CRED Optical Validation Data at Penguin Bank on the southwest coast of Molokai, Hawaii, 2005 to Support Benthic Habitat Mapping

Title:

Abstract:

Optical validation data were collected using a Tethered Optical Assessment Device (TOAD), an underwater sled equipped with an underwater digital video camera and lights. Data were collected on Penguin Bank on the southwest coast of Molokai in the main Hawaiian Islands to support Benthic Habitat Mapping efforts.

Supplemental_Information:

Molokai, formed from two extinct volcanoes, covers an area of 673 sq. km and reaches 1515 m at its highest point. Generally situated between Maui and Oahu at 21 degrees 08'N, 157 degrees 00' W, the island has 142 km of shoreline and an estimated 998 sq. km of reef (Hawaii Coral Reef Network). The island is one the four members of the Maui Group (also including Maui, Lanai and Kahoolawe), situated together on a shallow, submerged bank. In the recent geological past, the islands formed a single land mass (Maui Nui) during periods of lowered sea levels. Like all of the main Hawaiian islands, it is considered a high island and contributes significant nutrient and sediment runoff to coastal waters. Molokai's human population was counted at 6,717 in 1990, mostly scattered around the island. There are no designated marine protected areas around Molokai, although the Hawaiian Islands Humpback Whale National Marine Sanctuary spans 3642 sq. km of the waters among and around the Maui Group. Penguin Bank is a flat-topped feature with a surface area of 1015 sq. km that extends from the west coast of Molokai approximately 70 km to the southwest. Optical validation data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video camera and lights. These data are used to provide ground-truth validation that for benthic habitat maps based on multibeam echosounder surveys. A limited number of camera sled tows were conducted, to further investigate specific features identified during multibeam surveying. The camera sled was deployed from lower arm of the starboard J-frame on the NOAA Ship Hi'ialakai. At each station the ship was positioned with the wind on the starboard side and drifted downwind; occasional light turns were applied to the ship's screws if necessary to reduce the ship's motion. The TOAD was lowered slowly to the bottom by the deck crew. The 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. The operator continued to monitor the vehicle and provided commands to raise or lower it to keep the camera just above the bottom.

Equipment Description: The TOAD was deployed from the lower arm of the vessel's J-frame. The TOAD is a camera sled based on the Guildline MiniBat model 8820 tow body. The frame has been extensively modified from its original configuration and was configured with a single ROS model 54-00100-13 color underwater video camera and two 500 W DeepSea Power & Light model 710-0400601 underwater lights mounted on the original sled frame. The MiniBat pressure sensor and wing controller was also mounted on the frame but no wings were installed. Cable between the sled and the surface consisted of an underwater electrical cable (cable 1, blue in color) with a separate load-bearing line to support the sled frame. The electrical cable was clipped to the line at regular intervals upon deployment and removed upon recovery. The load-bearing line was led to the starboard capstan on the aft deck. All TOAD surface components were located in the Dry Lab in an equipment rack on the after bulkhead.

Name & address of person collecting data: John Rooney NOAA IRC NMFS/PIFSC/CRED 1845 WASP Blvd., Building 176 Honolulu, HI 96818

Data Files: Video data were recorded on two video tape recorders. The position of the camera sled was recorded using Hypack Max version 02.012a survey software.

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. For example, during HI0504 the first tow was called MOL05000. Video tape labels and paper log forms are all annotated with the tow name. Data files recorded in Hypack software followed their 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. For example, a file collected on July 18, 2005 (Julian date 199) aboard the Hi'ialakai starting at time 1935 would be 2005HI1991935.

Time Correlation: All times are based on UTC. Three clocks were manually synchronized prior to starting data collection; the clock in the video character generator that was used to annotate the video tape, in one of the video cassette recorders, and in the computer running the Hypack Max software. These clocks were set to UTC at the beginning of each evening's operations.

Resource Description: Digital video images that are geo-referenced to navigation files.

Data format:	Each comma-delimited record contains year, day of year, time, latitude, longitude, velocity north and east, water column depth, vehicle depth, layback, and wing angle. For this data set the fields for vehicle depth and wing angle do not contain useful data. List of navigation files: 2005HI180838.RAW 2005HI1802005.RAW 2005HI1802143.RAW 2005HI1802209.RAW 2005HI1802257.RAW in format ASCII
Media you can order:	CD-ROM (format ISO 9660)

Data format:

Each comma-delimited record contains year, day of year, time, latitude, longitude, velocity north and east, water column depth, vehicle depth, layback, and wing angle. For this data set the fields for vehicle depth and wing angle do not contain useful data. List of navigation files: 2005HI180838.RAW 2005HI1802005.RAW 2005HI1802143.RAW 2005HI1802209.RAW 2005HI1802257.RAW in format ASCII

Media you can order:

CD-ROM (format ISO 9660)

Data format:	List of Video tapes: MOL05000 MOL05001 MOL05002 MOL05003 in format mini digital video
Media you can order:	Video casette tape (format Mini DV)

Data format:

List of Video tapes: MOL05000 MOL05001 MOL05002 MOL05003 in format mini digital video

Media you can order:

Video casette tape (format Mini DV)

CRED Optical Validation Data at Penguin Bank on the southwest coast of Molokai, Hawaii, 2005 to Support Benthic Habitat Mapping

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