Reef health update | 9 April 2026

Sea surface temperatures continued to cool this week, dropping by 0.2–0.4°C across most of the Marine Park.

Tropical Cyclone Maila (37U) has now formed in the Solomon Sea and has rapidly intensified into a Category 5 system. Current Bureau of Meteorology forecasts show the system tracking into the Coral Sea, with a likely coastal crossing near Cape York Peninsula this weekend or early next week. Maila is expected to bring localised heavy rainfall, increasing the risk of flood plumes in the Marine Park and possible damage to coral and seagrass habitats from strong waves.

Encouragingly, coral bleaching alert levels have eased. The USA’s National Oceanic and Atmospheric Administration (NOAA), which monitors ocean temperatures globally, has downgraded the Northern, Central, and Southern regions to no stress conditions, following further drops in sea surface temperatures - reflecting heat stress easing across the Marine Park.

Temperature

Despite recent decreases in sea surface temperatures, they remain around 0.6–0.7°C above the long-term April average. The Far Northern and Northern regions are still experiencing the effects of accumulated marine heatwave exposure from earlier in summer, which may cause bleaching in some coral species.

Rainfall

Weekly rainfall across most catchments was average or below average, with totals generally under 100mm except for the Wet Tropics region receiving up to 150mm.

Rainfall in March was higher than usual across most Marine Park catchments, with the Cape York, Fitzroy and Burnett–Mary catchments having some of the highest March rainfalls recorded.

Reef health

Over the past week, 19 Reef Health Impact Surveys were completed across five reefs in the Marine Park.

In the Northern region, four reefs were surveyed with high (31–60%) to very high (61–90%) coral bleaching recorded on three reefs. These bleaching patterns in the Northern region are likely linked to heat stress accumulated over the summer combined with earlier flood plume impacts. All four reefs surveyed in the Northern region also showed severe coral damage, likely caused by storm impacts associated with Ex-Tropical Cyclone Narelle.

Limited surveys in the Far Northern region mean the full extent of coral bleaching is still emerging, but higher levels are expected given its prolonged exposure to above-average sea surface temperatures.

In the Central region, one reef was surveyed and no bleaching was recorded.

Additional Eye on the Reef observations from across the Marine Park reported bleaching on 11 of 19 reefs. No coral disease was recorded during the period.

Crown-of-thorns starfish control

As of 31 March 2026, the Crown-of-Thorns Starfish Control Program and Reef Joint Field Management Program response teams have surveyed and, where needed, culled starfish on 187 reefs this financial year.

Of these reefs:

Crown-of-thorns starfish are at sustainable levels on 80 reefs (43%).

Active culling is underway on 60 reefs (32%) to suppress outbreaks.

Starfish have been detected on 47 reefs (25%), and these reefs will be targeted for culling based on priority and actioned when operationally feasible.

The program uses a science-based prioritisation process to focus effort on reefs with high ecological and economic value, with the aim of maximising coral protection.

Sea surface temperatures continue to ease across the Marine Park this week, dropping by around 0.1–0.2°C.

Heavy rainfall from ex-Tropical Cyclone Narelle caused a major flood in the Far Northern region, with the Pascoe River reaching 19.3 metres - the highest level recorded in more than 50 years and likely a one-in-200-year event. The flood plume may affect nearby ecosystems like seagrass meadows and inshore reefs by lowering salinity and increasing exposure to sediments, nutrients, and pesticides.

The Bureau of Meteorology forecasts a tropical low (37U) may form near the Solomon Islands by Thursday, with a moderate to high chance of developing into a cyclone over the weekend. At this stage, it is expected to stay away from the Queensland coast over the next week.

Temperature

Despite recent decreases in sea surface temperatures, they remain around 0.7°C above the long-term monthly average. The Far Northern and Northern regions are still experiencing the effects of accumulated marine heatwave exposure from earlier in summer, which may cause bleaching in some corals species.

Rainfall

Weekly rainfall totals were mostly average or below average across the Marine Park catchment areas during the past week, with up to 100mm of rain recorded over the reporting period.

Reef health

Over the past week, 43 Reef Health Impact Surveys were conducted across seven reefs in the Marine Park. In the Northern region, five reefs were surveyed with coral bleaching ranging from low (1–10%) to very high (61–90%). In the Central region, two reefs were surveyed and no coral bleaching was observed.

