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2001- Effective Writing (Thin Thesis) Award

The mangrove environment of Southern Florida is expansive, dominating the much of the southern coastline, including that of the southwestern Everglades. As such, it is a dynamic environment that is constantly readjusting the balance between marine and freshwaters. One major question is what has happened in the past; it is difficult to reliably distinguish marine and freshwater deposits in the past. Since 1995, the U.S. Geological Survey (USGS) has been engaged in a large-scale project to acquire high-quality, relevant information on the Southern Florida ecosystem as part of the USGS's Placed-Based Studies Program. In conjunction with this project, various cores of unconsolidated sediment were collected, the portion of one, Core 15-5 is examined in this study.

This study was designed to examine whether or not marine and freshwater Rhizpodia can be used as reliable indicators of marine/freshwater transition zones in the mangrove environment of Southern Florida to help reconstruct past freshwater/marine transition zones. A portion of three cores, Core 15-5 from Little Maderia Bay in Everglade National Park, Core L1011/Hwy 1 from south of Florida City, and Barnes Sound Core, were sampled, processed and analyzed under a stereomicroscope for freshwater thecamoebian and marine foraminifera faunal assemblages.

Results demonstrate marked differences between the peat environments of the three cores. Core 15-5 exhibits a transition from older freshwater peat to marine mud. Core L1011 exhibits a transition from older mangrove peat to freshwater mud. The Barnes Sound Core has mangrove peat in the upper section (Section A) that correlates in age with the peat of Core L1011. Section B of the Barnes Sound Core is marine mud.

Southern Florida is an important ecosystem to study as it contains assemblages of calcareous foraminifera with high diversity assemblages of thecamoebians. The fine scale of environmental differences that these organisms detect make them highly useful indicators of marine/freshwater transition zones in southern Florida.

Keywords:
Pages: 72
Supervisor: David Scott

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