Reef Health update | 16 April 2025

During the 2024–25 summer, the Reef has been exposed to a combination of pressures — above average water temperatures, flood plumes and crown-of-thorns starfish outbreaks, on top of multiple pressures from the 2023–24 summer.

These findings have been detailed in the Reef snapshot: summer 24–25 released today by the Reef Authority in collaboration with science partners the Australian Institute of Marine Science and CSIRO.

Temperature and rainfall

Sea surface temperatures across the Marine Park are forecast to drop to around 0.5°C above the long-term averages in May — below levels expected to cause further coral bleaching.

However, they are currently unseasonally high — between 1.3°C and 2.1°C above the long-term regional averages (from 2 to 8 April).

The Bureau of Meteorology forecasts around average rainfall over Marine Park catchment areas for the rest of April and into May.

Reef health

As referenced in the Reef snapshot: summer 2024–25 the Reef this summer experienced:

• Results of aerial surveys and in-water monitoring to date suggest the Reef has experienced widespread coral bleaching across the Far Northern and Northern regions of the Marine Park —mostly a result of prolonged exposure to higher-than-average water temperatures.
• This event is the sixth since 2016 and, while less extensive than the coral bleaching event in 2023–24, it is the second time the Reef has experienced widespread bleaching events across consecutive summers.
• The coral bleaching observations this year are consistent with the patterns of heat stress and flood plumes seen across the Reef over the summer months between Mackay and the top of Cape York.
• Record rainfalls led to flooding in the Northern and Central regions, causing some freshwater coral bleaching and coral mortality on some inshore reefs.
• Climate change is the greatest threat to reefs worldwide. This summer closely follows the disturbance events from 2023–24, affecting the Reef’s opportunity to recover. It will take time to fully understand the extent and implications of these compounding climate-driven events. 

A total of 380 in-water Reef Health Impact Surveys (RHIS) were conducted across the Marine Park from 27 March to 10 April. Various coral bleaching was reported on 19 of the 33 reefs surveyed (58%).

• Northern region: most surveyed reefs had low-level (1-10%) coral bleaching prevalence*, with some reports of medium (11-30%) to high-level (31-60%).
• Central region: most reefs had no coral bleaching, low (1-10%) or medium (11-30%) coral bleaching prevalence.
• Southern region: either no or low (1-10%) coral bleaching prevalence were recorded in the Southern region. 
• Far Norther Region: No in-water reports were available during this period.

The Crown-of-thorns Starfish (COTS) Control Program and Reef Joint Field Management Program have surveyed and undertaken culling at 187 reefs this financial year. As a result, these predator starfish are at sustainable levels for coral growth and recovery on 112 of these reefs (60 per cent).

Outbreaks of Crown-of-thorns Starfish are impacting reefs throughout the Marine Park but are most severe in the Southern region (Swains Reefs) and between Port Douglas and Lizard Island. Cull operations are underway at 43 reefs to suppress starfish outbreaks.

Reef management

Reef Authority and Queensland Parks and Wildlife Service staff, as part of the Reef Joint Field Management Program, have completed dedicated in-water surveys between Rockhampton and Yeppoon (Capricorn Bunker Group). Results are being analysed to assess impacts from heat stress and flood plumes on coral reef communities, as well as tropical cyclone Alfred.

The Reef Authority partners with the tourism industry, government, science, and university data collectors to ensure access to the most up-to-date data across the World Heritage Area.

Our management actions build and support Reef resilience and include enforcing compliance with the Reef’s zoning plan and ensuring people are enjoying the Reef in a responsible way.

*Prevalence is the proportion of coral cover (averaged for each surveyed reef) affected by coral bleaching.

Reef Health update | 09 April 2025

We are currently evaluating aerial and in-water surveys from the Northern parts of the Reef and whether ex-Tropical Cyclone Alfred affected reefs on the outer edges of the southernmost part of the Marine Park.

A summary of the combined aerial and in-water survey results will be presented in the Summer Reef Snapshot.

A comprehensive analysis of trends in coral condition will be provided by the Australian Institute of Marine Science's Long-Term Monitoring Program and the Reef Authority’s Marine Monitoring Program later this year.

Temperatures

While sea surface temperatures remain above the long-term averages across the Reef, they are forecast to drop, over the autumn months, below levels expected to cause further heat stress.

Over the period 27 March to 3 April sea surface temperatures averaged 29.6°C in the Far North, 28.9°C in the North, 28.2°C in the Central region and 27.8°C in the South. 

Rainfall

The Bureau of Meteorology forecasts above average rainfall for Northern and Central Queensland in the coming week. This could lead to continued freshwater intrusion in the Marine Park for the Far Northern, Northern and Central regions. 

Reef health

A total of 449 in-water Reef Health and Impact Surveys (RHIS) were conducted across the Marine Park in the fortnight from 20 March to 3 April. Coral bleaching was reported on 34 of the 42 reefs surveyed (81%).

• Northern region: most surveyed reefs had low-level (1-10%) coral bleaching prevalence*, with some reports of medium (11-30%) to high-level (31-60%).
• Central region: most reefs had no coral bleaching, low (1-10%) or medium (11-30%) coral bleaching prevalence.
• Southern region: either no or low (1-10%) coral bleaching prevalence were recorded in the Southern region. 
• Far Norther Region: No in-water reports were available during this period.

The Crown-of-Thorns Starfish (COTS) Control Program and Reef Joint Field Management Program have actioned 187 reefs for surveillance and culling of the coral-eating crown-of-thorns starfish so far this financial year (to 14 March). The program provides valuable information on Reef condition and impacts such as temperature stress and flood plumes. Importantly, it protects coral cover.

Crown-of-thorns starfish outbreaks are impacting reefs throughout the Marine Park but are most severe in the Southern region (Swains Reefs) and between Port Douglas and Lizard Island. Cull operations are currently active at 43 reefs to suppress starfish outbreaks and protect coral.