Limited surveys in the Far Northern region mean the full extent of coral bleaching is still emerging, but higher levels are expected given its prolonged exposure to above-average sea surface temperatures.

Additional Eye on the Reef observations from across the Marine Park reported bleaching on 9 out of 24 reefs.

High levels of bleaching in the Northern region may be linked to prolonged heat exposure and impacts from flood plumes. Surveys also recorded moderate to extreme coral damage on three Northern reefs, likely from storm impacts related to Ex-Tropical Cyclone Narelle. One Central reef showed low damage from storms activity, and one reef had moderate coral disease.

Crown-of-thorns starfish control

The Crown-of-thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

We are thinking of communities in the Far Northern region affected by Tropical Cyclone Narelle.

Tropical Cyclone Narelle passed through the Far Northern region of the Marine Park as a Category 5 system and crossed the Queensland coast as a Category 4 on 20 March. The cyclone generated intense winds and strong wave action along its track in the Far Northern Region, with modelling also indicating wide-spread high wave action in the Northern region, particularly across offshore reefs. The extent of damage will be assessed in the coming weeks.

The El Niño–Southern Oscillation (ENSO) climate pattern, La Niña, continues to weaken, and conditions are expected to return to a neutral phase in early autumn. However, forecasts suggest that by winter, the system may shift into an El Niño phase, which often brings warmer and drier conditions to much of Australia.

Temperature

Sea surface temperatures continue to fall across the Marine Park, with the largest drop (0.8°C) recorded in the Northern region, however they remain around 0.6°C above the long-term monthly averages.

Despite recent decreases in sea surface temperatures, some reefs in the Far Northern and Northern regions have accumulated heat stress exposure that can cause some coral species to bleach.

Rainfall

From 16–22 March, localised heavy rainfall was recorded in the Cape York and Wet Tropics catchments as Tropical Cyclone Narelle moved through the region. Weekly rainfall totals ranged from 200–450mm, with some locations receiving more than 100–200mm in a single day.

Flood warnings are active across parts of the Cape York catchment, and significant flooding has been reported in the Pascoe River, which is currently at record levels.

Reef health

Over the past week, 67 Reef Health Impact Surveys were completed across nine reefs in the Northern (between Innisfail and just above Cooktown), Central (between Mackay and Innisfail) and Southern regions (between Bundaberg and Mackay).

Coral bleaching in the Northern region varied from moderate (11–30%) to very high (61–90%). Of the five reefs surveyed, one reef also showed signs of coral mortality. These impacts are likely linked to a combination of exposure to ongoing heat stress and recent floodwaters.

In the Central region one reef was surveyed, with no bleaching recorded.

In the Southern region 3 reefs recorded medium (11–30%) coral bleaching prevalence.

Additional Eye on the Reef observations from across the Marine Park reported bleaching on 9 of 20 surveyed reefs. Coral damage was recorded on 6 reefs, and coral disease was observed on 3 reefs.

Crown-of-thorns Starfish Control

The Crown-of-thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

Tropical Cyclone Narelle (currently Category 5) has developed in the Coral Sea and is forecast to decrease to a Category 4 before crossing the Far Northern region of the Marine Park and making landfall on Friday. The system is expected to bring strong wind and wave action and heavy rainfall, which are likely to damage some reefs and increase the likelihood of freshwater runoff into the Marine Park.

Sea surface temperatures have eased slightly over the past week, particularly in the Northern region (between Innisfail and just above Cooktown), while remaining relatively stable elsewhere.

Encouragingly, coral bleaching alert levels have eased in recent days. The USA’s National Oceanic and Atmospheric Administration (NOAA), which monitors ocean temperatures globally, has downgraded the Far Northern and Northern regions to bleaching watch status following a drop in sea surface temperatures. Most other areas of the Marine Park are expected to return to no heat stress conditions.

Temperature

Temperatures are still slightly above the long-term monthly average for March across the Marine Park. The Far Northern (between Cape York and north of Cooktown) region is around 0.6°C above average, the Northern region (between Innisfail and just above Cooktown) around 1.1°C above average, and the Central (between Mackay and Innisfail) and Southern (between Bundaberg and Mackay) regions are around 1°C above average.

Despite recent decreases in sea surface temperatures, some reefs in the Far Northern and Northern regions have accumulated exposure to heat stress that can cause some coral species to bleach.

