EFFECTS OF TROPICAL CYCLONE WAVES ON ECOLOGICAL AND GEOMORPHOLOGICAL STRUCTURES ON THE GREAT-BARRIER-REEF

Damage to coral reefs caused by Tropical Cyclone Ivor (March 1990) on 46 sites over 150 km of the Great Barrier Reef was patchily distributed within 50 km of the path, while at distances >50 km from the eye, it was uniformly low. These distances suggest that local wind-generated waves, not ocean swells, may be the major cause of destruction. Wind component incident on each site, U(N), was therefore hindcast from tropical cyclone circulation models. The sum of hourly U(N) explained about 82% of the variance in an index of total damage and 90% of the destruction of a veneer of dense coral growth up to 1.5 m in thickness. This correlation is consistent with an "attrition" model, in which cyclone waves exfoliate reefs, chunk by chunk, over the period of storm waves.