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

Introduction

South Florida is currently undergoing a massive restoration effort guided by the Comprehensive Everglades Restoration Plan (CERP). A key component of the CERP is “to restore, protect and preserve the water resources of central and southern Florida” (CERP, 1999). In order to restore the natural freshwater flow through the ecosystem, it is imperative to understand the environment of south Florida prior to significant human alteration. To this end, the USGS has conducted research on patterns of physical, chemical and biological processes in the south Florida ecosystem on time scales ranging from decades to millennia. These studies use proxy evidence from sediment cores collected throughout the Everglades wetland, Florida Bay, and Biscayne Bay to reconstruct historic and longer-term patterns of water quality and chemistry, wetland water depth, and hydroperiod. A goal of the research is to separate out the natural changes that have occurred in the system from the anthropogenically induced changes. In south Florida, the beginning of the 20^th century is commonly considered the period in which human influence on the environment became extensive (Lodge, 2005; Light and Dineen, 1994; McIvor and others, 1994; McPherson and Halley, 1996).

Accurate age models are essential to attribute biotic change observed in sediment cores to specific environmental or climatic causes and to evaluate the influences of natural vs. anthropogenic factors on critical ecosystems. Core collection in Florida and Biscayne Bays began in 1994, and several laboratories and methods were used to construct age models for the individual cores. The goals of this report are 1) to compile, standardize, and augment the age information we currently have for cores collected in Biscayne Bay and Florida Bay; 2) to provide estimates of the errors associated with those ages; and 3) to determine what additional work can be done to improve the reliability of age models in recent sediments in south Florida. The information presented in this report revises some previously published age models for the ecosystem history cores (Brewster-Wingard and others, 1997, 2001; Brewster-Wingard and Ishman, 1998; 1999; Cronin and others, 2001; Dwyer and Cronin, 2001; Ishman and others, 1996 (data revised); 1998; Stone and others, 2000; Trappe and Brewster-Wingard, 2001; Wingard and others, 1995 (data revised); 2003; 2004).

Acknowledgements

We would like to thank our reviewers Thomas Cronin (USGS, Reston, VA) and Robert Halley (USGS, St. Petersburg, FL) for their helpful comments and suggestions. A number of people have assisted in the collection and processing of the cores discussed in this report, including Robert Halley, Eugene Shinn, Scott Ishman, Don Hickey, Chris Reich, James Murray, Rob Stamm, Carlos Budet, Ruth Ortiz, Katie Waylen, Jill D'Ambrosio, Nancy Carlin, Steve Wandrei, Lauren Hewitt, Jeffery Stone, Carleigh Trappe, and Sara Schwede. Assistance with pollen preparation and quantification was provided by Lisa Weimer, Bryan Landacre, and Tom Sheehan. Christopher Bernhardt and Carlos Budet assisted in the preparation of the location maps for this report. Radiocarbon analyses were done by Beta Analytical (Miami, FL) and the USGS Radiocarbon Lab, run by Jack McGeehin (Reston, VA). Ruth Ortiz and Carlos Budet assisted in the final preparation of this report.

We would like to thank Everglades National Park and Biscayne National Park for their assistance in providing access to field sites and use of park facilities. South Florida Water Management District provided funding for the collection of the 2002 and 2003 Biscayne Bay cores. This work has been funded by the South Florida Study Unit of the USGS Priority Ecosystems Program and this report is part of the Synthesis of South Florida Ecosystem History Research Project.