Variability as the result of Marine Storm-Waters and Continental Water Fluctuations, Dorado, Puerto Rico.

Abstract:

Sedimentary records in inland coastal wetlands are often used to obtain insights on tsunamis or storm frequency on the Caribbean Islands. Ojo del Buey mangrove in the northern coast of Puerto Rico provides an excellent natural sediment trap as it has a natural sand barrier formed by the beach towards the ocean, hence isolating the wetland. The coast line distance varies between 40 to about 150 meters into the wetland. This barrier produces enough distance between the beach zone and the wetland outer boundaries isolating the inner sections of the wetland, which require a higher energy regime for the storm sediments to be carried-in and be deposited. Nevertheless, as inland coastal wetlands are commonly affected by the intrusion of ocean waters, its sediments are commonly in contrast with influx of continental waters. This study has the purpose to identify wetland flooding events recorded by marine deposits as the result of overflow produced by storm events, and the flooding of continental waters recorded by fluvial sediments. These results will be compared with the sedimentary record of previous studies done in Laguna Tortuguero and Caño Tiburones wetlands located at the North side of the island. The two meters of sediment core collected are formed by fluctuations between organic material, silt, sand, and grey clay deposits. The variability of the sediment texture and composition suggests several flooding stages and fluctuations on different water flow energy regimes between ocean or continental waters. To disclose the history of the sedimentary deposits, dating analyses of ¹⁴C are in preparation, along with X-Ray Fluorescence, Loss of Ignition, Particle Size Analyses, Magnetic Susceptibility, and Micromorphology of organic material. These results will disclose the impact of storm and floods of coastal ecosystems that are vulnerable to climatic changes.