Cyclone damage - coral breakage

Cyclone damage - excavation

Cyclone damage - excavation

Cyclone damage - matrix exfoliation

Cyclone damage - rubble filled gutters

Cyclone damage - torn soft coral

Tropical Cyclone Larry (TC Larry) crossed the north Queensland coast near Innisfail on 20 March 2006. TC Larry was classified as a category 4-5 cyclone when it crossed with wind gusts up to 290 km/hr, and was the most severe cyclone to cross the Queensland coast in 100 years. TC Larry generated a band of ‘very destructive’ winds, between Cairns and Tully, with recorded winds up to 180 km/hr. To the north, ‘destructive’ winds were experienced between Cairns and Cape Tribulation and to the south, ‘destructive’ winds were experienced between Tully and the Hinchinbrook/Cardwell region.

To assess the impact of TC Larry, the Research and Monitoring Coordination Unit inspected eight reefs between Townsville and Cairns (between latitudes 17º and 19º South). These reefs lie perpendicular to TC Larry’s track and represent exposure to a variety of wind strengths. Reefs were surveyed using the ‘manta tow’ method, and where time and conditions permitted, detailed assessments were conducted by snorkel or SCUBA. While all reefs were surveyed for cyclone damage, poor weather conditions prevented assessment of all parts of each reef, in particular, the weather front of the reef.  

In general there was less damage then expected. This is likely to be due to that fact that TC Larry was small in diameter and was travelling relatively quickly, therefore not hovering over any one area for any length of time. The most common signs of impact included damage to the underlying reef structure, broken and dislodged corals and movement of coral rubble and debris. The majority of the reefs surveyed had experienced previous damage through crown-of-thorns starfish outbreaks. Consequently, coral cover was at low levels before TC Larry affected these reefs, and most of the observed impact was damage to the reef structure rather than damage to living corals.

This initial assessment will be followed up with a more comprehensive survey by the Australian Institute of Marine Science (AIMS) later in the year.