A total of 365 towed video transects were completed in the 2006/2007 surveys. The sampling has identified a vast array of habitats and will be used for broad scale mapping of benthic communities in the marine park, however further transect tows will be conducted in 2008 in areas of special interest, where sampling is considered limited and where ground-truthing is required. Towed video sampling effort was concentrated around Mandu, Osprey, Yardie, Winderabandi and Point Cloates in 2006. In 2007, to ensure adequate sampling effort throughout the marine park, sampling was stratified at 5 km intervals from Point Murat to Red Bluff conducting 3-4 transects from the back of the reef out to the seaward marine park boundary at each point.
Towed video allows for the visualisation of the range of benthic communities occurring within the marine park, ground truthing of areas with significant bathymetric and textural properties and provides detailed information on the variability in diversity, abundance and biomass of all the different communities.
Visual imagery of the benthos was captured using a 1/3 inch single CCD colour video camera mounted on a Para vane and controlled by a winch with 320m of electromechanical cable. Two 12 volt, 35 watt underwater lights illuminated the field of view. The video signal was recorded on a shipboard miniDV tape recorder. In addition to the visual imagery the miniDV tape recorder received GPS data (latitude and longitude, ground speed, true heading, date and time), which was recorded on the audio track. A computer-based application (TowVid), developed by AIMS (Speare et al. 2004), allows for real-time touch-screen classification of substrata, benthos and individual organisms interfaced with a GPS to facilitate real-time geo-referencing of all data points. C-MapTM vector charts and MaxseaTM electronic navigation software were used to record the ship's track and water depth. Data points were recorded at 8-second intervals or on demand when a new substrate, benthos or organism was recorded on TowVid. An average speed of 1.5 knots was achieved over the Towed Video surveys equating to a horizontal resolution of 6m.