COTS are at sustainable levels for coral growth and recovery on 112 of the 187 actioned reefs (60%).

Reef management

Reef Authority and Queensland Parks and Wildlife Service staff, as part of the Reef Joint Field Management Program, have completed dedicated in-water surveys between Rockhampton and Yeppoon (Capricorn Bunker Group). Results are being analysed to assess impacts from heat stress and flood plumes on coral reef communities, as well as ex-Tropical Cyclone Alfred.

The Reef Authority partners with the tourism industry, government, science, and university data collectors to ensure access to the most up-to-date data across the World Heritage Area.

Our management actions build and support Reef resilience and include enforcing compliance with the Reef’s zoning plan and ensuring people are enjoying the Reef in a responsible way.

*Prevalence is the proportion of coral cover (averaged for each surveyed reef) affected by coral bleaching.

Reef Health update | 03 April 2025

In-water surveys to assess the impacts from heat stress and flood plumes are continuing with the Reef Joint Field Management Program team recently completing surveys of coral communities between Innisfail and Cooktown.

The Capricorn Bunker Group will be the focus of the in-water surveys in early April, with teams assessing the impacts of tropical cyclone Alfred.

Results from the aerial and in-water surveys are being processed and will be released in the Summer Reef Snapshot.

Sea surface temperatures have remained relatively stable across the Marine Park, with a slight increase in the Far Northern region, and slight decreases in the Northern and Central regions.

Temperatures

This week sea surface temperatures in the Far Northern region have increased by 0.1°C to 1.4°C above the long-term average for March while decreasing relative to the March average in both the Northern region, by 0.1°C to 0.9°C, and Central region, by 0.1°C to 0.7°C. Temperatures remained stable at 0.8°C above the March average in the Southern region.

Sea surface temperatures across the Marine Park are forecast to remain between 0.7°C to 1°C above the long-term average for April.

Rainfall

The Bureau of Meteorology forecasts above average rainfall exceeding 100 mm for some catchment areas inshore of the Far Northern and Northern regions of the Marine Park during the next week. Rainfall totals should ease in the following week, although they are still forecast to be above average for April.

This could lead to continued flooding and freshwater intrusion in the Marine Park for the Far Northern and Northern regions. However, rainfall is forecast to be lower than usual over Far Northern and Northern Marine Park catchment areas in May.

Reef health

During the past fortnight (13–27 March), 261 Reef health impact surveys were conducted across the Marine Park with some bleaching detected on 23 of the 28 reefs (82%) surveyed.

Most reports from the Northern region were of low-level bleaching (1-10% prevalence), with some reports of medium (11-30% prevalence) to high-level (31-60%) bleaching.

In the Central region, most reports were of low (1-10% prevalence) to medium-level (11-30% prevalence) bleaching. No bleaching or low-level (1-10% prevalence) bleaching was reported

from reefs in the Southern region. No in-water data were available for the Far Northern region during this survey period.

Crown-of-thorns starfish are at sustainable levels for coral growth and recovery on 112 of the 187 reefs targeted for culling (60%).

Outbreaks of these coral-eating starfish are impacting reefs throughout the Marine Park but are most severe in the Southern region (Swains Reefs) and between Port Douglas and Lizard Island. Cull operations are currently active at 43 reefs to suppress COTS outbreaks and protect coral.

Reef management

The Reef Authority works closely with the Queensland Parks and Wildlife Service as key data collectors in the Reef Joint Field Management Program as well as academic and management institutions and contractors to ensure access to contemporary data across the World Heritage Area.

Our management actions are geared towards building and supporting Reef resilience, including enforcing compliance with the Reef’s zoning plan and ensuring people are enjoying the Reef in a responsible way.

Reef Health update | 27 March 2025

Aerial surveys to date indicate coral bleaching is widespread but highly variable in the shallows of reefs across the Northern and Far Northern regions of the Great Barrier Reef Marine Park. Preliminary in-water surveys indicate there is also low levels of coral bleaching on surveyed reefs in the Central and Southern regions.

Aerial and in-water reports of coral bleaching are largely consistent with patterns of heat stress seen across the Reef with the Southern region comparatively unaffected by impacts from floodwaters and elevated sea surface temperatures.

Some central areas of the Reef have been impacted by flood plumes that reduced salinity levels causing coral bleaching and in the worst affected areas caused mortality on shallow-water corals at several inshore reefs, particularly in the Palm and Family Islands groups.

Results from the aerial and in-water surveys are being processed and will be released in the Summer Reef Snapshot next month. 

Temperatures

While sea surface temperatures are forecast to remain around 1°C above the long-term average for April, they are no longer at levels expected to cause further heat stress.

Over the past week, sea surface temperatures in the Far Northen region increased to 1.9°C above the long-term average for March. Sea surface temperatures have increased by 0.5°C to 1.2°C above the March average in the Northern region and have decreased slightly to be 0.7°C above the March average in the Central region. In the Southern region, temperatures increased by 0.4°C to 1.2°C above the March average.

Rainfall

The Bureau forecasts above average rainfall for North Queensland in the coming week. This could lead to continued flooding and freshwater intrusion in the Marine Park for the Far Northern, Northern and Central regions. Rainfall is forecast to be higher than usual over all Marine Park catchment areas in April, potentially further reducing sea surface temperatures.

Reef health

A total of 440 in-water Reef Health and Impact Surveys (RHIS) were conducted across the Marine Park in the fortnight from 6 to 20 March. Coral bleaching was reported on 23 of the 31 reefs surveyed (74%).

This including mostly low (1–10% prevalence) to medium-level (11-30% prevalence) coral bleaching in the Northern region. Reports of either no coral bleaching or low-level bleaching (1–10% prevalence) were received from the Central and Southern regions. No in-water data were available for the Far Northern region during this survey period.

Targeted in-water surveys conducted at eight reefs between Townsville and Airlie Beach revealed very low to medium-level bleaching, with mortality due to flood impacts present on the shoreward shallows of one reef located near the Burdekin River mouth. The remainder of the reefs had very low levels of mortality.

