CRI听力:Coral Reefs Disease

It's a breakthrough for marine scientists trying to unlock the mystery of what is killing more and more coral reefs in the world's oceans.

There are many factors for the recent worldwide decline of coral reefs - human interference being just one of them - but scientists in Queensland are concerned there has been an increase in coral diseases, creating an urgent need for a deeper understanding of them.

The detection of diseases used to be done with lengthy observation, often taking up to 12 months. During that time, infections and diseases would continue to destroy coral reefs which were previously undisturbed.

Dr David Bourne is Research Scientist at the Australian Institute of Marine Science.

"Trying to diagnose a disease has been very difficult because corals only display a few sick symptoms or signs that they're actually sick."

The difficulty was partly due to the complicated genetic make-up of coral, which is part plant and part animal. But by using a genetic fingerprinting technique, researchers claim to have cut the diagnosis time to just two weeks.

The new method is called quantitative-PCR or qPCR and is commonly used in human medical research or forensics.

Now it is being used by marine scientists to detect the presence of microbes - bacteria, viruses and fungi - that are responsible for causing coral diseases.

Bourne says it is vital to know exactly which toxic organism is the culprit, so they can create an accurate diagnosis and plan counter-measures to manage or reduce its destructive impact.

"What we need to do is actually have a rapid and a robust way to go out there in the field and quickly show that there's something causing that disease and try and identify what is causing it."

qPCR technology detects and quantifies a specific DNA molecule in a sample of diseased coral and can detect pathogens, or infectious agents, at very low levels.

Researchers say they only need a couple of bacteria strains in a cup of seawater. Once scientists have determined the cause of disease, treatment can follow. Bourne says:

"If we know what causes the disease then we've got management options and we know we can look at what is transmitting the disease, in terms of if it's humans or if it's actually something in the marine environment."

Marine scientists hope the new methodology will help to reduce the impact of disease on the world's threatened coral reefs.

And the benefits will extend to countless other forms of marine life that depend on healthy coral for survival.

For CRI, I am Li Dong.