Scientists amazed at 400-year-old giant coral thriving in Great Barrier Reef

Scientists have described their surprise at the discovery of a 400-year-old giant Porites coral discovered in the Great Barrier Reef.

The “exceptionally large” brown and cream coloured coral was spotted off the coast of Goolboodi (Orpheus Island), Queensland, Australia, and is estimated to be one of the oldest corals in the Great Barrier Reef – between 421 and 438 years old.

It was discovered by a group of scientists and community members participating in a marine science course earlier this year. The group determined that it was the widest known Porites coral in the Great Barrier Reef measuring 10.4 metres at its base, and that it was the sixth tallest, measuring 5.3 meters high. The hemispherical coral is roughly the same size as a modern double-decker bus.

Dr Adam Smith, lead author of the field note on the discovery and adjunct professor at James Cook University, said: “It’s like a blog of apartments. It attracts other species. There’s other corals, there’s fish, there’s other animals around that use it for shelter or for feeding, so it’s pretty important for them.”

He added: “It’s a bit like finding a giant redwood tree in the middle of a botanic gardens.”

The group determined that the coral belonged to the genus Porites, a common type of coral worldwide, with 16 species, and believe that it is either belongs to Porites lutea (hump or pore coral) or Porites lobata (lobe coal).

Through consultation with the traditional custodians of area, the Manbarra Traditional Owners, it was decided that this specific coral would be named Muga dhambi, meaning big coral. The group said the name was important to communicate traditional knowledge, language and culture to future tourists, scientists and students.

It is thought that the coral went undiscovered for so long as it was located in a relatively remote, rarely visited and highly protected Marine National Park zone.

“Over the last 20 or 30 years, no one has noticed, or observed, or thought it newsworthy enough to share photos, or document, or do research on this giant coral,” Dr Smith said.

The team of citizens and scientists determined that the coral was very healthy, with 70 per cent live coral cover, as well as live coral rock and microalgae. No observations of disease, coral bleaching or recently deceased coral were recorded.

The coral’s age was estimated based on linear growth models and suggests that it has survived major oceanic disturbances including invasive species, bleaching events, severely low tides and a number of cyclones.

The field note said: “The cumulative impact of almost 100 bleaching events and up to 80 major cyclones over a period of four centuries, plus declining nearshore water quality contextualise the high resilience of this Porites coral”.

Looking to the future, concerns for the wellbeing of the Muga dhambi coral mirror those of the Great Barrier Reef as a whole – climate change, declining water quality, over-fishing and coastal development.

But Dr Smith seems hopeful. He said that most species of coral in the Great Barrier Reef live to around 450 or 460 years, and survive cyclones and coral bleaching events.

“It’s obviously an old resilient coral,” he added.