Australian scientists have proposed covering endangered coral reefs with shade cloth as part of “last resort” measures to protect parts of the iconic Great Barrier Reef.
The proposal, in a paper published today, also includes using low-voltage electrical currents to stimulate coral growth and defend against the worsening impact of heat stress. The paper, in the journal Nature Climate Change, says the pace of global warming is unparalleled in 300 million years and has led to temperature rises of at least 2 degrees Celsius and a 60-per-cent increase in surface ocean acidity over the past three centuries. Professor Ove Hoegh-Guldberg of Queensland University, Australia, writing with Greg Rau from the University of California and Elizabeth McLeod from The Nature Conservancy, calls for “unconventional, non-passive methods to conserve marine ecosystems”. “A much broader approach to marine management and mitigation options, including shade cloth, electrical current and genetic engineering must be seriously considered,” the paper says. “The magnitude and rapidity of these changes is likely to surpass the ability of numerous marine species to adapt and survive.” The paper proposes a range of possible future options for ocean management, including selective breeding and adding base minerals and silicates to the water to neutralise acidity. The Barrier Reef includes about 900 coral formations stretching along 1,600 miles off Australia’s east coast. Its coral formations and marine life attract about 2 million visitors each year. The shade cloths proposed in the report would be anchored with ropes and float on the water surface to protect the corals from sunlight. In an experiment performed in Queensland several years ago, researchers deployed 15-feet by 15-feet sheets of plastic mesh, similar to those used by gardeners to protect vegetable patches. Professor Hoegh-Guldberg told the Daily Telegraph the technique was useful for protecting small patches of coral but would not “save the Great Barrier Reef” as a whole. “We are recommending looking at these technologies because at current rate of warming we may need to use them in 20 over 30 years time,” he said. “We should test them now and see which ones work. Shading is not a strategy that can be used across hundreds of kilometres of the reef. But it might – at a local level – be able to influence how many corals die.” Earlier Professor Hoegh-Guldberg told The Conversation website: “It’s unwise to assume we will be able to stabilise atmospheric carbon dioxide at levels necessary to prevent ongoing damage to marine ecosystems.” “In lieu of dealing with the core problem – increasing emissions of greenhouse gases – these techniques and approaches could ultimately represent the last resort.” A separate report by Australian scientists found climate change is having a dramatic impact on the country’s marine life and causing tropical fish to turn up in the chilly southern waters around Tasmania. The report, released last week, says south-east Australia has become “a global warming hot spot” and damage to coral reefs is becoming more severe. It says climate change has caused worsening ocean acidification and coral bleaching as well as a southward migration of seaweeds, phytoplankton, zooplankton and fish. “There is now striking evidence of extensive southward movements of tropical species in south-east Australia, declines in abundance of many temperate species, and the first signs of the effect of ocean acidification on marine species with shells,” says the report, by 80 scientists and led by the national science body, CSIRO. The report found sea surface temperatures had increased by one degree centigrade over the last century and that the east coast of Tasmania and parts of Western Australia had the highest increases. “The rate of temperature rise in Australian waters has accelerated since the mid-twentieth century; from 0.08 degrees/decade in 1910-2011 to 0.11 degrees/decade from 1950-2011,” the report says. “Sea levels are rising around Australia, with fastest rates currently in northern Australia.” Professor David Booth, a marine ecologist at the University of Technology Sydney, said tropical fish have been shifting towards Tasmania for 30 or 40 years but the flow has increased in the past 10 years. “In this case the rapidity of the change is probably fairly unprecedented,” he told ABC Radio. Source: http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/australia/9487095/Underwater-umbrellas-should-be-used-to-protect-Great-Barrier-Reef-says-report.html