Tag Archives: Crown of Thorns Starfish

Coral Reef news round-up

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“Reef guide to benefit research” (Sydney Morning Herald, 26/11/08)

‘I mean we’re not going to have reefs for much longer but we can at least have them a bit longer.” Pat Hutchings, a 40-year veteran of coral reef research, is not optimistic for the long-term future of the Great Barrier Reef but she is determined to do everything within her power to help its survival.

Hutchings has been poking around reefs since her student days, before scuba diving existed outside the armed forces. “When I went to learn in the mid to late ’60s, we had to make our own wetsuits – you couldn’t buy them,” she says. “There were a few naval divers but it wasn’t available to students. Prior to that people swam around with a box with glass on the bottom to look through.” (Read More)

“Ending the reef madness”
(The Australian, 26/11/08)

OVE Hoegh-Guldberg is blunt about the gloomy prospects for the Great Barrier Reef.

“We have no time to lose,” said the director of the University of Queensland’s Centre for Marine Studies.

“We are three decades away from having a reef with no coral and less than half the species we have today. It is crunch time.”

Speaking on the eve of the publication of a unique book, The Great Barrier Reef, the first comprehensive field guide to the world’s largest continous reef, he stressed the imperative to act. “Part of the mission for us as scientists is to pass on the urgency and excitement about these issues.” (Read More)

“Climate change, starfish hit Fiji Reefs: Study”
(ABC News, 24/11/08)

Climate change and a starfish outbreak have shrunk coral reefs near Fiji, forcing locals to change their lifestyle.

A new study, published in Global Change Biology, has found that from 2000-2006 the size of coral reefs around Fiji’s remote Lau Islands contracted by about 50 per cent.

Dr Nick Graham from James Cook University, who took part in the study, says fishing and habitat disturbance are having a big impact.

“The area was disturbed by a crown of thorns starfish outbreak in about 2000 and then, the subsequent year, there was also a coral bleaching event associated with climate change,” Mr Graham said.

“We were pretty shocked at just how severe the impact was.” (Read More)

“Oceans acidifying faster than predicted, threatening shellfish”
(Bloomberg, 25/11/08)

Oceans are acidifying 10 times faster than predicted, threatening heightened damage to coral reefs and shellfish, University of Chicago scientists said.

Researchers took more than 24,000 pH measurements over eight years and found the rate at which the ocean is becoming more acidic correlates with the atmospheric concentration of carbon dioxide, or CO2, the university said in a statement. When CO2, which helps cause global warming, dissolves in water, it forms carbonic acid.

“The acidity increased more than 10 times faster than had been predicted by climate change models and other studies,” University of Chicago ecology and evolution professor Timothy Wooton said in the statement. “This increase will have a severe impact on marine food webs and suggests that ocean acidification may be a more urgent issue than previously thought.” (Read More)

A threat to coral reefs multiplied? Four species of crown of thorns starfish

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Crown of thorns starfish (COTS – Acanthaster planci) are notorious throughout the Indo-Pacific region. COTS are voracious coralivores, and in outbreak proportions can eat vast areas of reef by exuding their stomachs and digesting coral polyps (read more). Having been diving in oceans around the world over the past few decades, i’ve often pondered the differences in colourations of COTS between reef regions, and whether they represented a single species. A recent paper published in Biology Letters by Catherine Vogler from Göttingen University and colleagues at the Smithsonian and University of California confirms that COTS aren’t a single taxonomic entity, and in fact represent a ‘species complex’ of upto four seperate species.

Different appearances of the Crown of Thorns starfish across locations, clockwise from Top Left: Madagascar (Image credit: Mila Zinkova), Thailand (Image credit: Jon Hanson) Okinawa, Japan (Image credit: Gary Hughes), Fiji (Image credit: Matt Wright)

Using a genetic approach, the researchers analysed DNA from over 237 starfish collected from reefs around the world. Their results strongly suggest that their are in fact four species of COTS, located in the Pacific Ocean, Red Sea, Southern Indian Ocean and Northern Indian Ocean).

Geographical distribution of the different species of crown of thorns (each colour represents a different species where sampled, piecharts indicte the frequency of each species per location)

It’s fascinating to think that the divergence of these species occured between the Pliocene (3.65 million years ago) and early Pliestocene (1.95 million years ago). More importantly though, this discovery may have fairly interesting implications for conservation biology. The researchers point out that whilst outbreaks of COTS are well-researched phenomena on the GBR and Indo-Pacific reefs since the early 1960’s, outbreaks in the Indian Ocean and Red Sea are much less severe. It seems that a better understanding of the genetic structure of COTS populations and identifying species boundaries may go a long way to explaining the intensity and magnitude of COTS outbreaks in different regions.

Reference: Vogler et al (2008) A threat to coral reefs multiplied? Four species of crown of thorns starfish. Biology Letters doi:10.1098/rsbl.2008.0454 (Link)