Key environmental pressures
Above average summer sea temperatures were the greatest environmental influence for inshore corals over the 2019-20 summer. It was much warmer than the preceding year.
No major cyclones made landfall and there was less rainfall in the catchment and less river discharge flowing into the Reef than average. This was a welcome reprieve after major flooding in and around Townsville and further north the year before.
How did inshore corals respond?
- Inshore corals remained in an overall ‘poor’ condition, primarily due to storms and above average sea temperatures. Some signs of recovery were observed, with both coral cover and juvenile density increasing at some locations.
- Above average seawater temperatures caused widespread coral bleaching. Although many inshore reefs bleached (especially in the Burdekin and Fitzroy regions) the coral mortality observed in mid-2020 was low. This is an encouraging sign, as not all bleached corals die, they can also recover if conditions are favourable.
- Since 2016, cumulative pressures have contributed to coral decline across the inshore Reef (trends vary within regions):
- Corals in the Wet Tropics, Burdekin and Fitzroy region have shown an ability to recover. Last year, reefs in the Wet Tropics remained in a moderate condition with a stable trend. Coral in the Burdekin and Fitzroy continued to improve, remaining moderate and poor respectively
- In contrast, coral remained poor and continued to decline in the Mackay-Whitsunday since 2017, following cyclone Debbie.
- Impacts from storms and elevated sea temperatures, and effects of poor water quality, especially during high rainfall years, are influencing the condition and recovery of inshore corals.
What is monitored and where?
Condition and trend of inshore coral reefs is surveyed at two depths – 2m and 5m for:
- coral cover
- proportion of macroalgae
- juvenile coral density
- rate at which coral cover changed
- coral community composition
- physical scars, bleaching, disease and other damage.
How do we monitor?
Divers survey between fixed points on the seafloor and:
- photograph coral and other marine life
- record the amount of coral cover, its condition and the coral type
- search for scars, bleaching, disease or other damage.
Most monitoring occurs between May-July. This allows coral to react to the impacts occurring in the previous summer, such as cyclones and bleaching events.
Would you like more detail?
- AIMS Data Centre has reef monitoring survey results
- Detailed annual reports are in the Publications e-Library
- View the Inshore coral sampling locations 2019-20.