Wild Things

The weird and wonderful in the natural world

Sarah Zielinski

Wild Things

Wild Things

Coral competitor becomes ally in fight against starfish

crown-of-thorns starfish

An outbreak of crown-of-thorns starfish (one shown) can devastate a reef. But algae, a coral competitor, may protect coral from the predatory starfish, a new study finds.

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Coral and algae don’t get along. On reefs, algae compete with coral, reducing coral growth and survival. Scientists suspect that the algae may also promote harmful bacteria or coral-eating species, causing further coral damage.

But coral have an even bigger worry: the crown-of-thorns starfish. These are large (up to about a third of a meter) seastars covered in venomous spikes that feed on coral polyps. Outbreaks of the starfish, which are native to the Indo-Pacific, can damage large sections of reef and even kill an entire coral colony.

So the combination of starfish and algae sounds bad for coral — but it may not be, a new study finds. The algae might protect the coral from the predatory seastars, Cody Clements and Mark Hay of Georgia Institute of Technology in Atlanta conclude August 26 in the Proceedings of the Royal Society B.

Clements and Hay performed a series of experiments in Fiji on Montipora coral, a favorite prey of crown-of-thorns starfish. They photographed reefs that had been attacked and those that hadn’t, quantifying algae cover on both. They planted tiny coral surrounded by various amounts of Sargassum algae to see how coral growth was affected. And they set up feeding trials for the starfish to see whether they would attack coral when algae was present.

The more algae that was around, the more coral growth declined, the researchers found. But the Sargassum seemed to have a protective effect when the starfish was present: There was less predation on reefs that had more algae. Attacked colonies had about 8 percent algal cover compared with 55 percent on reefs that were untouched. And in the feeding experiments, corals without any algae were always attacked while those with higher amounts of Sargassum were rarely consumed.

The algae could even force the seastars to change their feeding preferences. Crown-of-thorns prefer Montipora coral over Porites coral. But if the Monitpora is surrounded by algae, the starfish settle for the less-preferable Porites meal, the researchers found.

What is it about the algae that turns the starfish off? It is probably the physical structure of the Sargassum, the researchers suggest. When they put fake plastic Sargassum around the coral, seastars were much less likely to attack, similar to what happened with the real algae.

Animals,, Plants

Could the dinos of ‘Jurassic World’ become invasive?

By Sarah Zielinski 2:45pm, June 12, 2015
Even if they escaped their island home, the giant reptiles of ‘Jurassic World’ probably wouldn’t survive on the mainland. But the movie’s plants are another story.

Chimps get buzzed on fermented tree sap

By Sarah Zielinski 7:05pm, June 9, 2015
Scientists have documented the first case of chimpanzees drinking ethanol in the wild.

Camera traps provide treasure trove of African animal pics

By Sarah Zielinski 9:00am, June 9, 2015
Scientists set up hundreds of cameras across Serengeti National Park to capture images of predators and their prey.
Animals,, Conservation

‘Virgin births’ won’t save endangered sawfish

By Sarah Zielinski 1:40pm, June 5, 2015
Sawfish are the first wild vertebrates found to reproduce via parthenogenesis.

African herbivores share space but not diet

By Sarah Zielinski 3:00pm, June 3, 2015
Large herbivorous mammals on the plains of Kenya have distinctive diets, a new study finds.
Animals,, History of Science,, Oceans

Wealth of cephalopod research lost in a 19th century shipwreck

By Sarah Zielinski 1:39pm, May 29, 2015
Nineteenth-century scientist Jeanne Villepreux-Power sent her research papers and equipment on a ship that sank off the coast of France, submerging years’ worth of observations on cephalopods.
Animals,, Conservation

Wild dogs cause problems for people in Nepal

By Sarah Zielinski 11:20am, May 27, 2015
The endangered dhole has a reputation for killing livestock, but its taste for blue sheep could also be an issue, a new study finds.

These birds provide their own drum beat

By Sarah Zielinski 2:43pm, May 22, 2015
Male Java sparrows use bill clicks in their songs, which they learn from their dads.
Animals,, Climate

Rising temperatures may cause problems for cold-blooded critters

By Sarah Zielinski 3:00pm, May 20, 2015
Ectotherms cannot easily handle extreme temperatures, a new study finds.
Animals,, Plants

A summer challenge: Observe nature

By Sarah Zielinski 12:08pm, May 15, 2015
Opportunities for observing nature are plentiful, no matter where you live.
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