A new study says that the Great Barrier Reef has lost as much as 50% of its coral cover in the past 3 decades, as climate change accelerates the damage.
The study comes from researchers at the ARC Centre of Excellence for Coral Reef Studies, based in Queensland, who have been studying the health and populations of coral reefs between 1995 and 2017.
Authors of the study say that coral reef populations on the Great Barrier Reef have declined by 50% over the past 3 decades, which impacts the 1,500 species of fish and 411 species of coral and other marine life that rely on the health of the reef to survive.
Scientists noted four significant bleaching events since 1995 from warmer water, an increase in the sediment and salinity of the water, a number of tropical cyclones, as well as threats to habitats from crown of thorns starfish that has contributed to a major decline in the reef’s health.
“We found the number of small, medium and large corals on the Great Barrier Reef has declined by more than 50% since the 1990s,” co-author of the report, Terry Hughes said.
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Andy Dieztel, doctorate with the ARC Centre of Excellence for Coral Reef Studies added that “a vibrant coral population has millions of small, baby corals, as well as many large ones – the big mamas who produce most of the larvae.”
“Our results show the ability of the Great Barrier Reef to recovery – it’s resilience – is compromised compared to the past, because there are fewer babies, and fewer large breeding adults,” Dieztel continued to explain.
Marine biologist Terry Hughes has said that “we used to think the Great Barrier Reef is protected by its sheer size, but our results show that even the world’s largest and relatively well-protected reef system is increasingly compromised and in decline.”
Hughes added that “if we can control warming somewhere between 1.5-2C, as per the Paris agreement, then we’ll still have a reef… if we get to 3-4C because of unrestrained emissions, then we won’t have a recognisable Great Barrier Reef.”
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Coral reefs are particularly vulnerable to the side effects of climate change due to their lack of resilience to changes in sea temperatures, as well as a low tolerance to changes in the salinity levels of its environment.
Authors of the report say that “the potential for recovery of older fecund corals is uncertain given the increasing frequency and intensity of disturbance events… the systematic decline in smaller colonies across regions, habitats and taxa suggests that a decline in recruitment has further eroded the recovery potential and resilience of coral populations.”
