One goal of the FCE LTER is to investigate how long and short-term variation in water flow, quality, timing, and disturbance influence patterns of primary production
along the freshwater to marine hydrologic/salinity gradient. Primary production is measured at all sites using methods and schedules that are pertain to the dominant plant or algal group present at each site. In the freshwater marsh, we measure primary productivity of sawgrass and periphyton, in the ecotone, we measure productivity by the different species of mangroves and in the marine sites, we measure phytoplankton, seagrass, macroalgae and periphyton.
Research to date has shown that annual net primary productivity (ANPP) of many ecosystem components is enhanced in the ecotone sites of the TS/Ph transect, while ANPP by the dominant macrophytes showed a "wedge" of increasing productivity towards the marine endmember of the SRS transect. Researchers attribute these striking differences in patterns of NPP not only to the stress of P-limitation, but also to variation in inundation times and salinity across FCE freshwater marsh and mangrove communities. In the lower freshwater ecotone, long-term data suggest an increasing effect of salinity as a primary driver of productivity and a strong correlation between the variability in freshwater discharge and lower ecotone salinity, illustrating how upstream water diversion can amplify the effect of SLR. Phase III research establishes a new integrated field and experimental approach to investigate how changes in environmental drivers that determine these gradients shape patterns of production, composition and biomass allocation.
Sawgrass in the freshwater marsh of Taylor Slough
Photo by Mike Rugge
Mangroves at site SRS-6 in Shark River Slough
Photo by Sylvia Lee
Seagrass at site Ts/Ph-10 in Florida Bay
Photo by Jim Fourqurean