The Crown-of-Thorns Starfish (COTS) Control Program and Reef Joint Field Management Program have actioned 187 reefs for surveillance and culling of the coral-eating crown-of-thorns starfish so far this financial year (to 14 March). The program provides valuable information on Reef condition and impacts such as temperature stress and flood plumes.

Crown-of-thorns starfish outbreaks are impacting reefs throughout the Marine Park but are most severe in the Southern region (Swains Reefs) and between Port Douglas and Lizard Island. Cull operations are currently active at 43 reefs to suppress starfish outbreaks and protect coral.

COTS are at sustainable levels for coral growth and recovery on 112 of the 187 actioned reefs (60%). 

Reef management

Over the coming week, Reef Authority and Queensland Parks and Wildlife Service staff, as part of the Reef Joint Field Management Program, will conduct in-water surveys between Innisfail and Cooktown to assess impacts from heat stress and flood plumes on coral reef communities.

The Reef Authority and COTS control program partners are meeting later this week to refine cull targeting to maximise the protection of coral habitats including those affected by coral bleaching, flood, and cyclone damage over the past two years.

The Reef Authority continues to partner with the tourism industry, government, science, and university data collectors to ensure access to the most up-to-date data across the World Heritage Area.

Our management actions build and support Reef resilience and include enforcing compliance with the Reef’s zoning plan and ensuring people are enjoying the Reef in a responsible way. 

Reef Health update | 20 March 2025

The aerial surveys we conducted with the Australian Institute of Marine Science revealed varying levels of shallow water coral bleaching on surveyed reefs between Townsville and the tip of Cape York.

Impacts from flooding were also detected in the shallows of some reefs, mostly offshore Ingham and Innisfail where there were high levels of flood plume exposure.

The aerial surveys were focused on the Far Northern, Northern and Central regions of the Marine Park, which had the greatest exposure to thermal stress and rainfall driven flood plumes.

Survey flights were not conducted across the southern region where heat stress and flooding has been comparatively less.

Detailed analysis of the aerial survey data is underway.  

Temperatures

Clear weather across the Marine Park early last week increased sea surface temperatures, that then decreased with the onset of cloud and thunderstorm activity off the northern and central Queensland coast.

Cloud cover and thunderstorms are forecast to continue in the week ahead, potentially leading to further decreases in sea surface temperatures across the Marine Park. 
  
Over the past week, in the Far Northern region sea surface temperatures remained at 1.3°C above the long-term average for March. Across all other regions, sea surface temperatures increased above the March average — by 0.3°C to 1.2°C in the Northern region, by 0.1°C to 0.8°C in the Central region, and 0.3°C to 0.9°C in the Southern region.

Across the Marine Park, sea surface temperatures are forecast to remain 0.7°C to 1°C above the long-term average for April.

Rainfall

In the coming week, the Bureau of Meteorology forecasts many areas of the Marine Park catchment will receive more rain than usual for late March. While this will likely have a cooling effect, it could also lead to further flooding and freshwater intrusion to the Marine Park.

Reef health

The Reef Authority partnered with its Australian Institute of Marine Science colleagues to conduct aerial surveys across the Far Northern, Northern, and Central regions of the Marine Park— from Cape York in the north to Townsville in the south.

The coral bleaching observed by the aerial surveys was variable across the regions – with some reefs exhibiting no evidence of coral bleaching, while most ranged from low to high levels of coral bleaching. There was little evidence of extreme coral bleaching. The higher levels of coral bleaching were more frequently recorded on reefs surveyed near Princess Charlotte Bay in the Far North of the Marine Park.

Aerial and in-water observations of flood impacts to shallow coral reef communities indicate significant impacts to inshore habitats between Innisfail and Townsville.

The Reef Authority will conduct in-water surveys in the Northern, Central, and Southern regions over the next month, with a focus on assessing the impacts of heat stress and flood impacts.

During the past fortnight —February 27 to March 13 — 270 in-water Reef Health Impact Surveys were conducted across the Marine Park. Mostly lower-level coral bleaching was reported at 24 of the 30 reefs surveyed. Reports of either no coral bleaching or low-level prevalence (1-10%) were received from the Central and Southern regions. Most reports of coral bleaching from the Northern region were of low (1-10%) to medium-level (11-30%) prevalence.

Reef management

Information from in-water and aerial surveys is still be analysed and will be presented in the Summer Reef Snapshot in the coming weeks once analysis is complete.

The Reef Authority, Queensland Parks and Wildlife Service, and many other organisations are working hard to support Reef resilience, including enforcing compliance with the Reef’s zoning plan, controlling crown-of-thorns starfish outbreaks, and taking action to minimise catchment runoff into the Reef. 

Reef Health update | 12 March 2025

Sea surface temperatures remain above average in the Marine Park, while the February low-pressure systems did provide temporary relief, heat stress across much of the Reef has started to accumulate this past week.

To better understand the impact of the summer heat stress and flood plumes the Reef Authority, in partnership with the Australian Institute of Marine Science (AIMS) are currently conducting aerial surveys in the Far Northern and Northern regions.

Temperatures

Over the past week, sea surface temperatures increased in the Far Northern region to 1.1-degrees above average, while temperatures remained steady in the Northern region (0.8-degrees) and the Central region (0.4-degrees) above average. Temperatures dropped in the Southern region to 0.3-degrees above the long-term average in the wake of Cyclone Alfred.

The Bureau of Meteorology forecasts for April, indicate sea surface temperatures will decline overall but remain 0.6-degrees to 1-degree above the long-term April average across the Marine Park.

Rainfall

For the remainder of March, rainfall is likely to be above average for much of Australia. 

Reef health

226 Reef Health Impact Surveys (RHIS) were conducted across the Marine Park. From the 24 reefs surveyed, 17 had some level of bleaching.

