Spatial and temporal patterns in short-term surface sediment deposition and accretion at the Guana Tolomato Matanzas National Estuarine Research Reserve: Implications for resilience of coastal wetlands to sea-level rise

Abstract

Coastal wetlands are at risk of drowning due to the increasing threat of rising sea levels. Wetlands will have to build in elevation vertically or migrate horizontally to survive. Previous research has demonstrated that some wetlands have the potential to naturally build in elevation over time if deposition and accretion rates from allochthonous sediment delivery are substantial, but work in this area has been limited, and many coastal wetlands remain understudied. Portions of Northeast Florida are especially lacking in short-term surface deposition and accretion data. Without surface rates it is difficult to determine the vulnerability of different wetlands to rising sea levels. This project aims at measuring short-term surface deposition and accretion rates and identifying factors that drive rates in Northeast Florida. For this study, several short-term surface sediment deposition and accretion methods were tested during a 28-day deployment within the Guana Tolomato Matanzas National Estuarine Research Reserve (GTMNERR) to determine which methods were most effective at measuring rates. Ceramic tiles, borosilicate filters and centrifuge tube traps were deployed in varying wetland communities within the Reserve. Some methods were stapled and nailed to test ways to prevent dislodgment during deployments. The methods that were effective were then used during a yearlong study to measure short-term surface deposition and accretion rates seasonally in different wetland communities at the GTMNERR. It was found that the centrifuge tube trap and stapled ceramic tiles were the most efficient methods to measure short-term surface deposition and accretion rates. The main factors driving rates were platform edge distance, elevation, site and season. The results of this project will help to fill the data gap on short-term surface rates in the GTMNERR, Northeast Florida and beyond, which will inform management decisions to improve the resilience of coastal wetlands with rising sea levels