Oz - "Spectacular" Recovery From 06 Coral Bleaching - But Good Conditions "Lucky", Scientists Say

[hatrack]

Sections of coral reef in Australia's Great Barrier Reef have made a "spectacular" recovery from a devastating bleaching event three years ago, marine scientists say. In 2006, high sea temperatures caused severe coral bleaching in the Keppell Islands, in the southern part of the reef — the largest coral reef system in the world. The damaged reefs were then covered by a single species of seaweed which threatened to suffocate the coral and cause further loss.

A "lucky combination" of rare circumstances has meant the reef has been able to make a recovery. Abundant corals have reestablished themselves in a single year, say the researchers from the University of Queensland's Centre for Marine Studies and the ARC Centre of Excellence for Coral Reef Studies (CoECRS).

"Three factors were critical," said Dr Guillermo Diaz-Pulido. "The first was exceptionally high regrowth of fragments of surviving coral tissue. The second was an unusual seasonal dieback in the seaweeds, and the third was the presence of a highly competitive coral species, which was able to outgrow the seaweed."

Coral bleaching occurs in higher sea temperatures when the coral lose the symbiotic algae they need to survive. The reefs then lose their colour and become more susceptible to death from starvation or disease. The findings are important as it is extremely rare to see reports of reefs that bounce back from mass coral bleaching or other human impacts in less than a decade or two, the scientists said. The study is published in the online journal PLoS one.

EDIT

http://www.guardian.co.uk/environment/2009/apr/22/coral-barrier-reef-australia

[ben_jenne]

1. I wonder if an "unlucky combination" of rare circumstances

Caused the bleaching in the 1st place? I suppose that wouldn't fit the profile.

[phantom power]

2. In a sense, yes. We sometimes call those circumstances the Industrial Revolution.

[ben_jenne]

3. So is the Industrial Revolution over and that's

what caused the "Lucky Circumstances"?

[phantom power]

4. I think the article describes those circumstances pretty well.

A baseline of surviving coral, a bad year for algae, and competitive coral species.

[gulfcoastliberal]

5. The Aussie's are still trying their best to kill the reef with ag. runoff pollution.

I read a study that linked the population explosion of the crown of thorns to the nutrient soup provided by ag runoff into rivers, which empty into the ocean near the reef.

[Nederland]

6. I wonder what the sample size is?

In other words, do we really know if this was actually a "lucky combination of rare circumstances"? How many times have we witnessed this type of devastating bleaching and been able to record and study the aftermath? Two or three other times, max? Hardly a large enough sample size to start making claims about the commonality of the described circumstances. IMHO I think we cannot possibly have enough information to make these types of conclusions.

It reminds me of what many scientists were saying after the huge fires that burned much of Yellowstone park in 1988. We were told that it would take decades for Yellowstone to recover, and yet the Yellowstone of today is teeming with life. I suspect that we humans do not understand naturals system quite as well as we'd like to think we do.

[depakid]

7. "the presence of a highly competitive coral species"

Sounds like that's an angle that merits further study.

[phantom power]

8. I've been kind of expecting to see some natural selection in action...

as regards coral and other kinds of species. There have been rapid warming events before in the history of corals. They've been around a very very long time.

I expect we will lose most of the reefs before it's over. Future generations will get to observe re-colonization. Assuming anybody is around with enough energy to observe.