GREAT BARRIER REEF
// Outlook Report 2014
Impacts on the ecosystem were most severe in the southern half of the Region, causing significant damage to coral reef habitats, particularly due to cyclone Hamish, in March 2009, which affected more than 50 per cent of the coral reefs in the Region.15,16 In February 2011, cyclone Yasi crossed the Queensland coast, one of the most powerful cyclones to have affected Queensland since records commenced.18,19 Previous cyclones of a comparable intensity include the 1899 cyclone Mahina in Princess Charlotte Bay, and the two cyclones of 1918 at Mackay (January) and Innisfail (March). The damage from cyclone Yasi was extensive. Overall, some level of coral damage was reported in over 89,000 square kilometres of the Region. Approximately 15 per cent of the Region’s total reef area sustained some coral damage and six per cent was severely damaged. Most of the damage occurred between Cairns and Townsville.16 In April 2014, category 5 cyclone Ita entered the northern area of the Region, crossing the coast near Cape Flattery. The impacts of cyclone Ita were being assessed at the time of writing. Wind also plays a role in the marine ecosystem; in Category 5 cyclone Yasi affected much of the central Great Barrier Reef in February 2011 particular, it can cause substantial changes in the Source: Satellite image originally processed by the Bureau of Meteorology from the shape of islands and coastlines and can affect ocean geostationary meteorological satellite MTSAT-2 operated by the Japan Meteorological Agency currents.4 There is emerging evidence of increases in wind strength Australia-wide, but little information specific to the Region.20 Changes in wind patterns may There is emerging evidence of have consequences for inshore ocean turbidity through resuspension of sediments21; island formation22; 23 increases in wind and the distribution of planktonic larvae . Warming sea temperatures have implications for cyclones and 24 strength Australiawind (see Section 6.3.1).
3.2.3 Freshwater inflow
The rivers and streams flowing into the Region drain an area of 424,000 square kilometres along the east coast of Queensland — the Great Barrier Reef catchment. There are six major natural resource management catchment regions: Cape York, Wet Tropics, Burdekin, Mackay Whitsundays, Fitzroy, and Burnett Mary. While the Wet Tropics rivers (from Ingham to about Port Douglas) deliver water to the Region almost all year, in other catchments there is little or no flow most of the time, interspersed with major floods usually during the summer monsoon season and on decadal timescales.25 In the Outlook Report 2009 it was reported that the flow of freshwater from 2004 to 2007 was significantly lower than the long-term average.1 Since that time, increased annual rainfall and floods have resulted in much greater volumes of freshwater entering the Region (Figure 3.3). Between 2008 and 2012 higher than average annual freshwater discharges were recorded for many of the major rivers, especially in southern catchments.26
Large volumes of freshwater flowed into the Region in the past five years, including some record flows.
Figure 3.3 annual freshwater discharge from major rivers, 2002–2013
Resources and Mines (Qld) compiled by the Australian Institute of Marine Science 201226 and McKenzie et al. 2014 33
Much greater volumes of freshwater entered the Great Barrier Reef lagoon between 2008 and 2012 compared to previous years. The annual discharges from the major rivers are combined for each natural resource management region. Each year is shown in a different colour and represents the discharge for the 12-month period starting in October. Source: Data supplied by Department of Natural