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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

Project Objective The objective of systematically mapping seabed features along the Florida reef tract is to maximize the value of geologic/biologic research conducted in that part of the Florida Keys National Marine Sanctuary for which the contiguous datasets are available. By providing easy-to-use descriptive and interpretive digitized map products and shelf-edge evolutionary models as multiple baseline datasets, this report contributes to a long-term regional and ecosystem-based research program to improve our understanding of processes that govern the structure, function, and health of coral reef ecosystems. The goal is to provide managers with tools (Table 1) to: help delineate natural change from that induced by human activities; integrate scientific knowledge of ecologic relations with informed stewardship practices for the purpose of implementing sustainable ecologic, cultural, and socioeconomic systems; predict variability and evaluate influence of coastal processes and ecosystem response to natural (rise/fall of sea level) and anthropogenic effects (contaminants) through increased understanding of the close linkage between, and variety in, physical environments and biological communities; implement protective measures; increase scientific understanding of the critical equilibrium (between physical processes and geologic framework) required to maintain the fragile environments; weigh the delicate balance between permitting salvage of unique 16th-, 17th-, and 18th-century archeological finds (shipwrecks) or establishing aquatic archeological preserves to minimize ecosystem impact; inform and educate the visiting public with current scientific understanding of how and why the reef-tract resources exist, how and why each component is an integral part of the ecosystem, and how and why these resources can be damaged or destroyed. Project products provide high-quality detailed information on bedrock topography and depth below sea level, thickness of the sediment cover, areal extent and types of fragile habitats and seemingly barren sites, and coral health as derived from the coral-grain percentages within the sand. This information is used to evaluate proposed placements of mechanical installations such as lighthouses, marker light buoys, and mooring buoys, and to site locales most suitable for coral and seagrass restoration after damage by storms and ship groundings. An essential outcome of the geologic interpretation of the maps and shelf-edge models is a clear understanding of why and when coral reefs developed where they did. continue to: Regional Geologic Setting

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