International reef symposium in Australia highlights latest research
By Summit Voice
SUMMIT COUNTY — It’s not easy these days being an optimist if you’re a coral reef researcher. Most recent studies suggest that ever-warmer and increasingly acidified oceans represent a death-spiral for many beloved reef ecosystems, with significant signs of decline already observed in the Caribbean and other ocean regions.
But some of the world’s leading marine scientists, gathered in Cairns, Australia for a quadrennial international reef symposium think there’s a good chance to preserve at least some important reefs — if we act now.
That could be critical not just for the reef ecosystems themselves, but for the 81 nations and 500 million people who depend on them.
“I’m an optimist – you have to be, to devote your life to this field,” said Dr. John Pandolfi, with the ARC Centre of Excellence for Coral Reef Studies and University of Queensland.
Despite scientific predictions that the current trajectory of human development will eliminate 90 per cent of the world’s coral reefs by the end of the century, Pandolfi considers it is still within our power to save 60 or 70 percent, provided humans can limit activities that drive corals to ruin.
Slowing the steady tide of global warming will take a while, and ocean temperatures are likely to rise significantly even if greenhouse gas emissions are drastically cut.
So a long-range strategy for preserving reefs, or at least enabling them to recover from heat-driven bleaching events, includes limiting more localized impacts like over-fishing and pollution.
Pandolfi has traced the story of the world’s reefs over more than 50 million years and is deciphering delicate signals from the past to reveal what doomed them in previous extinctions and how that compares with current observations of reefs.
“Corals themselves are remarkably resilient. They have stood up to several episodes of global warming and high CO2 in the past and bounced back, even from mass extinction events,” he said.
But the sobering fact is that it can take coral reefs up to ten million years to re-establish after a major extinction event, he says.
“That’s a long time to wait if your industries, communities and food supplies are dependent on reefs,” he explained.
The big issue today is that most of the world’s coral reefs face a ‘double whammy’ of accelerated global change combined with local stresses from pollution, runoff and overfishing. These local, man-made, factors were absent during previous world coral crises, he points out.
“Also, while corals have withstood hot climates and high CO2 in the past, we have so far been unable to identify any period in Earth’s history when CO2 levels rose as rapidly as today.”
The good news, he says, is that experiments in Australia and round the world have shown it is possible to curb overfishing, runoff and pollution, to limit their local impact on corals.
“Our latest studies have shown corals have a great capacity to bounce back if you take these pressures off them. This means we still have a window of opportunity to act. But we need to act immediately.”
Pandolfi said the action required is threefold:
- Aggressively reduce CO2 emissions;
- Reduce overfishing, pollution and coral habitat destruction; and,
- Implement sound management to improve overall reef health.
Pandolfi this week will present his team’s latest research to the International Coral Reef Symposium. This work aims to disentangle the impact of local effects (like runoff and rainfall) from global effects (like warming and ocean acidification) on the coral’s ability to calcify (or grow) by studying rates of calcification in the columnar coral Goniopora over the past 1000 years.
“We’ve observed widely different effects in some corals, for example when calcification of Porites corals declined by 14 per cent on Australia’s Great Barrier Reef, it increased by 24 per cent on Western Australian reefs. This has got to be down to local effects, as both corals are experiencing some of the same global impacts.”
Managing corals so they thrive, as in the case of Western Australia, may hold the secret of saving the world’s coral reefs in a time that might otherwise bring near-extinction.