Fig 1.
Spatial extent of TC Yasi with wind zone boundaries.
(a) Satellite-based photograph of TC Yasi on February 2, 2011 prior to crossing the Queensland coast between Townsville and Cairns on February 3 (images courtesy of the Australian Bureau of Meteorology (BoM)). (b) Boundaries of gale force, destructive and very destructive winds from BoM; the extent of gale force winds north to south along the GBR exceeded 600 km.
Fig 2.
TC Yasi survey reef locations (surveyed February 10 to March 17, 2011 and from January 1 to September 30, 2013).
Bar charts for each 50-km Marine Park segment north and south of the track of TC Yasi represent the proportion of surveys that recorded each of 5 levels of damage (n = 841). Locations in red denote reefs where ≥60% of the surveys recorded structural damage (level 4 or 5) and the two labeled reefs are the locations in Fig. 8. Locations in blue were surveyed during both 2011 and 2013. See Figs. 3 and 4 for damage level descriptions.
Fig 3.
Damage extent and severity scores in light blue represent the survey area damaged (Damage extent) and the dominant type of colony-level damage observed (Damage severity description). Damage levels 1, 2 and 3 relate to coral damage, while 4 and 5 relate to reef structural damage (see colour scale on right). Representative photographs of each damage level are shown in Fig. 4 with damage descriptions.
Fig 4.
Representative photos of the 5 damage levels used in the impact assessment and analysis.
The damage levels used follow the matrix in Fig. 3, which combines damage extent with the dominant type of colony-level damage observed.
Fig 5.
Potential for structural damage (very low to high) of GBR coral communities from tropical cyclones (TCs, 1985–2014).
The 44 TCs are plotted on the diagram with respect to their intensity along the horizontal axis and their circulation size along the vertical axis. Of the 7 TCs that were large, only TC Yasi was also intense and posed a high risk of structural damage.
Table 1.
Total and percentage reef area affected within each damage level.
Fig 6.
Photos taken within 50 m showing the patchiness of damage at Bramble Reef in the very destructive wind zone and Dip Reef in the destructive wind zone.
See Fig. 1 for destructive and very destructive wind zone boundaries and Fig. 2 for reef locations.
Fig 7.
Average damage severity (with 95% confidence intervals) in each of the surveyed 50 km segments of the Marine Park (see Fig. 2, surveys February-March, 2011).
The percent of reef with structural damage (damage level of 4 or 5, Figs. 3 and 4) is also shown (±SE). The cyclone symbol denotes the location of the track of the cyclone eye.
Fig 8.
Proportion of surveys that recorded each level of cyclone damage at mid-shelf and outer-shelf reefs within each 50 km segment (Fig. 2) of the Marine Park.
Fig 9.
Changes in benthic cover between 2011 and 2013 based on recovery surveys from a sub-set of reefs surveyed 150 km north to 100 km south of the cyclone track (Fig. 2 for reef locations).
(a) Proportion of the benthos made up by live coral, recently dead coral, live coral rock, coral rubble, sand and macroalgae. (b) Positive (increasing) and negative (decreasing) percent changes between 2011 and 2013 are shown for each benthic cover category. Average values for change presented in (b) are shown in the table for each segment and benthic cover category with standard deviation values in brackets. Photographs on the right show (c) algae blooms following TC Yasi in 2011, (d) the transition from recently dead coral to live coral rock, and (e) coral recruitment and recovery at Helix Reef.