CORAL REEFS IN GREAT BARRIER REEF

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.

Issues:

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

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