Persian Gulf's coral reefs may hold clues to surviving climate change

Transcription

1 Persian Gulf's coral reefs may hold clues to surviving climate change By Scientific American, adapted by Newsela staff on Word Count 996 This picture taken at Australia's Great Barrier Reef shows bleached branching coral in the foreground and normal branching coral in the background. Photo: Acropora/Wikimedia Commons The Persian Gulf's coral reefs only have 10 percent of the diversity found in the Indian Ocean or on the Great Barrier Reef. But the murky waters off the United Arab Emirates (UAE) coast might hold something even more precious: clues that could one day help coral reefs around the world survive the effects of warmer waters caused by climate change. Most coral reefs in temperate climates can only withstand temperatures as high as 29 degrees Celsius (84 degrees Fahrenheit) before they expel the algae living in their tissue. This "bleaching" process causes them to turn white. More importantly, it increases their vulnerability to disease and death. The algae and coral have a symbiotic relationship the coral needs algae for food. However, scientists have found corals in the Persian Gulf reefs that can tolerate water temperatures as high as 36 degrees C (97 degrees F) warmer than the highest predictions for the next century. John Burt, a marine biologist at New York University, says the Persian Gulf corals "offer hope." He thinks their genetic mechanisms could help other corals survive warmer temperatures.

2 Climate Change On The Reefs Pollution, overfishing and coastal development have cost coral reefs up to 50 percent of their cover in some places. Still, most scientists say climate change poses the biggest threat in the future. Warming waters spark bleaching events. In addition, ocean acidification caused by oceans absorbing carbon dioxide from the atmosphere (also blamed on climate change) makes it harder for corals to calcify. Without enough calcium, their shells cannot grow enough and thrive. The National Oceanic and Atmospheric Administration warned that warming waters could lead to a global bleaching event in 2015 the third one in the past two decades. Scientists believe most coral reefs will be under threat by They say corals and their symbionts, which are single-celled algae, have been adapting too slowly to keep pace with the rate of global warming. Scientists studying the Persian Gulf are challenging this idea. They have shown that coral reefs can bounce back from bleaching events faster than previously thought. They may even be able to acquire heat-tolerant symbionts in a relatively short time. It s not all doom and gloom for corals, says Andrew Baker, a marine biologist at the University of Miami. Adapting To Changing Conditions Corals have a repertoire of responses, Baker says. The question has been, well, how quickly can those responses arise? I think we are now getting to this idea that actually, in some cases, these mechanisms can arise very quickly, within a few years. Baker s work prompted Burt and several of his peers to spend the last three years surveying reef sites off the coasts of the UAE and Oman. They discovered a new type of algae with heat-tolerant traits. Their research suggests that the heat tolerance in certain corals and algae is unique to the Persian Gulf. The researchers demonstrated that this new organism was the most commonly found symbiont throughout the Persian Gulf. They say it likely adapted to play a new role in the gulf s harsh conditions, but they have not determined whether that happened by evolution or if the algae was brought in by currents from outside the region and survived a selection process. If they haven t evolved in the gulf, they must be present in other populations in low numbers elsewhere in the world," says University of Southampton professor Jörg Wiedenmann. "This would be good news because that would mean corals elsewhere might have these (heat) tolerant individuals among them.

3 Answers May Lie Elsewhere In theory, if symbionts exist elsewhere, then corals faced with bleaching could switch them on as temperatures rise. "That could compensate for the some of the warming we are expecting to see this century," Baker says. But he also notes that water temperatures are predicted to climb beyond such tolerance. Scientists do not know if corals "can continue to deal with increasing temperatures or whether this is a kind of a stopgap measure. community will provide a perfect solution. They are also doubtful about finding answers in the Persian Gulf. Due to the gulf s limited diversity and changing seasons, some experts think researchers would be better off looking for answers in more temperate regions. Some have suggested the Reef expert Ove Hoegh-Guldberg says the Persian Gulf work is intriguing, but it was misplaced to hope that the thermal tolerance would offer hope for reefs in temperate climates. Evolution is too slow when it comes to long-lived organisms such as corals. Guldberg also pointed out that the symbionts are not the only ones that need to evolve. It s the combination of the host and symbiont that needs to adapt rapidly to changing sea temperatures, he wrote. Reintroducing Corals Is Risky Such doubts have done little to dampen the enthusiasm for using genes from the Persian Gulf reefs in future conservation strategies. Bernhard Riegl of Florida's Nova Southeastern University wants to begin moving corals to the Indo-Pacific. He plans to introduce heat-adaptation through hybridization with resident genetic material. Baker has considered introducing heat-tolerant symbionts in nurseries and then reseeding areas at risk. Others want to crossbreed gulf corals with those in temperate climates. No one denies that these strategies involve risks they are costly and could introduce invasive species and disease. The reintroduced corals might not even cope well with new environmental conditions. But experts like the Australian Institute of Marine Science's Madeleine van Oppen argue that it is time to explore human-assisted evolution. When I first started talking about it, people would say, Oh God, that will never work. You can never do it at the scale required, van Oppen wrote. People still have those concerns, but they can see that it s important to develop the tools and to assess what is actually possible.

