Tutuila is the largest of seven islands in American Samoa at 142.3 sq. km. Volcanic in origin, it reaches a height
of 653m at Matafao Peak. Tutuila is centered at 14.30?N, 169.75?W, has 101.3 km of coastline and an estimated 36.2
sq. km of reef area. The port of Pago Pago is a collapsed crater and is one of the largest natural ports in the
Pacific. Pago Pago contains a tuna cannery which is a hub of a large purse-seining tuna fishing fleet. The cannery
outputs large amounts of nutrients as byproduct into the waters of Pago Pago harbor. The human population of Tutuila
in 1990 was 45,043. It is considered a high island and contributes significant nutrient and sediment runoff to
coastal waters. Tutuila's waters are protected by the 0.7 sq. km Fagatele Bay National Marine Sanctuary, as well as
by the National Park of American Samoa, which covers the north-central part of the island and approximately 5 sq. km of coastline.
Optical validation data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with
underwater video camera, still camera, and lights. These data are used to provide ground-truth validation for
benthic habitat maps based on multibeam echosounder surveys. Camera sled deployments were conducted at night,
usually between 1800 and midnight. The TOAD was deployed from a pot hauler mounted on the starboard side of the
fantail on NOAA Ship Townsend Cromwell. It was 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. The TOAD was a MiniBat 8820
unit manufactured by Guideline, and was towed by the ship at 1-2 knots while remotely guided from the ship using
adjustable wing controls to keep the unit close to the underwater substrate. The TOAD was damaged during the cruise
on 02/20/02, and subsequent tows were conducted as drift deployments. 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 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 is a camera sled based on the Guildline MiniBat model 8820 tow body. The frame was
configured with a single Sony DCR-PC110 Digital Video Camera in a modified Gates underwater housing, a Canon Power
Shot G1 Still Camera (modified by CRED engineers) in an Ikelite housing rated to 60 m slaved to an Ikelite DS-50
strobe, and two 500 W DeepSea Power & Light model 710-0400601 underwater lights. The Canon camera had a custom-built
timer that enabled the user to select a constant time interval (ranging from approximately 5 seconds to 2 minutes)
between photographs. An interval of 30 seconds was typically selected, which, assuming a mean velocity for the camera
sled of 1.5 knots, resulted in one photograph approximately every 20 m. Photograph resolution is 2048 x 1536 pixels
and file names are assigned sequentially and automatically by the camera, starting at 100-0000 after the camera's
memory is cleared. The MiniBAT pressure sensor and wing controller were also mounted on the frame but the pressure
sensor was not operational, after damage to the TOAD on 02/20/02. And the sled's wings were not installed thereafter.
The cable between the sled and the surface was an underwater load-bearing electrical cable. The TOAD computers were
located in the Electronics Lab of the Townsend Cromwell. The electronics box containing the power switches was
secured to the ship's fantail, and all other TOAD surface components were secured in the ship's wet lab.
Name & address of person collecting data:
Joyce Miller & Ron Hoeke
1125B Ala Moana Blvd
Honolulu, HI 98614
Data Files: Video data were recorded on two video tape recorders. Still photos were recorded on digital camera and
downloaded to the TOAD computer after the tow. The position of the camera sled was recorded using Guildline MiniBat
In-Tow data acquisition 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, which increments by one for each new tow around that island. During TC0201 (NOAA Ship Townsend Cromwell's
first cruise in calendar year 2005) the consecutive numbers started at TUT02001. For following cruises, the tow numbers
will increment by 100, so the first tow on the next cruise will be tow number 100. Video tape labels, the navigation
(.glo and .shp) files, and paper log forms are annotated with the tow name and number, e.g., TUT02001. If the navigation
file is edited during processing the file name has a suffix `a' added. For example, one of the navigation data files
is named `TUT02001a.glo'. Metadata were extracted from the navigation data and recorded to a file with the same name
as the navigation file except that a file type of `.met' was appended; for example, `TUT02001a.glo.met'.
Time Correlation: All times are based on UTC. Two clocks were set manually synchronized prior to starting data
collection; the clock in the video character generator that was used to annotate the video tape and the TOAD data
acquisition computer clock was used to annotate the navigation (*.glo) files. These clocks were set to UTC at the
beginning of each evening's operations and then compared to one another prior to (and during) each tow. There were
problems maintaining synchronization of the TOAD computer clock during this cruise. See the problems section for a description.
Resource Description: Digital video images that are geo-referenced to navigation files.