Challenges in using siliceous subfossils as a tool for inferring past water level and hydroperiod in Everglades marshes

Successfully rehabilitating drained wetlands through hydrologic restoration is dependent on defining restoration targets, a process that is informed by pre-drainage conditions, as well as understanding linkages between hydrology and ecosystem structure. Paleoecological records can inform restoration goals by revealing long-term patterns of change, but are dependent on preservation of biomarkers that provide meaningful interpretations of environmental change. In the Florida Everglades, paleohydrological hind-casting could improve restoration forecasting, but frequent drying of marsh soils leads to poor preservation of many biomarkers. To determine the effectiveness of employing siliceous subfossils in paleohydrological reconstructions, we examined diatoms, plant and sponge silico-sclerids from three soil cores in the central Everglades marshes. Subfossil quality varied among cores, but the abundance of recognizable specimens was sufficient to infer 1,000–3,000 years of hydrologic change at decadal to centennial resolution. Phytolith morphotypes were linked to key marsh plant species to indirectly measure fluctuations in water depth. A modern dataset was used to derive diatom-based inferences of water depth and hydroperiod (R2 = 0.63, 0.47; RMSE = 14 cm, 120 days, respectively). Changes in subfossil quality and abundances at centennial time-scales were associated with mid-Holocene climate events including the Little Ice Age and Medieval Warm Period, while decadal-scale fluctuations in assemblage structure during the twentieth century suggested co-regulation of hydrology by cyclical climate drivers (particularly the Atlantic Multidecadal Oscillation) and water management changes. The successful reconstructions based on siliceous subfossils shown here at a coarse temporal scale (i.e., decadal to centennial) advocate for their application in more highly resolved (i.e., subdecadal) records, which should improve the ability of water managers to target the quantity and variability of water flows appropriate for hydrologic restoration.

Links across the Gulfstream: The Florida /Bahamas zone, 1780–1900

The links created between Florida and the Bahamas from 1780 to 1900 constituted a major influence in the evolution of a unique society. This dissertation adds to the understanding of this topic by using primary sources and architecture to follow the odyssey of the people who shaped this region. Building on the historiography which examined each area separately, this work focused on the ties forged in the interactions between Florida and the Bahamas. Following the immigrants who shaped Florida and the Bahamas, this work examines cultural holdovers which influenced this region during times of demographic flux. Aesthetic preferences stood out as one way that people maintained connections to their past. The use of architecture as a lens to view this process provides a concrete example of this phenomenon. The societies of Florida and the Bahamas remained intertwined during the late eighteenth and early nineteenth centuries. Forced migrations shaped the trajectory of the evolution of a distinctive culture in these areas bordered by the Gulfstream. This dissertation proves that the links forged between these societies reinforced the patterns which endured throughout the maturation of this area.