Expedition update: Agincourt Reef

On our final day of expedition we surveyed the northern most reef of Agincourt No.5. We began the day surveying the front reef where we noticed that apart from the hard and soft corals present, much of the benthic cover consisted of coralline algae. It has been found that the chemical cues from coralline algae induce coral recruitment, while substrate covered in macroalgae or turf algae deters coral recruitment or smothers the coral recruit. On our second dive, as we entered the more sheltered section of the reef we came across the nesting grounds of Yellow Margin Triggerfish. The male triggerfish were busying themselves with their nests, creating rounded depressions in the sand and placing pieces of coral rubble within them. Pretty soon the females would be coming to inspect these nests and choose their mate. Once the females lay their eggs, they protect these nests ferociously. They are famous in the dive community for charging and biting divers that crossed into their nesting territory, which extend up and outwards from the nest similar to an inverted cone shape.