In the Central and Southern regions, some reefs showed low levels of coral bleaching. While in the Northern region most reports of bleaching were of low to medium level. While no data was collected in the Far Northern region, this is an area where aerial surveys are being conducted this week.

Crown-of-thorns starfish (COTS) outbreaks continue to be most severe in the Southern Region (Swain Reefs) and between Port Douglas and Lizard Island. Isolated and less severe outbreaks are persisting offshore Townsville and the Whitsundays. The Crown-of-thorns Starfish Control Program is continuing to suppress outbreaks and protect coral across hundreds of reefs.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

Reef Health update | 06 March 2025

We will continue to monitor the cyclone off the Queensland coast and the potential impacts to the Reef. However, at this stage the forecast is predicting that Cyclone Alfred will continue to move south away from the Great Barrier Reef Marine Park.

Cyclone Alfred caused severe wind and wave conditions in the eastern part of the Southern region over the weekend.

Sea surface temperatures remain above average in the Marine Park, however the temperatures are predicted to cool in the coming weeks.

We are continuing to investigate the impacts from the heavy rainfall and flooding event in northern Queensland last month. Satellite imagery has shown extensive flood plumes extending more than 700km along the coastline, spread across inshore, midshelf and outer reefs, seagrass meadows and other marine ecosystems. It’s expected that freshwater has caused damage to some exposed ecosystems.

Targeted aerial surveys are scheduled next week in the Far Northern and Northern regions to assess any Reef health impacts that can be seen from the air.

Temperatures

Sea surface temperatures are slightly above average throughout the Marine Park. In the Northern region temperatures are 0.9-degrees above average, while they have decreased in the Central region to 0.3-degrees above average. Sea surface temperatures remain steady in the Far Northern (0.8-degrees) and Southern (0.4-degrees) regions above average.

The forecasts predict that sea surface temperatures will return to average or near-average temperature later this month.

Rainfall

Rainfall is likely to continue to be above average across much of Northern Australia from March to May.

Reef health

Over the past fortnight, 126 Reef Health Impact Surveys (RHIS) were conducted across the Marine Park. From the 14 sites surveyed, 11 had some level of coral bleaching recorded. In the Central and Southern regions, most reefs showed low levels of coral bleaching — 1 to 10% bleaching prevalence. While in the Northern region some reefs showed medium levels of coral bleaching — 11-30% prevalence.

Targeted aerials surveys will be conducted next week in the Far Northern (North of Cooktown to Cape York) and Northern regions (Cairns to Cooktown) to assess any Reef health impacts that are visible from the air resulting from temperature stress and flooding. 

As of 14 February, Crown-of-thorns starfish (COTS) outbreaks are most severe in the Southern Region (Swain Reefs) and between Port Douglas and Lizard Island. Isolated and less severe outbreaks are persisting offshore Townsville and the Whitsundays. The Crown-of-thorns Starfish Control Program is continuing to suppress outbreaks and protect coral across hundreds of reefs.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

Reef Health update | 27 February 2025

The Great Barrier Reef’s water quality continues to be impacted by the heavy rainfall and flooding across north Queensland earlier this month.

Satellite images show flood plumes continue from flood waters, predominately in the Central region — this may impact the health of coral and seagrass.

We have seen cooling in sea surface temperatures across most of the Reef.  The Central and Southern regions have cooled to near average temperatures. In the Northern and Far North of the Reef sea surface temperatures remain above the long term average.

Tropical Cyclone Alfred has formed in the Coral Sea, we will continue to monitor this system and the potential impacts to the Reef. As this stage the Bureau of Meteorology advice indicates that the Category 2 system will continue on a slow, southward track, well offshore from the Queensland Coast until late this week. 

Temperatures

The forecast for March indicates sea surface temperatures will be slightly reduced from previous forecasts in the Far Northern and Northern regions, but above average in the Central and Southern regions. However, local and regional weather patterns, particularly the presence of Tropical Cyclone Alfred will influence actual sea surface temperatures.

Rainfall

Rainfall is likely to continue to be above average across much of Northern Australia from March to May.

Reef health

Over the past fortnight, 214 Reef Health Impact Surveys (RHIS) were conducted across the Marine Park. From the 19 sites surveyed, 17 had some level of coral bleaching recorded. In the Northern, Central and Southern regions, most surveys showed low levels of coral bleaching — 1 to 10% bleaching prevalence. No data was available for reefs in the Far Northern region.

Despite easing conditions following the low-pressure system earlier this month, river discharge into the Reef lagoon remains high. Satellite images show the flood plumes and resulting algal blooms have extended to the mid-shelf reefs.

As of 14 February, crown-of-thorns starfish (COTS) outbreaks are most severe in the Southern Region (Swain Reefs) and between Port Douglas and Lizard Island. Isolated and less severe outbreaks are persisting offshore Townsville and the Whitsundays. The Crown-of-thorns Starfish Control Program is continuing to suppress outbreaks and protect coral across hundreds of reefs.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

Reef Health update | 19 February 2025

The impacts of the recent heavy rainfall and flooding across north Queensland are continuing to be assessed, including any changes to the Great Barrier Reef’s water quality.

Major to moderate flooding levels have been observed across nearly all river basins covering over 500 kilometres of coast between Cairns and Mackay. Significant flood plumes have been detected entering the Reef lagoon from all affected river systems some of which extend from the inshore to mid-shelf reefs.

The recent low-pressure systems across the Great Barrier Reef in the past weeks did have a cooling effect on sea surface temperatures.

Despite the cooling effect, sea surface temperatures in all regions of the Marine Park remain above historical averages. In the Northern and Central areas of the Marine Park this cooling has been short lived.

Temperatures

Sea surface temperatures have cooled across the Marine Park but continue to exceed historical averages.

The forecast for March indicates sea surface temperatures will remain 0.5–1-degrees Celsius above average across the Reef.

Rainfall

Rainfall is likely to continue to be above average across much of Northern Australia from March to May.

