Adult trochus inhabit intertidal and shallow (less than 5 m depth) areas of tropical coral reefs that receive strong wave or tidal action. In the King Sound Region they are often found on hard reef surfaces dominated by short algae rather than corals or other attached invertebrates. They are also found around the edges of boulders within the intertidal zone, avoiding areas covered with sand or mud (Nash, 1985). Trochus do not usually occur on sandstone reefs if these lack the three-dimensional matrix structure typical of coral reefs. In contrast, juveniles (less than 50 - 60 mm) tend to inhabit areas of the reef flat zone that have coral rubble or holes in the reef matrix for refuge and small juveniles (less than 30 mm and typically younger than one year) are difficult to find (see Colquhoun, 2001). Results from the recent Australian Centre for International Agriculture Research (ACIAR) trochus reseeding research project indicated that juvenile trochus prefer coral rubble or other hard substrates. Maturing animals are believed to move to the wave-exposed or subtidal fore-reef areas where they reach adult size (Castell, 1997). |