Australia’s Great Barrier Reef is hit by the worst coral decline following mass bleaching in the two of its three regions over the last year.
According to a new report published by the Australian Institute of Marine Science (AIMS), the reef has experienced the largest and record-breaking annual decline in cover since the monitoring started 39 years ago.
Among all the regions, northern and southern regions are the most-affected as the widespread coral cover has dropped between a quarter and third after years of growth.
Mike Emslie, head of the institute's long term monitoring programme, said, “We are now seeing increased volatility in the levels of hard coral cover. This is a phenomenon that emerged over the last 15 years and points to an ecosystem under stress.”
According to AIMS findings, tropical cyclones and outbreak of crown-of-thorns starfish that feed on the coral, have been responsible for destruction of coral species, especially Acropora in recent months.
However, heat stress induced by climate change is the most significant reason for coral bleaching in 2024 and in the first few months of 2025.
The coral will die if it constantly experiences temperatures 1C above its limit for two months. Water temperatures around 2C will further reduce coral life expectancy to one month.
Moreover, weather patterns like El Niño also play an important role in bleaching events.
Given the alarming situation, the report warns of a tipping point where a coral cannot recover fast and face a “volatile” future.
The Great Barrier Reef is considered as the world’s largest living ecosystem, stretching from some 24,000 km off the coast of the northern state of Queensland.
The Australian government has put various efforts to save the largest biodiversity hub. The administration has initiated a crown-of-thorns starfish culling programme. The purpose of the initiative is to reduce the population of starfish by injecting them with vinegar or ox bile.
Despite the government's efforts, the United Nations Educational, Scientific and Cultural Organization (UNESCO) warns that the Australian icon is still in danger from sea pollution and ocean acidification.