A serious marine heatwave caused the fifth mass coral bleaching event since 2016. Intense rain from Cyclone Jasper washed huge volumes of freshwater and sediment onto corals closer to shore, and Cyclone Kirrily crossed the central region. Some parts of the southern reef endured heat stress at levels higher than previously measured.
This year’s marine heatwaves peaked in February and March, when researchers from AIMS and the Great Barrier Reef Marine Park Authority conducted additional surveys from the air and underwater.
What this showed was the 2024 mass bleaching event was one of the most serious and widespread so far. It took place against the fourth recorded global bleaching event.
Heat stress is cumulative – it gets worse the longer corals have to endure warmer water.
https://theconversation.com/high-coral-cover-amid-intense-heatwaves-and-bleaching-heres-how-both-can-be-true-on-the-great-barrier-reef-235510
the cover reported on your chart is accurate. but the explanation reveals the relative condition of the reef.
Our surveys found average hard coral cover in the year to June 2024 was:
- 39.5% in the northern region (north of Cooktown), up from 35.8% last year
- 34% in the central region (Cooktown to Proserpine), up from 30.7%
- 39.1% in the southern region (south of Proserpine), up from 34%.
This year’s coral cover averages are higher than the last few years, but not by much. Statistically speaking, they’re within the margin of error.
By contrast, the reef recovered much more strongly during the less stressful years from 2018 to 2022. In the northern region, coral cover increased by 22.9%.
If we were living in ordinary times, corals would grow back over a decade or two, giving rise to more diverse reefs.
But as the world heats up, the reprieve from heatwaves and extreme weather is getting shorter and shorter. In recent decades, both size and frequency of events causing severe damage to the reef have increased.
Aus Inst of Marine Science LINK
