Chemical Technology May 2016

RENEWABLES

The zooxanthellae which infect corals can offer additional protection to their hosts. Infecting coral larvae with different species of symbiotic zooxanthellae conveys very different survival patterns. In other words, some combination of con- trolled stress during coral farming, and the introduction of appropriate zooxanthellae, will convey an optimum survival strategy for corals. The objective of all these researchers is to create a seed bank of gametes and fertilised embryos optimised for extreme environments which can be used to re-seed corals at risk of bleaching-related death. Zooxanthellae are much shorter-lived and have a faster reproductive lifecycle than do corals. Intentionally seeding entire ecosystems with hardier species of the microalgae could be a dramatic life-changer. In agriculture, producing heat- and drought-tolerant crops is crucial to climate change adaptation. Billions of the world’s poorest are subsistence farmers and, without new crops, they will suffer famine. Even as governments as diverse as those in Australia, China, Brazil and the US refuse to acknowledge the true extent of the damage global warming is causing, they are also funding research to support adaptive response, such as new crop varieties produced to deal with reduced rainfall and hotter weather. The question is not whether such adaption techniques will work on coral reefs. It is whether the scientists working on the problemwill solve it fast enough to make a meaning- ful difference. Thirty percent of the world’s coral reef populations have already died from repeated bleaching. With millions of people depending for their livelihoods on the survival on the complex ecosystems that live on and in coral reefs, we can only hope that they solve the problem in time.

waters — a temperature that would normally kill corals. In parts of the ocean near Palau, the water is extremely acidic which should dissolve the carbonate skeletons of the corals living there. Except that it doesn’t. These particular corals are made up of a wide variety of ‘extremophil’ coral polyps and zooxanthellae. Interviewed for the journal, ‘Nature’, Steve Palumbi, a marine biologist as Stanford University in California, rec- ognised that these corals are a genetic wonder. “The real question is: how did they do that and can all corals do that?” Palumbi and others at the University of Hawaii at Manoa, are researching whether they can transfer these favourable genetic traits to other species. Genetic modification is prov- ing too controversial, and so the researchers are attempting to speed up evolution through selective breeding. One experiment run off the coast of Ofu Island in Ameri- can Samoa, has two populations of Acropora hyacinthus living in very different waters: one at 35 °C and the other at 29 °C. Samples from each were placed in controlled tanks and shocked with temperatures of over 3 °C above normal for four days. Both corals bleached, but the high tempera- ture corals survived longer and showed higher expression in a range of genes associated with thermal tolerance. Palumbi and his team believe that corals can ‘toughen up’ if raised in nurseries under more extreme conditions. Over the generations, they express these thermophile genes to a higher degree. Even better, once transplanted, these corals also do significantly better and grow faster than those raised in cooler pools. Other research by Hollie Putnam of the University of Hawaii shows that the larvae produced by corals subjected to stress have increased resilience to heat and ocean acidification. These tolerances are then passed on to their offspring as well. And that’s only part of the overall picture.

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Chemical Technology • May 2016