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Systematic Mapping of Bedrock and Habitats along the Florida Reef Tract—Central Key Largo to Halfmoon Shoal (Gulf of Mexico)

USGS Professional Paper 1751

by Barbara H. Lidz, Christopher D. Reich, and Eugene A. Shinn

Introduction: Table of Contents Project Overview Project Objective Geologic Setting Primary Datasets Primary Products - Overview Maps & Evolution Overview: Introduction Depth to Pleistocene Bedrock Surface Reef & Sediment Thickness Benthic Ecosystems & Environments Sedimentary Grains in 1989 Summary Illustration Index Map Evolution Overview Tile-by-Tile Analysis Organization of Report Tiles: 1, 2, 3, 4, 5, 6, 7/8, 9/10, 11 Summary Acknowledg- ments References Disclaimer Related Publications

Tile 7/8 Geography Sector-Specific Studies Natural Stressors: Atmospheric, Terrestrial, and Oceanic Sources Introduction Natural Stressors Atmospheric Sources Terrestrial Sources Oceanic Sources Hurricanes, Storm Surge, and Rising Sea Level Geologic Highlights Margin Evolution Flooding the Florida Shelf Addendum Ephemeral Islands and Lighthouses Terrestrial Sources: Terrestrial stressors include mosquito-control aerosols, residential waste water, marina and canal dredging operations, and storm-water runoff that distribute organic debris, animal wastes, silt, oils, metals, fecal coliform bacteria, pharmaceuticals, viruses, pesticides, nutrients, boat paints, and other contaminants to coastal waters (e.g., Shinn et al., 1994, 1997; Cantillo et al., 2000; Jameson et al., 2002; Porter and Porter, 2002). Shoreline landfills leak contaminants to the groundwater system (e.g., Cantillo et al., 2000). In the keys, onshore cesspits, septic tanks, injection wells, and live-aboard vessels at marinas all supply nutrients, engine fuels, and lubricants to the marine system (LaPointe et al., 1990; Multer, 1993; Shinn et al., 1994). Human activities can often have unintended impacts on terrestrial processes. For example, expanding tarmac acreage that accompanies urban development prevents water absorption into the ground, thereby increasing surface runoff that carries tarmac chemicals. Tarmac also raises heat absorption, altering local temperatures that heat runoff waters. Structures such as inland dams and levees and shoreline groins disrupt the natural flow of water, which increases rates of erosion and sediment buildup in areas where these processes may otherwise be slow or may not occur at all (e.g., Douglas, 1947; Porter and Porter, 2002). continue to: Oceanic Sources

Coastal & Marine Geology Program > Center for Coastal & Watershed Studies > Professional Paper 1751