HALF OF GREAT BARRIER REEF CORALS HAVE DIED SINCE 1990s

Australia's Great Barrier Reef has lost half of its coral population "across virtually all species" since the 1990s, according to a new study published, Deutsche Presse-Agentur (dpa) reported. 

The number of small, medium and large corals in both shallow and deeper water declined by more than 50 per cent between 1996 and 2017, researchers from Queensland's ARC Centre of Excellence for Coral Reef Studies found. Declines were particularly pronounced in the regions affected by the record-breaking temperatures that triggered mass bleaching in 2016 and 2017. 

The study, published in the Proceedings of the Royal Society B journal, found that the worst-affected species were the branching and table-shaped corals, which provide the structures important for reef inhabitants including fish. "The loss of these corals means a loss of habitat, which in turn diminishes fish abundance and the productivity of coral reef fisheries," the study states. 

Co-author Terry Hughes said the reef's ability to recover was also compromised compared to in the past, because there were fewer large breeding corals. "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," he said. The Great Barrier Reef is the world’s most extensive coral reef ecosystem and the habitat of threatened species such as the dugong and large green turtle. The researchers have attributed the decline of corals to climate change, which is "driving an increase in the frequency of reef disturbances such as marine heatwaves." "There is no time to lose - we must sharply decrease greenhouse gas emissions ASAP," the authors warned.