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Click below to go to the Cruise Logs - (photo credit: Lophelia Coral - Open-File Report 2008-1148 & OCS Study MMS 2008-015)

DISCOVRE 2009



Cruise Log: 9/21/2009    



Exploring the Deep: Geospatial Tools to Discovering Deep-Reef Ecosystems

Mike Rhode and Andrea Quattrini

Andy Sherrell logs the subdive tracking information while Amanda Demopoulos notes the time, depth, and details for each sample collection - click to enlarge
Andy Sherrell logs the subdive tracking information while Amanda Demopoulos notes the time, depth, and details for each sample collection - click to enlarge
Mapping History
Maps are graphical representations of spatial concepts and are important tools that have been used by humans for thousands of years. Some of the earliest evidence of cartography, or the science of map making, was found preserved in Babylonian clay tablets and date back as far as 2300 B.C. With the Greeks came the introduction of the concept of a round world, from ancient China the oldest existent star maps, and Arab geographers produced the first world atlas, which remained the most accurate map of the world for centuries to come. One of the most significant breakthroughs in cartography, however, was with the invention of printing. Up until that point maps were hand drawn and not widely distributed. It was the printing and dispersal of maps that helped to lead us into what was known as the Age of Exploration. During this age cartographers began producing maps based on exploratory observations and new surveying techniques, and with continued technological advances came additional breakthroughs and applications.

Geographical Information Systems
During the 1970-80s a major shift in cartography occurred. It was at this time that the traditional paper maps advanced into a new concept, a geographical information system or GIS. GIS is a type of mapping software that digitally manages and analyzes data linked to location. It combines remote sensing, land surveying, aerial photography, and geography with mathematics. GIS allows the user to create maps and analyze spatial data using a computer; therefore, information can be easily accessed, transferred and transformed. On this cruise, we are combining GIS with two other types of technology, multibeam sonar and navigational dive tracking. These tools allow us to map and plan our dive locations on the seafloor.

Bathymetry of an area at the West Florida Slope created from multibeam data. Dive (JSLII-09-GOM-3723) locations tracked by the surface support ship are denoted by black circles. Note the beginning and end of the dive track. - click to enlarge
Bathymetry of an area at the West Florida Slope created from multibeam data. Dive (JSLII-09-GOM-3723) locations tracked by the surface support ship are denoted by black circles. Note the beginning and end of the dive track. - click to enlarge
Multibeam Mapping
Multibeam data are collected by echo sounders, which are an array of acoustic transducers mounted to the hulls of ships. These echo sounders send out fan-shaped pulses of sound which are then reflected back off the ocean floor. When the acoustic signals return to the ship they are translated, allowing us to accurately map the topography of the seafloor. This technology has applications in both navigation and cutting edge exploratory research, like ours on deep-sea coral communities. After the multibeam digital data are collected and processed they are imported into GIS, and high-quality geospatial images are produced.

Tracking the Johnson Sea-Link
Getting to our study sites is an expensive and difficult task. The maps produced using GIS allow us to determine optimal target locations for each Johnson Sea-Link (JSL) dive. During each dive, the locations of the submersible on the seafloor are tracked from the surface vessel. Both the science and submersible crew can watch the JSL move across the bottom in real-time, knowing the location of it during the entire dive. They can also communicate with the JSL and provide target locations for the JSL to move to during the dive. These data can then be imported into GIS and overlaid onto three dimensional topographical maps (created from multibeam) of our sites immediately after each dive.

By continuously uploading huge amounts of data collected while at sea, efforts can be directed towards productive, target areas. Specifically, overlaying our collection data and video with the multibeam maps enables us to pin point the locations of deep-sea coral habitats. This allows us to better understand the relationships between deep-coral habitats and the communities associated with them in real time. Data can also be animated to create virtual "flyovers" of sites and to show how sites change over time, displaying trends in the quality and productivity of these habitats. It is also important for this information to be accurately shared with other scientists, government agencies and the public. For this reason, GIS plays a very important role not only in our research, but also in our continued "Age of Exploration!"



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