Reef health

Over the past fortnight, 175 Reef Health Impact Surveys (RHIS) were conducted across 19 reefs in the Marine Park. These surveys provide a detailed snapshot of reef health, including a breakdown of habitat and impact assessment.

Reefs surveyed in the Northern, Central and Southern regions showed low levels of coral bleaching—1 to 10% bleaching prevalence. No data was available for reefs in the Far Northern Region.

The Marine Monitoring Program is out sampling sites in the Mackay−Whitsundays, Burdekin, and Wet Tropics areas following the heavy rainfall over the past few weeks. Aerial and satellite imagery is being used to view and assess the flood plume extent, which is expected to move north and east.

Nutrient and sediment-rich, low salinity waters discharging from rivers after heavy rainfall can be detrimental to Reef health, increasing susceptibility to coral disease and bleaching. Prolonged exposure to these waters over the coming weeks could significantly impact the Reef in some locations through reduced light and promotion of algal blooms over large areas.

These stresses can contribute to localised seagrass and coral mortality.

As of last week, crown-of-thorns starfish (COTS) outbreaks were most severe in the Southern Region (Swain Reefs) and between Port Douglas and Lizard Island. Isolated and

less severe outbreaks are persisting offshore Townsville and the Whitsundays. The COTS Control Program is continuing to suppress outbreaks and protect coral across hundreds of reefs.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

The Marine Monitoring Program informs managers and the wider community about the condition of inshore corals and seagrass, and the effects of poor water quality from land-based runoff on these ecosystems.

The program is coordinated by the Reef Authority, with key partners including AIMS, James Cook University—TropWater, the Cape York Water Partnership, and University of Queensland.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

Reef Health update | 12 February 2025

North Queensland continued to be inundated by heavy rainfall over the past week, with many local communities already recording their highest monthly rainfall for February. Rainfall has seen many rivers reach major flood levels.

The increased wind and cloud cover from this low-pressure weather system have cooled temperatures across most of the Marine Park.

The impacts of this weather event on the Marine Park are still being assessed, including any changes to the Reef’s water quality through floodwaters and freshwater intrusions. 

Temperatures

Forecasts indicate sea surface temperatures will remain 0.5-to-1-degree Celsius above average for most of the Marine Park, with higher temperatures expected in the Far Northern region.

Rainfall

Very significant rainfalls have occurred over the catchment over the past week due to the monsoon trough across north Queensland.

Above average rainfall is likely to continue across the north over the next three months.

Reef health

Over the past fortnight, 154 Reef Health Impact Surveys (RHIS) were conducted across 20 reefs in the Marine Park. These surveys provide a detailed snapshot of reef health, including a breakdown of habitat and impact assessment.

Reefs surveyed in the Northern Region, the Cairns–Cooktown area, showed 1–10 per cent bleaching prevalence, while those in other regions were less affected by heat stress. No data was available for reefs above Cooktown in the Far Northern Region. 

The Marine Monitoring Program is out sampling sites in the Mackay−Whitsundays, Burdekin, and Wet Tropics areas following the heavy rainfall over the past few weeks. 

Aerial imagery including recent drone footage collected by the Crown-of-thorns starfish control program is being used to assess flood plume extent.

Crown-of-thorns starfish outbreaks are present in the Southern Region (Swain Reefs) and the Northern ‘initiation zone’ (Port Douglas to Lizard Island), with isolated outbreaks near Townsville and Whitsundays.

The Crown-of-thorns Starfish Control Program is prioritising reducing spawning populations in the "initiation zone" to prevent further spread of this coral-eating species, with concern the increasing population in this area may trigger waves of secondary outbreaks.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

 Reef Health update | 05 February 2025

The heavy rainfall across north Queensland has caused major flooding in some parts, which has severely impacted local communities – our thoughts are with you all.

The severe weather system has generated heavy rainfall, cloud cover and wind, which may provide some cooling benefits across much of the Marine Park. Flooding and resulting freshwater intrusion into the Marine Park may impact seagrass meadows and cause coral bleaching on some inshore coral reefs. This will be monitored using our extended network of partners undertaking standard assessments and reactive surveys.

Temperatures

Heat stress has continued to accumulate across the Reef, with Far North and Northern regions of the Great Barrier Reef exposed to above average sea surface temperatures for longer than the Central and Southern regions. Forecasts indicate sea surface temperatures may reduce over the next week, especially in the Northern and Far Northern regions as a result of the tropical low, however temperatures are still expected to exceed monthly averages by 0.5 to 1 degree Celsius.

Air temperatures have eased in the Great Barrier Reef catchments following the development and movement of the low-pressure system.

Rainfall

Very significant rainfalls have occurred over the catchment due to the slow-moving nature of the tropical low and monsoon trough over north Queensland.

Over the next three months, rainfall is likely to be above average across much of northern and eastern Australia, with the likelihood of above average rainfall exceeding 80% in parts of northern and central Queensland.

Reef health

Sixty-three Reef Health Impact Surveys (RHIS) were conducted across 10 reefs in the Marine Park over the past fortnight. These surveys recorded a low prevalence of coral bleaching, mostly in the Central region.

The Marine Monitoring Program is reviewing its flood response in the Mackay−Whitsundays, Burdekin, and Wet Tropics regions due to the recent heavy rainfall. While road closures are currently impacting access to sampling sites, the team is ready to conduct surveys once it is safe to do so. Satellite imagery will be continually reviewed to measure the extent and exposure of flood plumes entering the Marine Park.

Crown-of-thorns starfish outbreaks are present in the Southern Region (Swain Reefs) and the Northern ‘initiation zone’ (Port Douglas to Lizard Island), with isolated outbreaks near Townsville and the Whitsundays.

The Crown-of-thorns Starfish Control Program is prioritising reducing spawning populations in the "initiation zone" to prevent further spread of this coral-eating species, with concern the increasing population in this area may trigger waves of secondary outbreaks.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

Reef Health update | 29 January 2025

An increase in activity of the monsoon trough across northern Australia is expected to provide a reprieve from hot weather over the coming weeks and could potentially mitigate the impacts of higher sea surface temperatures across the Reef.

