Foundation Species Shift Alters the Energetic Landscape of Marsh Nekton

Climate change driven sea level rise and mangrove expansion are rapidly altering coastal systems in the northern Gulf of Mexico. Such substantial and wide-spread change will likely have substantial effects on the flow of energy through the food webs in these systems. Using stable isotopes and habitat cover maps, we built energetic landscapes ( E- scapes) for three nekton species to determine how the landscape’s ability to produce energy changes with changing habitat cover over a 5-year period. Between 2015 and 2020, 25% (367.26 ha) of marsh habitat converted into mangrove habitat and 10% (144.93 ha) of marsh habitat transitioned into water. We observed an overall decrease in the energetic benefit to all consumers with increasing mangrove cover, due to the fact mangrove detritus is not used as a food source by consumers in our system. Edge habitat had a positive relationship with overall energetic production, likely due to the increase in available area for benthic algal production. The relationship between edge habitat and water habitat suggests that while these areas may initially increase in their ability to support consumer species, continued sea level rise will lead to reductions in the landscape’s ability to produce energy for consumers as land is converted to water. As these coastal areas experience rapid habitat cover changes, the reduction in energetic quality of habitats could lead to a reduction in the ability of these systems to support existing consumer species.