Abstract >Introduction - Setting Acknowledgements Material and Methods Results Discussion Significant Findings, Implications And Future Work References Appendices PDF version

During the last century, Biscayne Bay has been greatly affected by anthropogenic alteration of the environment through urbanization of the Miami/Dade County area and alteration of natural freshwater flow patterns. The sources, timing, delivery, and quality of freshwater flow into the Bay have been changed by construction of a complex canal system that controls movement of water throughout south Florida (SWIM, 1995). Changes in shoreline and sub-aquatic vegetation and marine organisms observed during the last century have been attributed to changes in water delivery.

Current restoration goals include restoration of the natural flow of fresh water into Biscayne and Florida Bays and of the natural fauna and flora, but first we need to determine pre-alteration baseline conditions in order to establish targets and performance measures for restoration. This research is part of an ongoing study designed to address the needs of the Biscayne Bay Coastal Wetlands Project (BBCW) of the Comprehensive Everglades Restoration Plan (CERP). The purpose of the BBCW Project is "to rehydrate wetlands and reduce point source discharge to Biscayne Bay" (http://www.evergladesplan.org/pm/projects/proj_28.cfm) and the project identifies the need to "define target freshwater flows for Biscayne Bay and the wetlands."

Examination of natural patterns of temporal change in salinity, water quality, vegetation, and benthic fauna in Biscayne Bay and the nearby wetlands during the last 100-500 years provides data necessary to set realistic targets to achieve the BBCW Project goals. Long term data covering decadal to centennial scale change is necessary in order to understand components of change due to natural cycles and to set targets that encompass the natural range of variation present within the ecosystem.

Cores collected in sediment deposits retain information about the history of an ecosystem in the sediments themselves and in the fauna and flora preserved in the sediments. A multiproxy approach utilizes several major groups of animals (forams, ostracodes, and mollusks - over 150 faunal groups in all), pollen, and geochemical data to determine past sequences of change to the environment and derive information on the physical, chemical and biological components of the environment. The interpretations of the faunal and floral assemblages in the cores are based on observations and analyses of modern organisms (Brewster-Wingard and others, 2001; Cronin and others, 2001; Ishman, 2001). By using multiple proxies, we are able to derive more detailed information, examine the covariance of environmental indicators, and increase confidence in the results. This approach, utilized in this study, has been successfully applied to research in Florida Bay and in a previous project in Biscayne Bay (Brewster-Wingard and others, 1998; Brewster-Wingard and Ishman, 1999; Ishman and others, 1998; Nelsen and others, 2002; Wardlaw, 2001).