Optical validation data were collected using a Tethered Optical Assessment Device (TOAD), an underwater sled equipped with an underwater digital video camera and lights, in the Saipan Anchorage area. Data were collected using TOAD during two and a half weeks of small boat-based TOAD deployments. A report detailing results of the study was generated to assist the Military Sealift Command in their efforts to increase the number of pre-position vessels stationed there.
These data provides optical observations that have been used to provide information on the distribution of coral communities in Garapan anchorage out side of Saipan Harbor, CNMI.
Saipan, the largest of the Northern Mariana Islands, has a land area of 122 km2 and is approximately 20 km long and 9 km wide. The island consists of a volcanic core enveloped by younger coral reef-derived limestone formations. The island has the most diverse types of coral reefs and associated habitats in the Commonwealth. A fringing and barrier reef system protects the majority of the beaches along the western and coastal plains. The western side of the island is the most populated and the coral reefs along these areas are negatively affected by human activity. Continuing sediment and nutrient pollution combined with sporadic stressors such as outbreaks of crown-of-thorns starfish (COTS) (Acanthaster planci) and temperature-induced bleaching affect many of Saipan's western and southeastern reefs. Furthermore, coral habitat on two large offshore banks (18 km x 22 km) in water depths between 30 m and 60 m on the western side of Saipan are negatively affected by the anchorage of commercial and naval vessels. It is these two banks that were the subject of the study reported here. Optical validation data were collected the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video camera and lights. These data are used to provide optical information regarding benthic and fish communities. They have also been used to provide ground-truth validation for benthic habitat maps based on multibeam echosounder surveys, but these are presented in a separate product, available on the PIBHMC website. From December 3-16 2004, CRED personnel and contractors conducted towed video surveys in the Saipan Anchorage, CNMI aboard the 62-ft-long Carolinian, one of the vessels owned and operated by Saipan Crewboats, Inc., and regularly chartered by the U.S. Navy. Operations were conducted during daylight hours, with video data collected using a new underwater camera sled, designed and fabricated by Deep Ocean Engineering, Inc. (DOE). The camera sled was attached via umbilical cable to a control console located on board the Carolinian. The camera sled was deployed from the port or starboard side of the Carolinian depending on the prevailing current and wind conditions. A video display monitor mounted on the control console was used to monitor the position of the sled relative to the seafloor. Instructions to raise/lower the sled were relayed to CRED personnel on deck to maintain close proximity of the sled to the seafloor and to avoid collisions with seafloor highs. Equipment Description: The TOAD sled body is constructed from a shortened Phantom ROV body with a tail piece added for stability. It is equipped with a Deep Sea Power & Light Multi SeaCam 2060 color video camera, two 500 W DeepSea Power & Light Multi-SeaLite model 1050 underwater lights, a sonar altimeter to detect the height of the camera above the seafloor, a pair of parallel lasers to determine the size/scale of viewed objects, a compass to determine the sled heading and orientation, and a depth (pressure) sensor. The video signal from the sled is send via a coaxial conductor within a 200 m long and 127 mm diameter umbilical cable to a topside control unit. The video data are recorded to digital video cassette using a video recorder mounted in the control console. Hypack Max (version 2.12A) hydrographic survey software was used to record GPS data, water depth, length of umbilical cable in the water, and camera sled information (height, heading, etc.), which provide ship and camera sled positions for the duration of individual tows. Data Files: Video data were recorded on video tape recorders and the position of the camera sled was recorded using a GPS signal and different software packages, as described above. File naming convention: Each tow is given a name consisting of a 3-letter designator for the island area followed by a two-digit year and three-digit tow number. During SB0401 the consecutive numbers started at SAI04001. Video tape labels and paper log forms are annotated with the tow name. Data recorded using Hypack software follow the Hypack CHS filename format consisting of the year, the first two letters of the platform name, the Julian date, and the hour and minute in which the file was started, and the extension "raw." For example, a file collected on Dec. 10, 2004 (Julian date 345) aboard the Carolinian starting at time 1935 would be 2004CA3451935.raw. Time Correlation: All times are based on UTC. Clocks were manually synchronized prior to starting data collection each day of operations. Resource Description: Digital video imagery that is geo-referenced to navigation files.
ground condition
Please acknowledge the NOAA Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center as the source of this information.
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NMFS/PIFSC/CRED
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Benthic Habitat Mapping Group, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA
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The horizontal position accuracy for the camera sled position is estimated at plus or minus 100 meters. There are two primary sources of this error. The ship's positioning is based on GPS SPS, often called standalone or non-differential GPS positioning. SPS has a measured accuracy of under 5 meters. The position of the GPS antenna is referenced to the ship's granite block. The second and larger primary source of error is the uncertainty associated with the sled's position as determined by using a complex algorith with inputs as the ship's position, a predetermined average layback value, based on the cable out reading to calculate an offset from the ship for every position.
After a tow was completed the video tape data was reviewed by spot-checking the master and backup tape to verify that data were recorded. Raw data files recorded using Hypack Max software include time, horizontal position, and depth information were copied from the acquisition computer to the data archive. Tow-specific metadata were recorded in the data archive in the same location as the raw data, in a spreadsheet that was then referred to in creating metadata records of each island where data were collected during the cruise. Raw data files were exported as comma-delimited text files which were then imported into ArcGISv9.3 and saved as shapefiles. Additional depth data was extracted from underlying bathymetry using "Extract values to points" tool available in ArcGIS. The dbf of the shapefile was then imported into the TOAD database, which is a custom-built Access 2003 database. The benthic habitat for each tow was classified using the PIBHMC_tow classification scheme. Five points were classified at 30 second intervals and codes were inputted directly into the TOAD database. The classified results were then exported as an excel spreadsheet and imported into ArcGIS v9.3, and then saved as a shapefile. Percent scleractinian coral was colour symbolized in optical validation maps with underlying fields of different substrates contained within the attribute table of the shapefile. For more information on classificiation methods, refer to the PIBHMC website ftp://ftp.soest.hawaii.edu/pibhmc/website/webdocs/documentation/Optical-Proc_Overview.pdf For more information on the classification scheme,refer to the PIBHMC website ftp://ftp.soest.hawaii.edu/pibhmc/website/webdocs/documentation/Benth-Habitat-Class_Codes.htm
These data are not to be used for navigational purposes. NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.
Each comma-delimited record contains informaation on the UTC date and time, horizontal position of the sled, and heading of the ship over the period of time that the camera sled is in the water. List of navigation files: 2010__0450226.RAW 2010__0670004.RAW 2010__0670427.RAW 2010__0700933.RAW 2010__0701152.RAW 2010__0701315.RAW 2010__0710959.RAW 2010__0711039.RAW 2010__0711256.RAW 2010__0711401.RAW 2010__0711528.RAW
13 h of video data are avialable covering 25 km of seabed, recorded on 30 video tapes. List of video tapes: GAL10001, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10001, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10002, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10003, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10004, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10005, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10006, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10008, forward and downward tapes, Mini DV (master) and DVD (backup) SAI10009, forward and downward tapes, Mini DV (master) and DVD (backup) SAI04009, forward and downward tapes, Mini DV (master) and DVD (backup) TFF10001, forward (1 & 2) and downward (1 & 2) tapes, Mini DV (master) and DVD (backup) TFF10002, forward (1, 2, 3) and downward (1, 2, 3) tapes, Mini DV (master) and DVD (backup)
