Assessing habitat damage caused by the grounding of the Shen Neng 1 on Douglas Shoal, southern Great Barrier Reef, using towed video (Towvid)

Towed video (Towvid) was deployed on eight occasions over a two day period (17-18 April, 2010) on Douglas Shoal. Sites included the initial grounding site of the Shen Neng 1, on the south east edge of the Shoal, the final grounding site and a randomly selected unimpacted site on the same shoal but a minimum of 1050 m from the ship's path.

Initially, it was envisioned that the multibeam sonar bathymetry survey would generate real time high resolution topographical imagery to guide the Towvid survey. However, rough conditions on the voyage meant that post-survey analysis was required to reduce signal noise. Therefore, the path of the stern of the Shen Neng 1, together with the lay of the ship (provided by GBRMPA), was used and tows were planned to intercept and traverse areas where damage was likely to have occurred from contact of the ship's hull on the shoal along with areas of shoal not affected by the grounded ship.

A towed camera system incorporating a standard definition video camera and digital stills camera was deployed to recover imagery of the benthos. A computer-based application (Towvid), developed by AIMS, allowed for real-time classification of substrata, benthos and individual organisms. Data points were recorded at 2-second intervals or on demand when a new substrate, benthos or organism was observed.

Habitats were classified based on the substrata (4 categories) and overlying epibenthos (8 categories) and individual organisms (4 categories) viewed on the tapes.