The Great Southern Reef stretches more than 1,400 miles off the coast of Australia, and is suffering an ecological disaster.
Almost all of the kelp forests in a section of the reef have become extinct following a 2011 heatwave that killed 43% of the kelp. The results of a study published in the journal Science on Friday show that there has been no sign of recovery from the kelp forest five years after the heatwave, writes Ben Rosen for The Christian Science Monitor.
Kelp forests extinct along 62 miles of reef
Study lead author Thomas Wernberg of the University of Western Australia’s Ocean Institute released a statement in which he announced that the kelp forests were extinct along a section of coastline some 62 miles in length. Their extinction shows how sensitive the ecosystem is, and reveals the devastating effects of even a slight rise in water temperatures.
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The Indian Ocean is warming twice as fast as the rest of the waters around the globe, and currents flow from it to the Great Southern Reef. The devastation of its kelp forests could prove to be a portent of things to come in other parts of the world’s oceans, including off Japan and Europe.
“They have provided alarming and detailed evidence for one of the most dramatic climate-driven ecosystem shifts ever recorded,” Adriana Verges, a marine ecologist at the University of New South Wales, said of the study.
Future looks bleak for Great Southern Reef
According to Ed Yong of The Atlantic, the ocean looks set to get warmer in future. It is also likely that extreme weather events such as heat waves will happen more often. “The kelps will recede further southwards until they can’t any more. Kelps need to fasten themselves to rocks, and at some point, ‘they’ll run out of habitat,’ says Wernberg. ‘There’ll be no rock, just deep water until you get to Antarctica. We’ll likely see local extinctions over large areas.”
The Great Southern Reef runs from Brisbane in eastern Australia to Kalbarri in western Australia. The kelp forests stretch to the surface, with tree-like branches, and are known as a diversity hotspot. 30-80% of species that live there are not found anywhere else on the planet.
According to a report in The Atlantic, rock lobster and abalone fisheries along the reef bring in 4 times as much money as all of the commercial fishing operations in the Great Barrier Reef. In fact the study claims that the Great Southern Reef, and the communities that rely on it, bring $10 billion into the Australian economy. This money is under threat due to rising water temperatures.
Some see hope for other kelp forests
Due to the fact that the kelp forests died off, the fishes, invertebrates and ocean plants that depend on them also died off. Warmer waters encouraged the growth of turf seaweed and the arrival of parrotfish and rabbitfish. However these tropical fishes eat any kelp that starts to regrow.
Wernberg says that kelp forests in the south of the reef are healthier. However he is worried that further heat waves could lead to more destruction. One way that scientists could reduce the effects of warmer water is by regulating other factors like sewage run-offs, which also weaken kelp.
Other kelp forests have shown better resilience. Some areas located off Tasmania did not lose significant amounts of kelp despite the longest and hottest heat wave on record, caused by the El Nino phenomenon.