4 Quiz 1 Select the paragraph from the section "Climate Change On The Reefs" that explains the biggest problem facing coral reefs today. 2 Which paragraph from the article describes the important discovery highlighted in the article? Corals have a repertoire of responses, Baker says. The question has been, well, how quickly can those responses arise? I think we are now getting to this idea that actually, in some cases, these mechanisms can arise very quickly, within a few years. Baker s work prompted Burt and several of his peers to spend the last three years surveying reef sites off the coasts of the UAE and Oman. They discovered a new type of algae with heat-tolerant traits. Their research suggests that the heat tolerance in certain corals and algae is unique to the Persian Gulf. In theory, if symbionts exist elsewhere, then corals faced with bleaching could switch them on as temperatures rise. "That could compensate for the some of the warming we are expecting to see this century," Baker says. But he also notes that water temperatures are predicted to climb beyond such tolerance. Scientists do not know if corals "can continue to deal with increasing temperatures or whether this is a kind of a stopgap measure. 3 Information from which of these sub-headings is LEAST important in understanding or shaping the main idea of this article? "Climate Change On The Reefs" "Adapting To Changing Conditions" "Answers May Lie Elsewhere" "Reintroducing Corals Is Risky"

5 4 If this article were to be rewritten to focus on the risks associated with changing the natural environment, which paragraph would be MOST useful? Such doubts have done little to dampen the enthusiasm for using genes from the Persian Gulf reefs in future conservation strategies. But experts like the Australian Institute of Marine Science's Madeleine van Oppen argue that it is time to explore human-assisted evolution. Reef expert Ove Hoegh-Guldberg says the Persian Gulf work is intriguing, but it was misplaced to hope that the thermal tolerance would offer hope for reefs in temperate climates. Evolution is too slow when it comes to longlived organisms such as corals.

6 Answer Key 1 Select the paragraph from the section "Climate Change On The Reefs" that explains the biggest problem facing coral reefs today. Paragraph 4: Warming waters spark bleaching events. In addition, ocean acidification caused by oceans absorbing carbon dioxide from the atmosphere (also blamed on climate change) makes it harder for corals to calcify. Without enough calcium, their shells cannot grow enough and thrive. The National Oceanic and Atmospheric Administration warned that warming waters could lead to a global bleaching event in 2015 the third one in the past two decades. 2 Which paragraph from the article describes the important discovery highlighted in the article? Corals have a repertoire of responses, Baker says. The question has been, well, how quickly can those responses arise? I think we are now getting to this idea that actually, in some cases, these mechanisms can arise very quickly, within a few years. Baker s work prompted Burt and several of his peers to spend the last three years surveying reef sites off the coasts of the UAE and Oman. They discovered a new type of algae with heat-tolerant traits. Their research suggests that the heat tolerance in certain corals and algae is unique to the Persian Gulf. In theory, if symbionts exist elsewhere, then corals faced with bleaching could switch them on as temperatures rise. "That could compensate for the some of the warming we are expecting to see this century," Baker says. But he also notes that water temperatures are predicted to climb beyond such tolerance. Scientists do not know if corals "can continue to deal with increasing temperatures or whether this is a kind of a stopgap measure. 3 Information from which of these sub-headings is LEAST important in understanding or shaping the main idea of this article? "Climate Change On The Reefs" "Adapting To Changing Conditions" "Answers May Lie Elsewhere" "Reintroducing Corals Is Risky"

7 4 If this article were to be rewritten to focus on the risks associated with changing the natural environment, which paragraph would be MOST useful? Such doubts have done little to dampen the enthusiasm for using genes from the Persian Gulf reefs in future conservation strategies. But experts like the Australian Institute of Marine Science's Madeleine van Oppen argue that it is time to explore human-assisted evolution. Reef expert Ove Hoegh-Guldberg says the Persian Gulf work is intriguing, but it was misplaced to hope that the thermal tolerance would offer hope for reefs in temperate climates. Evolution is too slow when it comes to long-lived organisms such as corals.