The most likely outlook from NOAA’s four-month forecast suggests heat stress will remain low to moderate across the Marine Park into winter.

Rainfall

From 9–15 March, heavy rainfall occurred in parts of the Burnett–Mary, Wet Tropics and Fitzroy catchments.

Weekly totals ranged from 300–400mm in some areas, with several locations receiving more than 200mm in a single day. Rainfall in the Burnett–Mary catchment is among the highest on record for this time of year.

Flooding has been reported in the Burnett River, and flood warnings remain in place across affected catchments. These conditions may lead to freshwater runoff into the Marine Park, which will continue to be monitored.

Reef health

Over the past week, 139 Reef Health Impact Surveys were completed across 19 reefs in the Far Northern, Northern and Central regions. In the Far Northern region, most surveyed reefs showed no to low coral bleaching, with a small number recording low to medium levels (1–30%), and no fully bleached coral or mortality observed.

Coral bleaching in the Northern region varied, from moderate to very high (11–90%). Of the six reefs surveyed, four showed moderate to very high levels of coral bleaching. On these reefs, some corals were fully bleached, and two reefs also recorded small areas of coral mortality. These impacts are likely linked to a combination of exposure to recent heat stress and floodwaters.

In the Central region, one reef recorded low levels of bleaching, with no fully bleached coral or mortality. Additional observations from Eye on the Reef monitoring programs reported coral bleaching on 9 of the 22 reefs surveyed. Coral damage was recorded on 12 reefs and coral disease on seven reefs.

Crown-of-thorns starfish control

The Crown-of-thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

Reef health update - 12 March 2026

Sea surface temperatures eased slightly across the Marine Park over the past week.

A tropical low crossed the Marine Park on 5–6 March. The system, together with a monsoon trough, brought heavy rainfall to the Cape York, Wet Tropics and Mackay–Whitsunday catchments. While this has helped keep temperatures down across the Reef, it also increases the likelihood of freshwater runoff entering the Marine Park.

Another tropical low (34U) is forecast to develop in the Coral Sea off the East Coast of North Queensland. Forecasts continue to be monitored for any potential impacts to the Reef.

Temperature

Over the past week sea surface temperatures dropped from around 30°C to 29.1°C in the Far Northern region following recent weather systems. Sea surface temperatures in other regions also declined slightly, by around 0.1–0.4°C.

Despite this, sea surface temperatures remain above the long-term average. The Far Northern, Central and Southern regions are currently around 0.7–0.9°C above average, while the Northern region remains around 1.3°C above average.

As a result, heat stress continues to build across parts of the Marine Park. Some reefs in the Far Northern and Northern regions are experiencing conditions that may lead to bleaching in heat-sensitive corals.

Rainfall

From 2–8 March, heavy rainfall fell across the Cape York, Wet Tropics and Mackay–Whitsunday catchments. Weekly totals reached 300–400mm in some areas, with several locations receiving more than 200mm in a single day. Overall, rainfall for March so far is above to well above average in these regions.

Heavy rainfall can increase the risk of freshwater runoff entering the Marine Park.

Reef health

Over the past week, 73 Reef Health Impact Surveys were completed across nine reefs in the Northern and Central regions.

Monitoring shows that coral bleaching impacts remain varied across the reefs surveyed.

Surveys on reefs in the Northern region recorded coral bleaching ranging from low levels (1–10%) to very high levels (61–90%). One reef in the Central region recorded medium bleaching levels (11–30%).

Two reefs in the Northern region recorded small areas of fully bleached coral (less than 5%) and low levels of recent coral mortality (less than 3%).

Coral damage was recorded on five reefs and coral disease was observed on four reefs.

Additional observations from the Eye on the Reef monitoring programs also reported coral bleaching on eight of the 13 reefs surveyed.

In the coming weeks, Reef Authority and Queensland Parks and Wildlife Service teams will carry out additional surveys in areas that have experienced high heat exposure to better understand impacts on reef health.

Crown-of-thorns starfish control

The Crown-of-thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

Our response and ongoing work

Marine Monitoring Program teams and partners were also in the field sampling flood waters from the Annan and Endeavour rivers, with further sampling planned for the Normanby River in the coming week.

The Reef Authority’s management decisions are informed by data collected by our teams on the water, including the Reef Joint Field Management Program and Crown-of-thorns Starfish Control Program as well as the collaborative efforts of researchers, tourism operators, contractors and partners.

