Signs of life for stricken coral reef

New research from the Southern Cross University has detailed ‘remarkable growth’ of the southernmost community of coral in the Great Barrier Reef.

The research, led by doctoral researcher Kay Davis, detail a ‘completely unexpected’ finding of a coral ecosystem calcification increase of 400 per cent between 2014 to 2017.

Her team analysed the chemistry of water samples to measure whether coral and algae were growing or declining and at what rate, to determine how the ecosystem compares to previous studies conducted in the 1970s and throughout the 2000s.

“A devastating cyclone hit the One Tree Island reef in 2009, and no metabolic recovery was detected even five years after. In 2014, calcification had declined at One Tree Island by 75 per cent, and we expected this trend to continue due to ocean acidification inhibiting coral recovery. However, we found that the coral ecosystem has completely recovered from this cyclone event after eight years,” Ms Davis said.

“Not only did our water chemistry results show that calcification was recovering, but there was a visible increase in the amount of coral as well, with coral cover increasing to 30-40 per cent. However, we are still seeing an increase in organic productivity as well, which should continue to be monitored in the future."

“There were three studies after the cyclone and each one of them showed a decreasing trend in the coral growth in the area, so we expected the trend to continue,” she said.

The ocean is warming and acidifying so we wouldn’t think the coral would be able to fight that.”

Ms Davis said the recovery highlighted the volatility in Great Barrier Reef waters.

“It’s not unusual for reefs to recover, reefs have been recovering from stress events for many years, but as we see the effects of climate change we’re seeing that recovery is more difficult,” she said.

“One Tree Island is a special case because it was given that time and it remained relatively isolated from humans and human impact, apart from the global impact of climate change.”

She compared the remarkable recovery in the southern reef island with the example of Lizard Island, on the northernmost end of the Great Barrier Reef.

In that case the surrounding reef has now been largely overtaken by algae after most of its coral was killed off in the major 2016 bleaching event which affected large parts of the northern end of the Great Barrier Reef.

Ms Davis’ research into the Lizard Island situation was published in the Journal of Geophysical Research: Oceans, while her research highlighting the situation at One Tree Island was published in the journal Frontiers in Marine Science.

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