The Australian newspaper published an article this weekend entitled “Great Barrier Reef could adapt to climate change, scientists say”.
THE prediction of a prominent marine biologist that climate change could render the Great Barrier Reef extinct within 30 years has been labelled overly pessimistic for failing to account for the adaptive capabilities of coral reefs.
University of Queensland marine biologist Ove Hoegh-Guldberg said yesterday that sea temperatures were likely to rise 2C over the next three decades, which would undoubtedly kill the reef.
But several of Professor Hoegh-Guldberg’s colleagues have taken issue with his prognosis.
Andrew Baird, principal research fellow at the Australian Research Council’s Centre for Excellence for Coral Reef Studies, said there were “serious knowledge gaps” about the impact rising sea temperatures would have on coral.
“Ove is very dismissive of coral’s ability to adapt, to respond in an evolutionary manner to climate change,” Dr Baird said.
“I believe coral has an underappreciated capacity to evolve. It’s one of the biological laws that, wherever you look, organisms have adapted to radical changes.”
Dr Baird acknowledged that, if left unaddressed, climate change would result in major changes to the Great Barrier Reef.
“There will be sweeping changes in the relative abundance of species,” he said. “There’ll be changes in what species occur where.
“But wholesale destruction of reefs? I think that’s overly pessimistic.”
Dr Baird said the adaptive qualities of coral reefs would mitigate the effects of climate change.
I must say I’m a little amazed that Andrew Baird has come out with such poorly supported statements. In fact, his conclusions seem to depend almost entirely on his personal opinion! The argument that corals are able to magically “adapt” over one or two decades to climate change (even though their generation times are often longer) has come up many times over the years – always, with a complete dearth of evidence to support it.
I wrote to Andrew Baird yesterday, to try and understand if there was something that he knew that I might have missed in the scientific lecture. In response, Andrew sent me a recent article published by Jeff Maynard and himself (Maynard et al 2008).
Unfortunately, the article is an opinion piece (a bit like the newspaper article) that is poorly supported by anything but the most scant evidence (if you could actually call it that) from literature. I have responded to these types of articles before, but frustrated, here we go again:
Maynard et al (2008) state the following as important evidence that corals can adapt to changes in the environment, and therefore that they can adapt to the current very rapid changes in ocean temperature and acidity.
“..geographic variation in bleaching thresholds within species, sometimes over scales <100km, provides circumstantial evidence for ongoing evolution of temperature tolerance between both species and reef”
Let me start by saying that no credible biologist would doubt the role of evolution in the shaping of the physiology and ecology of corals with respect to temperature. Biological populations evolve in response to stress. However, the mere observation of geographic variation in thermal tolerance, does not give any hint about the rates or the length of time that these changes have taken to occur. Importantly, this statement does not equate to evidence that thermal tolerance can evolve in ecological time. The only way that Andrew Baird could convince anyone of this particular somewhat fanciful leap of logic is to present data that show that coral populations can rapidly evolved in the period of years. They can’t, and they haven’t.