Management actions remain focused on supporting Reef resilience, including enforcing compliance with zoning rules and encouraging responsible use of the Marine Park.

#reefhealth #lovethereef #greatbarrierreef

A tropical low is developing in the Coral Sea off the east coast of North Queensland. The Bureau of Meteorology advises there is currently a low to moderate chance of it developing into a tropical cyclone. Increased wave action from this system may affect some shallow reef habitats.

Monsoonal activity and the tropical low are expected to bring heavy rainfall to most Marine Park catchments. This increases the risk of flooding and freshwater runoff into the Marine Park.

SeaWeek 2026 is being celebrated from 28 February to 8 March, with this year’s theme “Caring for Planet Water”. The week highlights the importance of ocean literacy and the role healthy oceans play in regulating climate, supporting biodiversity and sustaining communities. It’s a timely reminder of the connection between weather, water quality and Reef health, and the shared responsibility to care for our marine environment.

Temperature

Heat stress continues to build across parts of the Marine Park. Some reefs in the far northern and northern regions are experiencing conditions that may lead to bleaching in heat-sensitive corals.

Over the past week, sea surface temperatures in the far northern region increased from 29.5°C to 30°C and are now about 1.5°C above the long-term monthly average. Sea surface temperatures in the north regions are also about 1.5°C above the long-term monthly average while those in the Central and Southern regions remained relatively stable at 0.8°C to 1°C above average.

Rainfall

Rainfall was average across most Marine Park catchments over the past week. However, monsoonal activity and the tropical low are expected to bring heavier rainfall in the coming week.

Reef health

Over the past week, 91 Reef Health Impact Surveys were completed across six reefs in the northern and central regions.

Low levels of coral bleaching (1–10%) were recorded on four northern reefs and one central reef. One northern reef also recorded low levels of physical damage (e.g. from anchors). No disease was recorded in surveys.

Eye on the Reef monitoring programs also reported coral bleaching on 12 of the 28 reefs surveyed. No surveyed reefs showed fully bleached or recently dead coral colonies.

Crown-of-thorns starfish control

As of 28 February 2026, the Crown-of-Thorns Starfish Control Program and Reef Joint Field Management Program response teams have surveyed and, where needed, culled starfish on 157 reefs this financial year.

Of these reefs:

• Crown-of-thorns starfish are at sustainable levels on 61 reefs (39%).
• Active culling is underway on 57 reefs (36%) to suppress outbreaks.
• Starfish have been detected on 39 reefs (25%), and these reefs will be targeted for culling based on priority and actioned when operationally feasible.

The program uses a science-based prioritisation process to focus effort on reefs with high ecological and economic value, with the aim of maximising coral protection.

Our response and ongoing work

Management actions remain focused on supporting Reef resilience, including enforcing compliance with zoning rules and encouraging responsible use of the Marine Park.

The Reef Authority continues to work closely with the Reef Joint Field Management Program, the Crown-of-Thorns Starfish Control Program, researchers, tourism operators, contractors and partners to ensure management actions are guided by the latest data from across the World Heritage Area.

Reef health update | 26 February 2026

Over the past week, sea surface temperatures across the Marine Park have remained relatively stable.

However now that we are well into summer, there is heat build-up in the system, particularly in the Far Northern and Northern regions of the Marine Park.

The USA’s National Oceanic and Atmospheric Administration (NOAA), which monitors ocean temperatures globally, has updated the coral bleaching alert levels across parts of the Marine Park, meaning the risk of coral bleaching has increased with the Far Northern region at alert level 2 and the Northern region at alert level 1. The Central region remains at warning status and Reef health monitoring is ongoing across all regions.

The Bureau of Meteorology forecasts scattered rainfall across Marine Park catchments over the coming week, with temperatures expected to remain close to monthly averages.

Temperature

Sea surface temperatures are currently around 0.7°C above average in the Southern region and between 0.8°C and 1.2°C above average in the Central, Northern and Far Northern regions.

Forecasts for March indicate that temperatures in the Far Northern region are likely to remain elevated, reaching up to 1.2°C above average, while other regions are expected to stay between 0 and 0.8°C above the long-term average.

Rainfall

From 16 to 22 February, localised heavy rainfall occurred in the Mackay–Whitsunday catchment, with weekly totals between 150 and 500mm and some daily totals exceeding 200mm.

