PALEOECOLOGY OF NORTHEAST FLORIDA BAY, EVERGLADES NATIONAL PARK, FLORIDA: RECONSTRUCTION OF SALINITY AND HYDROLOGY SINCE 1900

The Everglades of South Florida has a well-documented history of water management over the last century. Prior to 1900, the Everglades region was primarily influenced by seasonal precipitation cycles and topography. During the early 20th century, and again in the 1950s-60s, human development via canals, railroads, and levees greatly altered the freshwater regime of this area. Previous studies have sought a deeper understanding of pre-anthropogenic Everglades water quality in order to create modern targets under the Comprehensive Everglades Restoration Plan (CERP).

The transitional zone of northeastern Florida Bay is slightly more complex than the southern and central portions of the bay. Salinity of the northeastern region is impacted more by freshwater hydrology than by other factors such as tides, wind patterns, local precipitation and evaporation, and storm events. As a result, this area displays water quality changes more directly related to human influence.

To gain further insight into the paleoecological history of the northeastern region of Florida Bay, we used the molluscan record and cumulative weighted percent analysis (CWP) (Wingard & Hudley, 2012) to reconstruct salinity parameters for a piston core collected in February 1995 from Trout Creek, located in the transitional zone (N 25.20910, W 80.53320). From the 74-cm long core, we analyzed 10 evenly spaced 2-cm samples and identified and counted over 25 species of mollusk. Based on the modern molluscan analog salinity dataset and δ¹⁸O isotope data from the bivalve Anomalocardia cuneimeris, freshwater stage and flow were reconstructed for Trout Creek. The resulting data were compared to pre- and post-1900 δ¹⁸O data from Long Sound and molluscan salinity data from nearby Taylor Creek. Wingard et al. (2007) provided the ²¹⁰Pb dating for Trout Creek Core used in this analysis.

Preliminary results suggest that salinity near Trout Creek and northeastern Florida Bay has increased since 1900, most likely a result of the human alteration of freshwater regime. In addition, these data provide more information about salinity changes prior to the 20th century. This study complements the work of many researchers under the CERP and provides new insight into the complicated freshwater system of the northeastern portion of Florida Bay.