Multibeam data were collected aboard the R/V AHI (Acoustic Habitat Investigator), a 25' survey launch owned and operated by the NOAA Pacific Islands Fisheries Science Center in Honolulu, HI, and aboard the NOAA Ship Hi'ialakai, a 218' United States National Oceanographic and Atmospheric Administration research ship. The R/V AHI's survey sensors include a 240 kHz Reson 8101-ER, the sonar providing multibeam bathymetry and backscatter data, and a Seabird SBE 19 CTD used to measure sound velocity profiles, whereas the NOAA Ship Hi'ialakai's survey sensors include a 30 kHz Simrad EM300 sonar and a 300 kHz Simrad EM3002d sonar, which provide bathymetry and imagery data, and a Seabird SBE 9/11 plus CTD used to measure sound velocity profiles. Both systems include a TSS/Applanix POS/MV Model 320 which measures position, velocity, attitude and heading. Specific equipment configurations are documented in metadata from cruises: AHI0402, AHI0602, TC0201 and OES0402. These metadata can be accessed at: <http://www.soest.hawaii.edu/pibhmc/pibhmc_cruise>- catalog.htm
Optical imagery of the seafloor is collected primarily to validate the interpretation of benthic habitat characteristics from multibeam echosounder surveys. Optical data were collected using two different methods. In shallow waters of depths between a few meters and 20-30 m, towboard divers with the Coral Reef Ecosystem Division (CRED) collect video or still imagery while being towed behind a small boat over track lines pre-programmed into a handheld GPS unit. The majority of seafloor in the area is deeper than the approximately 30 m maximum depth attainable by towboard divers. The habitat in these deeper areas is assessed by Towed Optical Assessment Device (TOAD), a sled equipped with underwater video camera, still camera, and lights. Camera sled deployments were conducted at night, usually between 1800 and midnight, to avoid interfering with daytime small boat and diver operations. The TOAD was originally deployed from a pot hauler mounted on the starboard side of the fantail on NOAA Ship Townsend Cromwell. On the NOAA Ships O.E. Sette and Hi'ialakai various iterations of TOADs were deployed off the portside J-frame amidships or the starboard side J-frame respectively. In all cases the sleds were lowered slowly to the bottom by the deck crew with the use of a capstan. The TOAD operator monitored a live video feed from the camera and began recording data on two video tape recorders. When the camera reached bottom the deck crew was notified by radio to stop lowering, and the ship moved off along a predetermined course, towing the TOAD astern for the first TOAD, or by drifting with subsequent camera sleds. The operator continued to monitor the vehicle and provided commands to raise or lower it to keep the camera just above the bottom. Specific equipment configurations are documented in metadata records: cred_toad_tutuila_2002 cred_toad_tutuila_2004 These metadata can be accessed at (Located under Optical Validation): <http://www.soest.hawaii.edu/pibhmc/pibhmc_amsamoa_tutuila_optical.htm>
All collected video is classified for substrate and living cover according to the key, which can be downloaded from: <ftp://ftp.soest.hawaii.edu/pibhmc/website/webdocs/webtext&figures/bh_class_codes.htm>
Geomorphology layers (slope, rugosity, Bathymetric Position Index Strcutures and Zones) are derivates of multibeam bathymetry. These layers may be used for benthic and essential fish habitat characterization, and for the study of geologic features. By combining the dataset with bathymetry, backscatter, other derivatives, and in situ data, they collectively compose benthic habitat maps which are designed to be used to understand and predict moderate depth (~20m - 150m) benthic habitats for different organisms that inhabit coral reef ecosystems.
Benthic habitat layer names, with start and end dates:
Bathymetry, 5 meter grid: 20040130-20060313 Backscatter Imagery, Reson 8101 16 meter grid: 20040217-20060308 Backscatter Imagery, Reson 8101 1 meter grid: 20040217-20060308 Backscatter Imagery, Simrad em3002d 16 meter grid: 20060217-20060224 Backscatter Imagery, Simrad em3002d 1 meter grid: 20060217-20060224 Optical Validation via TOAD video: 20020210-20040226 Optical Validation via Towboard (towed-diver observations): 20020209-20060309 Geomorphology Layers, Slope: 20060430-20070115 Geomorphology Layers, Rugosity: 20060430-20070115 Geomorphology Layers, Bathymetric Position Index Structures: 20040130-20070112 Geomorphology Layers, Bathymetric Position Index Zones: 20040130-20070112 Nautical charts (NOAA Chart # 83484) available for download: <http://chartmaker.ncd.noaa.gov/mcd/Raster/download.htm>
All related information is available in the original form at: <http://www.soest.hawaii.edu/pibhmc/pibhmc_amsamoa_tutuila.htm>
Resource Description: Map layers of bathymetry and other biologically important characteristics of the coral reef ecosystem around Tutuila, American Samoa, incorporated into independent ArcGIS and ArcReader projects.