Paleo-Biological Approaches to Present Day Wetland Ecosystem Restoration Problems

Establishing historic conditions of a site is frequently the first step in ecosystem restoration. Whether restoration to historic conditions is possible or not, recognition of change and the cause of change is critical information. Three different wetland restoration problems are addressed by paleo-biological methods. Chrono-stratigraphy was instrumental in all three cases, 210Pb at the decadal and radiocarbon for the century to millennial scale questions. In order to document salinity, change in the Southeast Saline Everglades molluscan assemblages were utilized as a proxy for salinity. Vertical changes in cores established that beginning in ~ 1900 salinity increased with the Anthropocene Marine Transgression. The freshwater-marine contact in all cores was identified and the contacts dated. The differences in time between two adjacent cores and the distance between them was utilized to determine the rate of saltwater encroachment, documenting that not all coastal basins exhibited the same rate and that the rate increased over time in response to the accelerating rate of sea-level rise, increasing from the pre-1960 rate of ~ 20 m yr-1 to > 80 m yr-1 between 1995 and 2017. This shift in regime suggests that present restoration activities are inadequate. Soon after Audubon acquired Corkscrew Swamp to preserve the largest remaining wood stork rookery, the swamp was diked to hold surface water because it was believed that surrounding land development was adversely impacting swamp hydroperiod. However, by 1970 cypress regeneration was severely reduced and hydrology and sediment core studies were initiated in an attempt to understand the driver of the change. Core analysis revealed that hydroperiod increased upwards terminating in patchy open-water peats, based upon pollen analysis, previous peat analysis and tissue recognition. Open-water peats indicate no drawdown, eliminating cypress germination. Cypress regeneration began soon after removal of the dike.