Kimberley corals are true Aussie battlers

Zoe collecting samples for further molecular analysis. Photo WA Museum

While coral reefs around the world are feeling the heat, little-known reefs in Australia’s Kimberley region are prospering, despite living in some of the toughest conditions—and scientists aren’t yet sure why.

The discovery has particular significance this summer with fears of a severe coral bleaching event to hit our northern waters—the result of steadily rising sea temperatures and a strong seasonal El Niño.

WA researchers have found that while coral reefs all around the world are feeling the heat of rising temperatures, some inshore reefs in the Kimberley region’s Bonaparte Archipelago are prospering, despite living in some of the toughest conditions.

“Widespread coral bleaching is predicted to occur in the Kimberley region over the coming summer,” said Dr Zoe Richards of the Western Australian Museum. “So we will be able to study whether the corals living in these very changeable inshore areas have an inherent capacity to resist bleaching when compared with corals living further out to sea.

“The most outstanding feature of these Kimberley corals is their health,” Zoe says.

“Despite repetitive low-tide exposure to extreme air temperatures, light, rainfall, high sea-surface temperatures, the Kimberley corals are exceptionally healthy and showing few signs of stress such as coral bleaching or disease.”

In an area with “huge tides, bad water visibility, strong currents, and of course crocodiles,” Zoe has exposed a biological treasure trove, which she will explore further with the help of a Research Fellowship from Curtin University.

Zoe discovered several species of coral that had never been recorded in Australia, and has so far documented more than 225 species living in the Bonaparte intertidal zone (the region that is covered at high tide but exposed during low tide).

This was far more than the dozen or so species Zoe says might have been expected to survive there.

The Bonaparte study was conducted in collaboration with colleagues from Curtin University, the Museum of Tropical Queensland, and the University of Western Australia.

Finding out how these corals are coping, while many elsewhere are dying, may shed light on the resilience of different species to climate change. It may also provide options for coral relocation, which is one of the chief conservation methods considered for restoring damaged reefs.

The timing of low tide (when the corals are exposed) in the early morning and late afternoon may help offset some of the stress, along with adaptations such as producing large amounts of mucus to act as a natural sunscreen.

“At high tide, the naturally high levels of sediment in the water stirred up by the strong currents may also help protect the corals from some of the light – unlike some other reefs where sediment in the water can stop corals from getting enough light,” Zoe says.

She suspects these corals may also be making the best of the turbulent water, capturing more floating food with their tiny tentacles, rather than relying on getting most of their energy from sunlight.

Corals in clearer waters tend to use their tentacles to feed only at night – so this is one of the many areas Zoe hopes to investigate further.

“This study has raised lots of interesting questions, which we haven’t really had the chance to investigate yet because the Kimberley is such a remote area,” says Zoe. “The Fellowship will go a long way in helping me answer some of these.”

The study was conducted under contract to INPEX as part of environmental monitoring for the Ichthys Gas Field Development Project and was published in the journal PLOS One in February. It complements a larger, on-going investigation into the marine life of the Kimberley that is being conducted by the Western Australian Museum in partnership with Woodside Energy.

Zoe was the WA winner of Fresh Science, a national program that helps early-career researchers find and share their stories of discovery. Now in its 18th year, Fresh Science is building a cadre of skilled Australian science communicators. In 2015, the program ran in every mainland state, with 180 early-career researchers nominating for the six Fresh Science events in Melbourne, Townsville, Brisbane, Perth, Adelaide and Sydney.

Fresh Science WA was held at the Western Australian Museum (training day) and Brisbane Hotel (challenge event) and was supported by the Western Australian Museum, Curtin University, Edith Cowan University, Murdoch University, the University of Western Australia and the University of Notre Dame, Australia.