- According to the Australian Institute of Marine Science’s (AIMS) annual long-term monitoring report, Australia’s northern and central Great Barrier Reef (GBR) has experienced high levels of coral reef cover over the past 36 years.
- The researchers also warned that the gains could be quickly reversed due to rising global temperatures.
Key highlights of Report
- It states that reef systems are resilient and capable of recovering after disturbances such as accumulated heat stress, cyclones, predatory attacks.
- It shows record levels of region-wide coral cover in the northern and central GBR since the first ever Australian Institute of Marine Science (AIMS) survey was done.
- Coral cover is measured by determining the increase in the cover of hard corals.
- The hard coral cover in northern Great Barrier Reef had reached 36% while that in the central region had reached 33%.
- Meanwhile, coral cover levels declined in the southern region from 38% in 2021 to 34% in 2022.
- The high level of recovery is fueled by the increase in the fast-growing Acropora corals, which are a dominant type in the Great Barrier Reef.
- Incidentally, these fast-growing corals are also the most susceptible to environmental pressures such as rising temperatures, cyclones, pollution, crown-of-thorn starfish (COTs) attacks which prey on hard corals and so on.
- Also, behind the recent recovery in parts of the reef, are the low levels of acute stressors in the past 12 months — no tropical cyclones, lesser heat stress in 2020 and 2022 as opposed to 2016 and 2017, and a decrease in COTs outbreaks.
- The biggest threat to the health of the reef is climate change-induced heat stress, resulting in coral bleaching.
- Despite several global initiatives sea temperatures are predicted to increase by 1.5°C to 2°C by the time the century nears its end.
- According to the United Nations assessment in 2021, the world is going to experience heating at 1.5°C in the next decade, the temperature at which bleaching becomes more frequent and recovery less impactful.
- In recent times mass bleaching events have become more frequent.
- The first mass bleaching event occurred in 1998 when the El Niño weather pattern caused sea surfaces to heat, causing 8% of the world’s coral to die.
- The second event took place in 2002. But the longest and most damaging bleaching event took place from 2014 to 2017.
- The aerial surveys by AIMS included 47 reefs and coral bleaching was recorded on 45 of these reefs.
- While the levels were not high enough to cause coral death it did leave sub-lethal effects such as reduced growth and reproduction.
SOURCE: THE HINDU,THE ECONOMIC TIMES,MINT