Researcher Pamela Kamya, who is a PhD student from Papua New Guinea.
Researcher Pamela Kamya, who is a PhD student from Papua New Guinea.

Halting the reign of destructive crown-of-thorns starfish

CROWN-of-thorns Starfish can wreak havoc on coral reefs, and new research from Southern Cross University shows juvenile starfish may grow faster as ocean acidification levels increase.

The destructive coral-eating starfish, which feed on pink 'coralline' algae in its infancy, were found to grow quicker in the high-CO2 ocean conditions predicted to occur before 2100.

Marine researchers Pamela Kamya (PhD student) and Associate Professor Symon Dworjanyn (University's National Marine Science Centre in Coffs Harbour) found ocean acidification caused the algal food to become easier to eat and more nutritious for the juvenile starfish.

Professor Dworjanyn said the crown-of-thorns starfish populations boom periodically and in some cases on the Great Barrier Reef, can cause more damage than ocean warming or cyclones.

"This species is causing destruction to coral reefs ...we were interested in how these starfish would fare in future ocean conditions ...starfish may become even more of a threat as a result of climate change”.

Professor Dworjanyn explained oceans are becoming more acidic as they absorb increasing concentrations of atmospheric carbon dioxide (CO2).

The scientists used a computer-controlled, marine climate change simulator which automatically injected CO2 to simulate ocean conditions predicted in the future.

"Surprisingly, the indirect effects of ocean acidification cause the starfish to grow faster as their algae food becomes more palatable and easier to eat,” Professor Dworjanyn said.

The higher the acidity the less the algae is defended against herbivores, he said.

What triggers outbreaks of adults is still a mystery.

Professor Dworjanyn said this was another reason humans need to reduce the amount of CO2 in the atmosphere.

"Coral reefs are already affected directly by climate change, indirect effects such as this may speed their decline and we need to take action,” he said.

Pamela Kamya said research into the crown-of-thorns starfish would help marine scientists understand and manage its impacts and protect these pristine coral reefs in Papua New Guinea, Australia and throughout the region.