Ocean bones are crumbling
Burnaby scientists are shocked at the rate of climate change impact
Jennifer Moreau, Burnaby Now in Canada.com, Saturday, June 13, 2009
Beneath the blue Caribbean skies lie vast stretches of bones crumbling on the ocean floor. That is what's metaphorically happening to the Caribbean coral reefs. It's as if someone has become sick and died, and now their bones are turning into dust - but much faster than expected. And no one noticed just how fast until a five-member team of scientists, three with links to Burnaby's Simon Fraser University, stepped back and took a look at the bigger picture.
"We were shocked at the scale of the results," says Nick Dulvy, an SFU biologist who worked on the research project. "But we were also shocked that it had gone unnoticed by scientists for a decade or so."
Coral is basically a skin of tissue that lives on top of a skeleton built by the coral, Dulvy explains. The coral's survival depends on algae that live in the tissue. It's a symbiotic relationship: the coral shelters the algae from predators, and the algae feed the corals so they can grow larger. Algae are also what give corals the intense colours they are famous for.
View Larger ImageCrumbling ocean: Lorenzo Alvarez-Filip on a diving expedition. He was lead researcher in a study that involved two other SFU biologists and two international researchers. It was already known that coral reefs in the Caribbean are dying, but this study discovered the dead reefs are collapsing much more quickly than expected.
But the fact that Caribbean coral reefs are dying is nothing new, Dulvy points out. The first plague hit in the '80s; white and black band disease spread, killing about 95 per cent of the complex staghorn and elkhorn types, the antler-shaped corals that provide hiding for fish. To make matters worse, sea urchins were eating the corals up to 1985, until many of them also died of disease.
The final nail in the coral coffin was an El Ni?o event in 1998 that brought on a global rise in sea temperatures. This increased stress on marine ecosystems, allowing previously hidden diseases to emerge in corals that used to be more resilient, Dulvy says.
"With the advent of climate change, they're spreading like wildfire," he says.
The increasing temperatures also bleach the coral, as they lose their coloured, symbiotic algae.
"We don't know whether they are pushed out or whether they chose to leave," Dulvy says of the algae - this is one of the biggest questions in coral research. "The net effect is once they leave, the corals die soon after."
All it takes is a one-degree rise in temperature for 10 weeks to kill everything.
The corals' surface skin has been dying for the last four decades, at a rate twice as fast as the deforestation of the Amazon - 80 per cent of Caribbean coral reefs are now dead.
But what the team discovered is the remaining complex skeletons have now flattened.
Rather than a typical diving expedition, this group of researchers analyzed other people's data. They looked at 500 surveys covering 200 reefs - and what they found was alarming.
"We thought bleached corals' dead skeletons continue to shelter reef inhabitants and shield coastlines from storms and hurricanes. Our team has shown that the dead skeletons are collapsing as fast as the reefs are dying," said Lorenzo Alvarez-Filip, the team's lead researcher.
How fast? Scientists assumed the bleached out skeletons would last about 10 to 15 years - they are collapsing in just one year, and it's been happening since 1998.
"(It's) an entirely new discovery," Dulvy says. "There are probably 600 or 700 coral reef researchers working in the Caribbean, and nobody spotted this phenomena until Lorenzo sat and thought about it for a while."
Scientists were studying their own patch of reef, like gardeners working their own little plot of land.
"We were the first people in the world ... to get together everybody's understanding of how their patches have changed," Dulvy says. "The answer was sitting in our libraries all along. That's the surprising thing."
Dulvy says people should be concerned because the corals are like a canary in the coal mine - a harbinger of what climate change can bring.
"It's telling us that climate change has the power, or has already had the power, to devastate one of the most species-diverse ecosystems on the earth," he says.
Canadians can help by reducing their carbon emissions, Dulvy says.
"I guess we all have to bite the bullet at some point and think hard about our lifestyles."
Alvarez-Filip is a doctoral student of Dulvy and fellow SFU biology professor Isabelle Cote, who also formed part of the team. They were joined by two other international researchers: Jennifer Gill and Andrew Watkinson of the University of East Anglia in the U.K. Their findings on the flattening coral reefs were published June 10 online in Proceedings of the Royal Society of London-B, a biological research journal. Cote and Dulvy were scheduled to receive an award from the Zoological Society of London June 16 for their conservation work.
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