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Along-Track Reef-Imaging System (ATRIS) Used to Survey the Sea Floor in Dry Tortugas National Park, Florida
The Dry Tortugas, a cluster of islands approximately 65 mi due west of Key West, FL, encompass the coastal and marine environments where pioneering researchers conducted baseline studies of south Florida coral-reef organisms at the remote Carnegie Tortugas Marine Laboratory, located on Loggerhead Key, until its closure in 1939. U.S. Geological Survey (USGS) employee Thomas Wayland Vaughan spent summers from 1908 to 1915 and 1922 to 1923 conducting coral-reef research at the laboratory. The history and visual aesthetics of the low-lying carbonate keys bring hundreds of visitors every day to tour the Civil War-era Fort Jefferson on Garden Key and to snorkel in the clear tropical waters.
To build on previous research efforts, a team from the USGS St. Petersburg Science Center in St. Petersburg, FL, led by John Brock participated in the first comprehensive surveys in the Dry Tortugas using the Along-Track Reef-Imaging System (ATRIS) from June 13 to 26. ATRIS combines high-resolution bathymetry, underwater digital photography, underwater video, vessel-heave compensation, and differential Global Positioning System (GPS) data to provide photographic and video transects of the sea floor keyed to precise geographic locations and water depths.
The field team, composed of John Brock, Phil Thompson, Russ Peterson, Jerry Butcher, and Don Hickey (all from the St. Petersburg office) and Ramon Lopez (Ph.D. candidate from the University of Puerto Rico, Mayagüez), monitored real-time collection of imagery (digital photography and analog video) and bathymetric, GPS, and heave data. They also conducted quality-assurance procedures in the evening to ensure successful data acquisition and backup for the day's efforts. They processed thousands of images in the field each day, using the ATRIS Data Analysis and Processing Tool (ADAPT) software developed by David Nagle (St. Petersburg).
The USGS has engineered the ATRIS to acquire continuous digital still images of the sea floor during transects across shallow-water reefs for use in the creation of benthic-habitat maps. This tool gives scientists the ability to combine field observations from the along-track vessel-mounted sensor package with IKONOS and QuickBird commercial satellite imagery to monitor and map in detail an area's bathymetry and benthic-habitat composition. Ramon has already completed his preliminary Dry Tortugas benthic-habitat-characterization analyses by resolving available IKONOS and QuickBird imagery with the newly acquired ATRIS data set.
William Longley and Charles Martin at the Carnegie Tortugas Marine Laboratory obtained the world's first recorded underwater color photographs in the 1920s. Since then, the significance of underwater imagery for research and management has continued to grow. Clearly, underwater photography has advanced considerably over the past century, and this progress was emphasized daily throughout this field exercise. The ATRIS components effectively functioned concurrently, compiling approximately 50,000 underwater digital images and 50 hours of underwater video footage of the various marine benthic habitats within the boundaries of Dry Tortugas National Park.
The successful data acquisition will provide a complementary data set to a National Aeronautics and Space Administration (NASA) Experimental Advanced Airborne Research lidar (EAARL) survey of Dry Tortugas National Park completed by NASA and USGS researchers in August 2004, before Hurricane Charley. The high-resolution lidar (LIght Detection And Ranging) data set includes marine-topography and subaerial-elevation information, providing researchers and managers with centimeter-scale bathymetric and geographic information to assist in current and future studies, as well as management planning. Though not a primary objective of this ATRIS survey, comparison of the two data sets (lidar and ATRIS) may be possible in order to identify modification of coastal and marine environments by several strong storms that passed through the region during the data-acquisition period (August 2004-June 2005).
Many logistical difficulties with work in this remote location were alleviated by the support offered by Dry Tortugas National Park employees Ranger Willie Lopez (Site Supervisor), Brion Shaner, Niki Ryan, and Captain Linda Vanaman. We also appreciate the efforts of the other Dry Tortugas National Park employees and volunteers. We were fortunate to participate in a lantern tour of Fort Jefferson during the first week of our field trip. Park Volunteer Mike Ryan, dressed in a Civil War-era Union soldier's uniform, led a captivated audience through the fort while relating 150 years of historical highlights.
We conducted our fieldwork approximately 100 years after the first investigators arrived at the newly established Carnegie Tortugas Marine Laboratory. A century of Dry Tortugas coral-reef research is a milestone worthy of recognition, and so a Centennial Celebration of the Carnegie Tortugas Marine Laboratory is scheduled for October 13-15, 2005. Gene Shinn (St. Petersburg) is a member of the Centennial Organizing Committee and has been instrumental in the inception and development of the event. The Centennial Celebration includes a field excursion and symposium on the past, present, and future of research in the Dry Tortugas. Visit URL http://www.rsmas.miami.edu/conference/tortugas/ for more information.
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ATRIS Used to Survey Sea Floor in Dry Tortugas National Park
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