New volcanic world reveals the key to reef rejuvenation

11 December 2019

Coral researchers from Museum of Tropical Queensland and James Cook University have discovered how the reefs and marine environment around one of the world’s newest islands were able to regenerate after a natural disaster.

The island in the South Pacific known as Hunga Tonga Hunga Ha’apai (HTHH), lies 60kms west of the main Tongan archipelago, and stands over 200m high resulting from an underwater volcanic eruption in 2015.

The team travelled to the island in 2018 to investigate the effects of the eruption on nearby coral reefs. The project also involved collaborators from the NASA Goddard Space Flight Centre, who helped reconstruct the environmental conditions present at the time of the eruption.

Senior Curator of Corals, Queensland Museum Network and James Cook University, Dr Tom Bridge said that the reefs were surveyed not only to examine the effects of the eruption, but also to understand how new reefs begin forming on brand habitat that is now available around the new island.

Some parts of the reef were totally annihilated by the blast” Dr. Bridge said. “They were completely destroyed with huge chunks of reef turned over – you could still identify individual coral species in situ but covered in black sediment, and often upside down.,” Dr Bridge said.

“However, in the four years since the eruption occurred and the island was created, the reefs have shown incredible recovery from what was a massive environmental disturbance.”

PhD candidate Patrick Smallhorn-West from ARC Centre of Excellence for Coral Reef Science at James Cook University said the key factor in recovery of this isolated reef system was likely surviving ‘refuge populations’, or small pockets reef community that somehow weren’t as affected by the blast. “While most of the reef area was completely annihilated, in one small section that had been sheltered from the blast we found high coral cover and many large mature coral colonies, this was a well-established reef system that had clearly been unaffected by the eruption.”

“These refuges may have provided a source of larvae that repopulated reefs around the rest of the island. This was suggested by the large number of juvenile corals of the same species as the refuge area but younger than the eruption event, which were repopulating the destroyed reef.” Patrick said.

“Importantly, the reef’s ability to ‘bounce-back’ was almost certainly aided by the lack of human activities around the island. The fact that it is an incredibly isolated environment would have also played to its advantage.”

Queensland Museum Network CEO Dr Jim Thompson said expeditions such as these are vital to help us understand more about reef rejuvenation a little closer to home.

Hunga Tonga - Hunga Ha’apai is truly a unique environment, however this expedition has reinforced the importance that living coral refuges and reduced human intervention can play a part in rejuvenating our own Great Barrier Reef.”

The research, published in Coral Reefs talks in depth about the destruction and recovery of the reef around Hunga Tonga - Hunga Ha’apai and what this can indicate about rejuvenation of coral ecosystems around the world.

Media Contacts: Andrea Hughes 07 4726 0604

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