Reef rescue

French and Australian scientists are working together to understand how climate change is affecting reef sharks in French Polynesia, why corals in New Caledonia can survive extremes of temperature and acidity, and what fish markets mean for reef health.

Baby sharks

On Mo’orea in French Polynesia, Dr Jodie Rummer leads a project studying baby sharks to see how they will cope with climate change.

“Healthy reefs need healthy predators,” Jodie says. “And healthy predators need healthy reefs.”

After overfishing, climate change is the greatest threat to sharks. Because they take a long time to mature and produce relatively few young, they will be slow to adapt to warmer oceans, greater acidity and less oxygen.

The Physioshark project is a collaboration of Jodie and colleagues at James Cook University with Dr Serge Planes and other researchers at the Centre of Island Research and Environmental Observation (CRIOBE) in French Polynesia.

Dr Jodie Rummer studies baby sharks in French Polynesia.
Credit: Tom Vierus

Recently they have been conducting experiments on newborn blacktip reef and sicklefin lemon sharks to study their response to stressful events such as being chased by predators or getting caught in nets.

The project also involves outreach and education to communities in French Polynesia, where sharks play a significant role in local culture and healthy marine ecosystems are vital for fishing and tourism.

Hope for coral

A reef system in New Caledonia may hold the secret of survival for coral in a warming world. In the shallow mangroves off the island of Bourake, researchers are studying corals that survive in “climate change–like conditions”.

“We have found more than 50 species of coral thriving here in seawater conditions like what we expect for the end of the century: more acidic, warm, oxygen-depleted water,” says Dr Riccardo Rodolfo-Metalpa of the Institut de Recherche pour le Developpement (IRD). “We want to understand if this ability to survive is genetic and, most importantly, if other corals will be able to survive climate change.”

Riccardo and his IRD colleague Dr Fanny Houlbreque are working in collaboration with Associate Professor David Suggett and others at the University of Technology Sydney in a project funded through the French government’s Fond Pacifique. What they learn will help New Caledonians manage their reefs into the future, as well as offering lessons for reefs in Australia and around the world.

“This will fundamentally change our understanding of how climate change will impact coral reefs in the next 50 years and even beyond,” says Riccardo.

Market forces

Being close to a fish market is one of the most important factors in overfishing of coral reefs, Professor Joshua Cinner from James Cook University and Professor David Mouillot from the University of Montpellier have found.

“The bigger the market and the closer to the reef, the greater the pressure on fish stocks,” says Joshua.

Understanding the social, economic and cultural needs of the people who use reefs is the key to influencing their behaviour to sustain healthy reefs, says David.

“It’s only by drawing together human geography, common property, anthropology, conservation policy and ecology that we have been able to tease these factors out.”

Banner Image: The “extreme corals” of Bourake may hold out hope for coral in the face of climate change. Credit: Stephanie Gardner