Open-File Report 97-0534

Progress Report on Sediment Analyses at Selected Faunal Monitoring Sites in North-central and Northeastern Florida Bay

By Thomas M. Scott, Guy H. Means and G. Lynn Brewster-Wingard

This is a cover page. To go to the actual document, click on the title above.
The document is in PDF format (3,190 K). You will need Acrobat Reader to view and print. If you do not have Acrobat Reader, you will need to download the program.
Click here to download Adobe Acrobat 3.0, and follow the download and installation instructions provided. After downloading Acrobat, configure your browser to use Acrobat as a helper application.


Florida Bay is a shallow, subtropical lagoon at the southern tip of the Florida peninsula. The 2200 square kilometer, triangular-shaped area is the site of modern carbonate sediment formation and deposition. The intricate ecosystem of the bay has undergone significant changes as the result of natural influences and human intervention. The purpose of this study is to investigate carbonate sediment characteristics and distribution in conjunction with faunal and floral to determine the substrate preferences of associated fauna and flora. The modern data provide the proxy data for down-core analyses of sediments, fauna and flora in order to document ecosystem changes in the bay.

Selected sediment samples collected during 1996 from 18 sites in the northeastern and central bay were analyzed for insoluble residues, organic content, total carbonate, and percent of silt and clay sized particles. Insoluble residues range from 0.8% of the sediment in a shell lag to 11.5% with an average of 5.1%. Organic content ranged from a minimum of 1.43% of the sediment to 18.05% with an average of 7.6%. The total carbonate content ranged from 72.56% to 97.81%, averaging 87.98%. The percent silt and clay sized particles ranged from 13.75% to 63.62% for the samples analyzed. The insoluble residue content shows a general trend of decreasing insoluble residues from the northeastern bay toward the southwest. Organic content is variable throughout the bay and does not show a regional trend. Several sites show a trend of higher organic content in the samples collected in February as compared to those collected in July.

Lithologic examination indicated that, in addition to the carbonate mud (less than 63mm), sample components included whole and fragmented mollusks, foraminifers, bryozoans, ostracods, and organic matter. The insoluble residues consisted of quartz sand and silt, clays and siliceous fossils. A component of the insoluble residues may be dust derived from Africa and transported to southern Florida by the prevailing winds.

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Information for ordering U.S. Geological Survey maps and reports
is available by calling 1-888-ASK-USGS. Information for ordering
USGS products also is available from the USGS home page on the
World Wide Web at URL

You can write to

USGS Information Services
Open-File Reports
Box 25286
Denver, CO 80225

Fax: 303-202-4695

Return to Geologic Mapping and Regional Geologic Studies in the Eastern United States
Return to Open-File Reports
Return to Geologic Information

Maintained by John Watson
Last Updated 05.17.99