Surveyed 14 January 2015.
The first flank of Reef 20-104 is partly exposed to the prevailing wind and sea conditions found within the lagoon of the Great Barrier Reef. Manta tow surveys were conducted on the reef slope. The reef slope is generally steep dropping off into approximately 20m of water to a gently sloping reef base composed mainly of sand, rubble, reef framework and hard coral. The reef structure has few features including gullies and overhangs.
The benthic community was dominated by coralline/turf algae, but hard coral was also common. Hard coral cover on the reef first flank was high with no one coral genus dominant. The dominant coral lifeform was encrusting, but other forms such as tabulate, branching, massive, sub-massive and foliose corals were also present in decreasing order of abundance. Coral bleaching was present on a few individual colonies.
The fish abundance on the first flank of Reef 20-104 was high. Conspicuous groups of reef fishes included baitfish, fusiliers, parrotfish, surgeonfish and damselfish. No crown-of-thorns starfish were observed on the first flank of Reef 20-104 .