5th UF Water Institute Symposium Abstract

Submitter's Name Katie Glodzik
Session Name Poster Session - Coastal Waters
Poster Number 10
Author(s) Katie Glodzik,  University of Florida (Presenting Author)
  Bill Pine,  University of Florida
  Carrie Reinhardt Adams, University of Florida
  Road impacts to salt marsh salinity and vegetation via interrupted surface flow: observations from four Big Bend sites
  Saltwater intrusion caused by sea level rise and decreased freshwater influence is leading to widespread coastal wetland change along Florida’s Big Bend. Additionally, many coastal wetlands in the Big Bend are bisected by roads that potentially alter local salinity patterns by diverting freshwater and tidal flow. These road networks include “relic” unmaintained roads within protected lands, as well as frequent-traffic county roads. Studies have demonstrated that canals and drainage ditches can convey saltwater inland, but the role of roads in saltwater intrusion has not been examined. We selected four salt marsh study sites (>13 km apart) in the Big Bend Water Management Area and Lower Suwannee National Wildlife Refuge to compare vegetation and porewater salinity between two sides of a road. We hypothesized that (1) roads parallel to the coast reduce tidal flow to inland areas leading to drier conditions, increased evaporation, and higher salinity, and (2) higher inland salinity would cause altered vegetation characteristics, such as salinity stress-induced biomass reductions. At each site, we sampled porewater and surveyed vegetation at 5-9 stations spaced 25 m apart along transects perpendicular to the roads. We also installed shallow groundwater monitoring wells to continuously track salinity. We found differential salinity in sites bisected by roads, although these patterns varied depending on distance from road and site hydrology. Vegetation responses were highly variable. Our results suggest more work is needed to quantify the potential role roadways play in altering coastal areas, including addressing a key uncertainty as to whether roads affect salt marsh vegetation resilience to sea level rise.