A new survey, published by the Australian Institute of Marine Science, has found continued coral recovery across two-thirds of the Great Barrier Reef in Australia, largely due to increases in the fast-growing Acropora corals.
The highest amounts of coral cover were found in the northern and central parts of the reef, while coral cover in southern parts decreased. Since monitoring began 36 years ago, the Australian Institute of Marine Science has conducted annual surveys of the UNESCO World Heritage Site by using aerial surveys and divers.
The survey comes after a mass bleaching event was confirmed in March, the fourth in six years. Australian Institute of Marine Science’s chief executive Paul Hardisty said: “In our 36 years of monitoring the condition of the Great Barrier Reef we have not seen bleaching events so close together.”
While the latest results show that the Great Barrier Reef is able to recover, climate change is exacerbating cyclones, bleaching events and other damaging events, making them last longer and more frequent. The study also points out that coral-eating crown-of-thorns starfish outbreaks, while generally decreasing on the survey reefs, is still a problem in some parts of the southern reef. Scientists believe that the species’ survival rate improves when sea temperatures rise, making them an even bigger problem for corals. One publication even suggests that up to 50% of coral loss on the Great Barrier Reef can be attributed to the crown-of-thorns.
As the survey sums it up: “The combination of few acute stresses and lower accumulated heat stress in 2020 and 2022 compared to 2016 and 2017 has resulted in low coral mortality and has allowed coral cover to continue to increase in the Northern and Central GBR.”
According to officials, however, the new Acropora coral growth is particularly vulnerable to future climate change and other threats and could quickly disappear if swift action to protect the reef and mitigate climate change further isn’t taken in the near future.
The survey reads: “In periods free from intense acute disturbances, most GBR coral reefs demonstrate resilience through the ability to begin recovery. However, the reefs of the GBR continue to be exposed to cumulative stressors. The prognosis for the future disturbance regime suggests increasing and longer-lasting marine heatwaves, as well as the ongoing risk of outbreaks of crown-of-thorns starfish and tropical cyclones. Therefore, while the observed recovery offers good news for the overall state of the GBR, there is increasing concern for its ability to maintain this state.”
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Photography courtesy of Ocean Image Bank: Mark Fitz, Matt Curnock, and The Ocean Agency.