Global warming could result in large areas of the Great Barrier Reef being poisoned by algae by 2050, study warns

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Researchers have found that a 'weed-like' algae is killing corals in the Great Barrier Reef because of increased carbon dioxide levels in the atmosphere. 

The study found that if the world continues to emit carbon dioxide at the same rate as it is doing now, reef building corals will suffer significantly by 2050 and die off by 2100. 

Researchers knew that increased carbon dioxide had an effect on seaweed behavior but haven't explained how this happens until now.

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The research has global implications because one of the seaweed species they studied that causes the most damage is a common brown algae found in coral reefs all over the world

The research, based at Griffith University in Queensland, Australia, discovered that algae kills the corals through a potent chemical compound that poisons them.

Professor Guillermo Diaz-Pulido of Griffith's School of Environment and co-author of the study, said: 'This is a major step forward in understanding how seaweeds can harm corals and has important implications for comprehending the consequences of increased carbon dioxide emissions on the health of the Great Barrier Reef.

'For the algae to grow they need light and CO2 just like any other plant, and because algae in the future would be exposed to much more CO2 in seawater we wanted to know to what extent the CO2 would affect some of the things algae do, the physiology and the interaction with animals.' 

The research, conducted at Heron Island on the southern end of the reef, used underwater experiments and lab experiments.

The research, conducted at Heron Island (pictured) on the southern end of the reef, used underwater experiments and lab experiments

The researchers tested algae samples in the lab to observe the effect that carbon dioxide had on algae. 

They exposed algae sample to two levels of carbon dioxide: ambient and high, with ambient reflecting current levels and high reflecting levels projected for 2100 under a model by the Intergovernmental Panel for Climate Change. 

The research, published in the journal Scientific Reports, found that higher levels of carbon dioxide made compounds produced by the algae more potent - and some species of algae produce more of these poisonous chemicals than others.

The research found that higher levels of carbon dioxide made compounds produced by the algae more potent - and some species of algae produce more of these poisonous chemicals than others

Professor Mark Hay, a professor of environmental science and technology at the Georgia Institute of Technology and a co-author of the study, said: 'What we’ve discovered is that some algae produce more potent chemicals that suppress or kill corals more rapidly. 

'This can occur rapidly, in a matter of only weeks.

'If the algae overtake the coral we have a problem which contributes to reef degradation, on top of what we already know with coral bleaching, crown of thorn starfish outbreaks, cyclones or any other disturbance.'

Professor Diaz-Pulido said that the research has global implications too because one of the seaweed species they studied that causes the most damage is a common brown algae found in coral reefs all over the world. 

'That’s a problem because if these algae take advantage of elevated CO2 in seawater that’s even more a matter of concern,'said Professor Diaz-Pulido.

'The scale of the problem is so big removing a bunch of seaweed from the reef isn’t going to do much because it just regrows and regenerates, so I think the way to address this really is to reduce the levels of CO2 in the atmosphere.'