U.S. Department of the Interior
U.S. Geological Survey
OFR 2007-1203

ABSTRACT

²¹⁰Pb, ¹⁴C, and pollen biostratigraphic data have been compiled and synthesized to develop age models for cores collected from Florida Bay and Biscayne Bay. These cores are being used to interpret the ecosystem history of south Florida's estuaries by examining the physical, chemical, and biological record preserved within the cores. The beginning of the 20^th century, which marks an important turning point for the natural vs. anthropogenically influenced ecosystem, has been identified based on at least two data points in ten cores. ²¹⁰Pb data alone are presented for an additional 38 cores. Age models for older sediments have been developed for seven cores. Comparison of pre-1900 and post-1900 records allows researchers to compare natural ecosystem changes to anthropogenic change.

General patterns of sedimentation rates in Florida Bay and Biscayne Bay emerge from the data. Mid-bay mudbanks in both bays show more rapid rates of sedimentation, fewer signs of sediment disruption, and more internal consistency of sediments than cores located closer to shore. Nearshore cores indicate slower average rates of sedimentation, more disruption in the sedimentary sequences, and more indications of “old” carbon effects. Cores in close proximity to each other generally show very similar patterns of deposition, which indicates support for the age models.