Monsoonal conditions bringing wind and rain will potentially reduce elevated sea surface temperatures across the northern and central regions of the Great Barrier Reef Marine Park.

Heat stress is currently highest in the Far North of the Marine Park, progressively declining toward the south, with the Southern region showing the lowest level of accumulated heat stress.

Temperatures

Despite promising forecasts, sea surface temperatures are currently between 1 to 2 degrees Celsius above average, with the highest temperature anomalies recorded in the Northern and Central regions. These higher-than-average temperatures are expected to persist throughout summer, with the peak in March – although local weather conditions across the region will continue to influence outcomes for the Reef during this period.

Air temperatures continue to be above average throughout the Great Barrier Reef catchments but are also expected to ease with the onset of the low-pressure system across the region.

Rainfall

Above average rainfall is expected to continue throughout January. Rainfall is likely to be above average across much of northern and eastern Australia, with the likelihood of above average rainfall exceeding 80% in parts of northern and central Queensland for February through to April.

Reef health

Forty-two reefs were surveyed across the Marine Park over the past fortnight with low prevalence of coral bleaching reported, mainly in the Central and Northern regions.

Crown-of-thorns starfish outbreaks remain the most severe in the Southern Region (Swain Reefs) and the Northern ‘initiation zone’ (Port Douglas to Lizard Island), with isolated outbreaks offshore Townsville and the Whitsundays.

The Crown-of-thorns Starfish Control Program is prioritising reducing spawning populations in the "initiation zone" to prevent further spread of this coral-eating species, with concern the increasing population in this area may trigger waves of secondary outbreaks.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can help by reporting any incidents through the Eye on the Reef app, which is available for download on Google Play or Apple Store.

Reef Health update | 22 January 2025

Heatwave conditions have continued across Queensland over the past week contributing to heat stress on the Reef.

The persistent hot weather means we are seeing heat building up across the Reef, with more heat accumulating in the Far Northern and Northern regions, and less in the Central and Southern regions.

However, it’s important to note that local and regional factors will play a crucial role in determining the health of the Reef. Conditions such as water quality, currents, and local weather patterns, will ultimately influence the Reef’s outcomes this summer.

Temperatures

Air temperatures across the Marine Park have continued to be above average as heatwave conditions persist across most of the catchments.

Sea surface temperatures remain between 1−1.5°C above average across most of the Marine Park, with the highest temperature anomalies recorded in the Northern Region. These higher-than-average temperatures are expected to persist throughout summer, with the peak in March.

Recent data shows 2024 was the third hottest year on record for average sea surface temperatures on the Reef.

Rainfall

Above average rainfall is expected to continue throughout January.

Reef health

Forty-one reefs were surveyed across the Marine Park in the past week with a few isolated cases of coral bleaching — reported, mainly in the Central Region. Limited data were gathered from the Northern Region over this time.

Crown-of-thorns starfish numbers are highest in the Southern Region (Swain Reefs) and the Northern ‘initiation zone’ (Port Douglas to Lizard Island), with isolated outbreaks offshore Townsville and the Whitsundays.

The Crown-of-thorns Starfish Control Program is prioritising reducing spawning populations in the "initiation zone" to prevent further spread of this coral-eating pest species, with concern the increasing population in this area may trigger waves of secondary outbreaks.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience year-round, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

You too can play your part to help protect our iconic Reef. Make sure you know your zones before heading out into the Marine Park and follow safe anchoring practices. Our compliance teams are out in force over the summer so do your bit to protect the Reef, and don’t hook a fine!

Reef Health update | 15 January 2025

Heatwave conditions and above average rainfall have continued across much of the Marine Park over the past week contributing to heat stress on the Reef.

El Niño–Southern Oscillation (ENSO) patterns are consistent with a developing La Niña which is unusual for this time of year.

It’s important to note that local and regional factors will play a crucial role in determining the health of the Reef. Specific conditions in the area, such as water quality, currents, and local weather patterns, will ultimately influence the Reef’s outcomes this summer.

Temperatures

Air temperatures across the Marine Park have been above average as heatwave conditions persist across most of the catchment.

Sea surface temperatures were between 0.8−1.2°C above average across most of the Marine Park, with the highest temperature anomalies recorded in the Northern Region. These are forecast to persist for the rest of the week, with temperature anomalies expected to peak in March.

Rainfall

Rainfall totals ranged from 50 to 100mm across the Marine Park catchment, with isolated areas receiving more than 100mm.

Minor flooding has been reported in some rivers in the Central and Southern region catchments, but there are no reports of flood plumes in the Marine Park.

Above average rainfall is expected to continue throughout January.

Reef health

A few cases of minor coral bleaching have been reported in the Marine Park in the past week, mostly in the Central and Northern regions.

Crown-of-thorns starfish numbers are highest in the Southern Region (Swain Reefs) and the Northern ‘initiation zone’ (Port Douglas to Lizard Island), with isolated outbreaks offshore Townsville and the Whitsundays.

The Crown-of-thorns Starfish Control Program is prioritising reducing spawning populations in the "initiation zone" to prevent further spread of this coral-eating pest species.

Reef management

As the lead managers of the Reef, we are working closely with our partners to monitor conditions across the Marine Park during these high-risk summer months.

We also use a range of management actions to support and build Reef resilience year-round, including enforcing compliance with our zoning plan and ensuring people enjoy the Reef in a responsible way.

Our Marine Park compliance patrols have been out in force over the holiday period, particularly at known illegal fishing hotspots, to ensure Marine Park users are doing the right thing to minimise additional stress to the Great Barrier Reef.

You can do your bit to help protect this World Heritage-listed natural wonder. Make sure you know your zones before heading into the Marine Park and report what you see through the Eye on the Reef App.