Heavy rainfall can lead to freshwater runoff into the Marine Park, and subsequent lower salinity in Reef waters. This runoff may also carry sediments, nutrients and pesticides, placing additional stress on nearby marine ecosystems.

Reef health

Over the past week, 70 Reef Health Impact Surveys were completed across 11 reefs in the Northern, Central and Southern regions of the Marine Park, with most surveys conducted in the Northern region.

Low to high levels of coral bleaching (1–60%) were recorded on five reefs in the Northern region, and medium levels (11–30%) were recorded on one reef in the Southern region. Low level damage was reported on 23 reefs and disease on 21 reefs, mostly in the Northern region.

Additional observations from Eye on the Reef monitoring programs also reported coral bleaching on 21 of the 38 reefs surveyed. No surveyed reefs showed fully bleached or recently dead coral.

Crown-of-thorns starfish control

The Crown-of-thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

Our response and ongoing work

Crown-of-thorns starfish (COTS) outbreaks continue across the Marine Park and specialised dive teams are working across targeted reefs to survey and cull these predatory starfish.

Management actions remain focused on supporting Reef resilience, including enforcing compliance with zoning rules and encouraging responsible use of the Marine Park.

The Reef Authority continues to work closely with the Reef Joint Field Management Program, the Crown-of-Thorns Starfish Control Program, researchers, tourism operators, contractors and partners to ensure management actions are guided by the latest data across the World Heritage Area.

Reef health update – 12 February 2026

Summary

Sea surface temperatures have increased slightly across the Far North, North and Central regions over the past week, with little change in the southern region. Temperatures are tracking slightly above the long-term average with the Northern region (Cooktown – Innisfail) experiencing above-average conditions.

The Bureau of Meteorology has forecast a tropical low (23U) to form in the Coral Sea. There is a low chance (5–10%) it will develop into a tropical cyclone by the weekend. The system is expected to remain offshore and may bring localised rainfall to Marine Park catchments in the coming week.

The breeding season continues across the Reef, with turtle hatchlings emerging from nests and making their way to the sea from late January through April, especially at dawn and dusk. Seabirds are also nesting and feeding across island and reef habitats, and many fish species are spawning and laying eggs during the warm summer months, taking advantage of the productive wet season conditions.

Temperature

Sea surface temperatures are currently around 0.4–0.5°C above the long-term average in the Far Northern, Central and Southern regions. The Northern region is averaging around 1°C above the long-term monthly average.

While there has been some accumulation of heat stress, particularly in northern Reef waters, this remains below the level where we would expect to see significant coral bleaching impacts.

Rainfall

From 2–8 February, rainfall was lower than expected in the Marine Park catchments, with average rainfall occurring in the Wet Tropics and Mackay–Whitsundays. Heavy rainfall is currently forecast in areas which may be affected by the Tropical Low 23U.

Reef health

America’s National Oceanic and Atmospheric Administration’s (NOAA) coral bleaching alert level for the Northern region has moved from bleaching watch to bleaching warning, meaning coral bleaching is possible, following the recent temperature increases. Monitoring is ongoing across the Marine Park.

During the past week, 86 Reef Health Impact Surveys were completed across 10 reefs in the Northern, Central and Southern regions.

Low to medium levels of coral bleaching (1–30%) were recorded on four reefs in the Northern region and one reef in the central region. Most surveyed reefs showed no to low levels of bleaching.

Additional observations from Eye on the Reef monitoring programs reported coral bleaching on 11 of the 26 reefs surveyed. Impacts remain localised and are being closely monitored.

Crown-of-thorns starfish control

The Crown-of-Thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

Our response and ongoing work

Marine Monitoring Program teams and partners are sampling water quality and tracking flood plumes in the Burdekin. On Magnetic Island, training is underway to support local citizen scientists to help monitor water quality.

Crown-of-thorns starfish (COTS) outbreaks continue across the Marine Park and specialised dive teams are working across targeted reefs to survey and cull these predatory starfish.

Management efforts remain focused on supporting Reef resilience, including enforcing zoning rules, encouraging responsible use of the Marine Park and responding early to emerging risks.

The Reef Authority continues to work closely with the Reef Joint Field Management Program, the Crown-of-Thorns Starfish Control Program, researchers, tourism operators, contractors and partners to ensure decisions are guided by up-to-date information.

For more information, visit - www.gbrmpa.gov.au/learn/reef-health/reef-health-updates