Concern for the Great Barrier Reef off the coast of the Australian state of Queensland: Due to significantly increased water temperatures, the fifth mass bleaching of corals in just eight years has been confirmed in this natural wonder. The responsible authority, the Great Barrier Reef Marine Park Authority (GBRMPA), announced this on Friday. Experts had already reported a few days ago that due to the recent marine heat wave, a 1,100 kilometer long area stretching from Lizard Island to the Keppel Islands resembled an undersea ghost forest.
Aerial photographs have now shown that the new coral bleaching is already very widespread. However, further studies directly in the water are needed to accurately assess the severity of the mass bleaching, the GBRMPA wrote.
The massive reef is so large that it can even be seen from space. The living organism stretches 2,300 kilometers off the northeast coast of Australia and is considered one of the most species-rich habitats on earth. Hundreds of coral species, 1,500 species of fish and 4,000 different species of molluscs are found here.
“The Great Barrier Reef is suffering massively from heat stress,” warned Laura Puk, an expert on corals and mangroves from WWF Germany. “Severe coral bleaching causes coral death and if this occurs in short intervals, a reef has no chance of recovering.” This eighth bleaching event since 2016 is devastating for the World Heritage Site.
Puk explained the phenomenon as follows: When coral polyps are stressed by prolonged heat waves, they reject the colored algae that provide them with food and with which they otherwise live together in a community for mutual benefit. They remain pale and white or produce bright colors in a last attempt to protect themselves. “Without their symbiosis partners, the corals ‘starve’ and die,” explained Puk. The result is white limestone skeletons that are soon overgrown by green-brown algae.
Marine conservationists say that only a quick change in the weather and a rapid cooling of the water can save the Great Barrier Reef. According to the WWF, every tenth of a degree of global warming avoided counts.
However, the Townsville-based GBRMPA stressed that not all is lost – and bleaching cnidarians does not necessarily lead to their death. The reef has already demonstrated its ability to recover from previous coral bleaching events or severe tropical cyclones. But one thing is certain, WWF Australia said: “Five mass bleaching events in eight years show that climate change is putting enormous pressure on the reef.”