Reef Health update | 18 December 2024

The summer has commenced with global sea surface temperatures remaining at near record highs, and forecast models predicting elevated ocean temperatures across the Great Barrier Reef Marine Park over the coming months.

This forecast indicates a risk of exposure to thermal stress building across the Reef during summer, and we are starting to see it now.

The National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch has the Central and Northern regions of the Marine Park on a “bleaching warning” with accumulated heat stress of 1 degree heating week, which means coral bleaching is possible, particular for sensitive coral species.

From December to March, there is a high chance of unusually high rainfall for catchments adjacent to the Reef, particularly Cape York Peninsula, with above average falls predicted for all other Marine Park catchment areas.

It’s important to note that local and regional factors will play a crucial role in determining the health of the Reef. The specific conditions in the area, such as water quality, currents, and local weather patterns, will ultimately influence the Reef’s outcomes this summer.

Temperatures

Sea surface temperatures remain high across the Marine Park, with most areas currently 1-1.5°C above the average for December.  

Rainfall

Over the past few weeks, rainfall in the Peninsula, North Tropical Coast, and Tablelands (west of Cairns) districts exceeded 200 mm. However, the Bureau has reported no significant river flooding freshwater intrusion, or sediment runoff into Reef waters.

Reef health

From mid-November to December 12, 2024, 739 Reef Health Impact Surveys (RHIS) were conducted across 79 reefs in the Marine Park. These surveys, carried out by trained and experienced managers and researchers, are designed to quickly assess the condition of the reefs.

Low levels of coral bleaching were observed on some of the surveyed reefs, mainly in the Central and Northern regions of the Marine Park. Sea surface temperatures are currently high enough to cause heat stress to corals, increasing the risk of coral bleaching during this time of year.

Crown-of-thorns starfish populations continue at outbreak densities at the Swain Reefs in the Marine Park’s Southern Region, as well as on offshore reefs between Port Douglas and Lizard Island. Isolated outbreaks also persist on several reefs offshore Townsville and the Whitsunday Islands in the Central Region.

The outbreak of this starfish between Port Douglas and Lizard Island, an area known as the ‘initiation zone’, is concerning for its potential to ‘seed’ secondary outbreaks on downstream reefs further south.

Late December is the starfish’s breeding season. The control program’s focus during this time is reducing its population in this initiation zone to reduce the risk to reefs further south. 

Reef management

Reef protection continues to be a year-round activity, but our focus is heightened over summer when the Reef is more at risk from cumulative impacts including elevated sea surface temperatures, cyclones and freshwater inundating the marine environment.

We are working closely with our partners to protect and strengthen the resilience of the Reef through a range of management actions, including controlling coral-eating crown-of-thorns starfish and our year-round compliance campaign to deter illegal fishing.

If you are out in the Marine Park, you can report what you see through the Eye on the Reef app and help do your bit in protecting this World Heritage-listed natural wonder by knowing the zoning rules.
 

Reef Health update | 11 December 2024

The Reef Authority continues to monitor conditions on the Reef and work with its science, Traditional Owner and management partners to prepare for the 2024–25 summer.

The summer has commenced with global sea surface temperatures remaining at near record highs, and forecast models predicting elevated ocean temperatures across the Great Barrier Reef Marine Park over the coming months.

This forecast indicates a risk of thermal stress building across the Reef during summer.

From December to March, there is a high chance of unusually high rainfall for parts of the Reef, particularly the Cape York peninsula, with above average predictions for all other Marine Park catchment areas.
Air temperatures are also expected to be warmer than average throughout January to March.

Overall, the Bureau of Meteorology forecasts a wet and warm December, and then drier and warm conditions over the Great Barrier Reef for January. An average number of cyclones is forecasted  typically four across the region. However, these cyclones are likely to be more intense due to warmer-than-average sea temperatures. 

November and early December conditions

Temperatures

Sea surface temperatures throughout the Northern and Central regions were about 0.5°C above average during November, and up to 0.8°C above average in the Southern Region. Currently, sea surface temperatures are 0.5°C above average for most of the Reef, but up to 1°C above average in the Far Northern and Southern regions.  

Rainfall

November saw lower than average rainfall for most Reef catchments. December is expected to bring higher than average rainfall particularly in the Northern regions.

Reef health

During November 559 Reef Health Impact Surveys  were conducted across 72 reefs in the Marine Park, recording a low incidence of coral bleaching and coral disease mainly from the Central Region, between Townsville and the Whitsundays. These comprehensive surveys, conducted by trained and experienced managers and researchers, are designed to enable rapid assessment of reef condition.

Crown-of-thorns starfish populations continue at outbreak densities at the Swains Reef in the Marine Park’s Southern Region, as well as on offshore reefs between Port Douglas and Lizard Island. Isolated outbreaks also persist on several reefs offshore Townsville and Whitsunday in the Central Region. 
The outbreak of this starfish between Port Douglas and Lizard Island, an area known as the ‘initiation zone’, is concerning for its potential to ‘seed’ secondary outbreaks on downstream reefs further south. 

In the lead up to the starfish’s breeding season, typically late December at the start of the tropical wet season, the control program’s focus is reducing its population in this initiation zone to suppress the buildup of the primary outbreak.

Reef management

Last week our annual summer workshop was held with management partners, Traditional Owners, scientists, tourism, and Reef-dependent industry representatives. Workshop participants focused on current conditions and the latest environmental forecast modelling to understand the likely outlook for summer, and to plan a coordinated approach for the months ahead.

It is too early to tell exactly what summer will bring, and local and regional conditions will ultimately influence Reef health outcomes.

Reef protection continues to be a year-round activity. We are working with our partners to protect and strengthen the resilience of the Reef through a range of management actions, including controlling coral-eating crown-of-thorns starfish and our year-round compliance campaign to deter illegal fishing.

If you are out in the Marine Park, you can report what you see through the Eye on the Reef app, and make sure you know your zones to help do your bit in protecting this World Heritage-listed natural wonder.
 

