A recent paper published in the Proceedings of the National Academy of Science suggests that hurricanes may well be the ‘unlikely saviours of coral reefs’ (link to the New Scientist article). In short, researchers from the Caribbean determined that on average, hurricanes will actively cool sea temperatures by 1.5°C for upto 10 days. Since hurricanes occur during the hot summer months, this reduction in sea temperatures acts as a lifeline for thermally stressed and bleached corals within the region.

The authors conclude that “…severe bleaching events can have dramatic, long lasting impacts on the structure and function of coral reefs, and the cooling benefit of a hurricane can have substantial mitigative effects”. Parallels can be drawn between hurricanes in the Caribbean region and cyclone events on the Great Barrier Reef.

Back in the summer of 2006, substantial warming of the oceans on the GBR threatened yet another bleaching event of a magnitude of 1998 and 2002. Fortunately for the reef, the category 5 cyclone Larry produced significant cooling effects across the length of the GBR resulting in minimal coral bleaching – acting as an ‘unlikely savior”. At the time, I was the subject of this diatribe from the ‘journalist’ Andrew Bolt, published in the Herald Sun:

Hoegh-Guldberg, head of Queensland University’s Centre for Marine Studies, has threatened us more often than most. Just three months ago he was at it again, issuing a press release with a grim warning: High temperatures meant “between 30 and 40 per cent of coral on Queensland’s Great Barrier Reef could die within a month”. Just four paragraphs on he upped the ante, warning that the warm seas “may result in greater damage” still—to more than 60 per cent of the reef.

In his infinite wisdom, Bolt goes on to say:

Ask—hey!—Hoegh-Guldberg himself. He’s just back from a trip out to the outer reef and reports that, um, the bleaching, er, has had, well, “quite a minimal impact”, after all. In fact, just 1 per cent was affected. And history tells us even that little bit will recover.

My favourite excerpt:

Note well: I’m certain Hoegh-Guldberg believed this booga booga, based on his understanding of the science.

Well, I guess the last excerpt says it all. Bolt, a self-appointed expert and with half the facts can spin a great story. No doubt about it. We have come to expect that from Bolt.

But I guess there is a big difference between the ramblings of a columnist and what actually happened. What poor old Boltie forgot to tell you is that corals in the southern Great Barrier Reef – around places like the Keppel Islands – experienced coral mortalities of 40% of more. And I suppose this didn’t fit with his story.

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One Response to Hurricanes and coral bleaching

  1. [...] coral sea could potentially dissapate the thermal stress build up that triggers coral bleaching (read more). We will keep posting updates on the 2008/2009 season as the bleaching outlook changes. Tagged [...]

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