Benthic Habitat Mapping - Dry Tortugas RoxAnn Acoustic Sensor Data Points

During April 2001 RoxAnn single-beam acoustic surveys were conducted at the North Unit of the Tortugas Ecological Reserve, Florida. Thirteen transects associated with fixed bottom sampling stations were surveyed to characterize the ecotone around the stations. In addition survey tracks were run along the outer edge of the Tortugas platform reef complex and into the interior of the platform. A towed video sled (minibat) was deployed simultaneously with the RoxAnn survey which provided a live video ground truth to the acoustic signals. Using this ground truth several bottom classes were identified including coral, seagrass, algae, unconsolidated sediments, and hardbottoms. The original RoxAnn categories are preserved in the Class field and benthic habitat codes from the Florida System for Classifying Estuarine and Marine Environments (SCHEME) system are preserved in the SCHEME field. The depth value is in meters below transducer surface.

Original contact information:

Contact Org: NOAA Office for Coastal Management

Phone: 843-740-1202

Email: coastal.info@noaa.gov

The single-beam surveys were part of a larger biogeographic characterization effort intended to characterize benthic habitats, ocean circulation patterns, in the newly established Tortugas Ecological Reserve. The goal of the project was to establish a baseline of environmental conditions and processes that could be compared to future surveys. This would support evaluations of various reserve management strategies.

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Single-beam acoustic data points collected in the Dry Tortugas area of Florida. While every effort has been made to ensure that these data are accurate and reliable within limits of the state of the art, NOAA will not assume any liability for damages caused by any inaccuracies in these data, or failure in their use.

None

Bathymetric data have not been corrected for tide and wind variables. Not for use in navigation.

ArcView version 3.2 shapefile format

This data is accurate to field conditions in April 2001. The depth readings have not been corrected for tide stage or wind variables. A towed video system (mini-bat) was deployed behind the vessel where the acoustic transducer was deployed. This provided real-time ground-truth to the acoustic signals. As habitat boundaries were crossed, the RoxAnn acoustic signature box was updated and checked. In addition dive observations were made along the transects to verify the habitat classes.

The horizontal positional accuracy is based on the accuracy of the GPS used to generate the coordinate pair for each acoustic record. The GPS unit was a military grade receiver enabled to receive encrypted Y-code from the GPS satellites. his typically produces a spatial accuracy of 10 meters or less.

Depth value is in meters below transducer. No correction has been applied for wind or tide effects. No validation was performed on this data and no accuracy is implied.

The data is complete.

These data are believed to be logically consistent, though no tests have been performed. Point geometry is topologically clean.