Reef Health update | November 2024

The Bureau of Meteorology is predicting a warm 2024–25 summer season as a result ongoing high sea surface temperatures. 

The Bureau, together with CSIRO, recently released the latest State of the Climate 2024 report, which looks at long-term climate trends in Australia. 

• The report found:
• Sea surface temperatures, ocean heat content, and acidification in the Marine Park have all been rising in recent decades.
• Since 1900, sea surface temperatures have increased by 1.08°C, contributing to more frequent extreme heat events, both on land and in the ocean.
• The world's oceans have absorbed over 90 per cent of the extra energy from greenhouse gases. 

The report highlights the importance of the work we do to build the resilience on the Great Barrier Reef, including programs such as the Crown-of-thorns starfish Control Program which is doing critical work to reduce outbreaks of the starfish to protect coral cover. 

On a positive note, it’s coral spawning season — a time of regeneration for the Reef, as spawning corals pass on heat-tolerant genes, helping the Reef adapt to warmer waters.

October conditions

During October, sea surface temperatures were about 0.5°C above average across the Marine Park.

Rainfall was slightly below average across Queensland, with low chances of extreme rain in November.

A total of 497 Reef Health Impact Surveys were conducted across 41 reefs in the Marine Park, showing minor coral bleaching in some areas, likely linked to earlier mass bleaching this year. Coral recovery and mortality remains varied across the Reef.

There were no reports of disease or physical damage (such as that caused by anchors) during these surveys. 

Crown-of-thorns starfish outbreaks continue to be an issue at some reefs, particularly in areas like Swain Reefs and offshore Port Douglas, and isolated outbreaks are ongoing on several reefs offshore Townsville and the Whitsundays.

During coral spawning, the focus of the Crown-of-thorns starfish control program is to reduce starfish populations to protect the Reef's recovery.

Reef management

With summer approaching, the Reef is more vulnerable to extreme weather like cyclones and heatwaves. 

We’re working closely with partners including the Queensland Parks and Wildlife Service through the Reef Joint Field Management Program, as well as the tourism industry and scientific organisations such as the Australian Institute of Marine Science to monitor the Reef 24/7.

Over the past month, we've been working with the tourism industry, running Eye on the Reef training which teaches operators how to gather important data on Reef health, which we use year-round to monitor conditions.

The training will continue this month, including training a new cohort of Master Reef Guides. 

Our year-round management actions are geared towards building and supporting Reef resilience, including enforcing compliance with the Reef’s zoning plan and ensuring people are enjoying the Reef in a responsible way.

Stay up-to-date with what’s happening across the Reef by following our social channels and downloading the Eye of the reef app to let us know what you see in the Marine Park.

Reef Health update | October 2024

Global sea-surface temperatures remain above average across most of the planet.

Sea-surface temperatures across the Great Barrier Reef Marine Park are around 0.6°C higher than average for this time of year but these temperatures are not at levels that typically cause impacts such as coral bleaching.

Sea-surface temperatures across the Marine Park are expected to remain from 0.4 to 1.2°C above average from October to December. However, local weather conditions will have a key influence on sea surface temperatures during the summer.

The El Niño–Southern Oscillation weather pattern’s neutral condition remains, and the Bureau of Metrology predicts these neutral conditions to continue over the summer.

Reef Health summary for September  

This Reef Health update is based on data collected during September, 2024.

In September, 348 Reef Health Impact Surveys (RHIS) were conducted across 31 reefs in the Marine Park.

Reef Health Impact Surveys are a quantifiable survey method used mostly by the Reef Authority, Queensland Parks and Wildlife Service and researchers as well as trained tourism operators.

Most reefs surveyed showed no signs of coral bleaching, with very few cases of minor bleaching reported in each region. Any coral bleaching observed is not likely related to current sea-surface temperatures as they are under the levels that would usually cause coral bleaching. The surveys also found minor damage (for example, from anchor damage) on some corals but no signs of disease in all regions of the Marine Park.

There was average or below average rainfall reported across all Reef catchments in September.

The highest known crown-of-thorns starfish outbreak densities continue at some reefs in the offshore Southern Region (Swain Reefs) and isolated outbreaks remain on several reefs offshore Townsville and Whitsunday in the Central Region.

The Crown-of-thorns starfish Control Program is in operation, helping us to target those veracious coral predators so we can support the recovery of coral ecosystems and their resilience into the future.

Reef management

The Reef Authority collaborates with science and management institutions to maintain a contemporary understanding of Reef health and the impacts of climate change on the World Heritage Area.

The Australian Institute of Marine Science, the Bureau of Meteorology, CSIRO, and other research institutions continue to deliver monitoring and research that documents the long-term trend of Reef conditions and climate patterns. This includes multiple monitoring programs under the Reef 2050 Integrated Monitoring and Reporting Program.

During the summer months, the Reef is more vulnerable to extreme weather events including cyclones, marine heatwaves and flooding – the effects of which are compounded by climate change.

As we move into the warmer months, there is a lot of work being done with our partners to prepare for summer.

We are also preparing for the upcoming coral spawning, which only occurs a few nights of the year. During this phenomenal event, millions of bundles of coral sperm and eggs are released into the ocean allowing for mass reproduction—a positive sign for Reef renewal and regeneration.

You can do your bit to help protect the Reef by following a few simple steps:

• Use public moorings where available and do not anchor within no-anchoring areas – they are there to protect the coral.
• Where possible, anchor in sand or mud away from corals and other fragile marine environments. Suitable areas often show up as flat and smooth on your sounder.
• Never wrap anchor rope or chain around bommies or large coral heads.
• If anchoring overnight, anchor before nightfall and double-check the swing room.
• Use your sand anchor and reef pick appropriately to minimise damage.
• Motor towards the anchor when hauling it in and retrieve the anchor when the line is vertical.
• If the anchor is caught on a reef, free it by hand wherever possible.
• Do not force the anchor free by motoring forward.
• Keep watch to make sure the anchor isn’t dragging.