Extinct volcanoes caused tsunamis

SARAH-JANE O'CONNOR
Last updated 12:22 04/07/2014

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Press reporter Sarah-Jane O'Connor looks back at some of the main findings of Kiwi scientists and their compatriots around the world over the past seven days.

1. Squashed undersea volcanoes caused tsunamis

Historic New Zealand tsunamis may have finally been explained, and extinct undersea volcanoes appear to be the culprits.

Geologists identified "tsunami earthquakes" about 35 years ago - earthquakes that do not produce massive shaking but cause larger- than-expected tsunamis.

In March and May 1947 residents in Poverty Bay and Tolaga Bay respectively experienced earthquakes of magnitude 5.9 and 5.6, followed by tsunamis 10 and 6 metres high.

Both areas were sparsely populated at the time and no lives were lost.

Researchers from Imperial College London and New Zealand's GNS Science found two extinct volcanoes off the coast of Poverty Bay and Tolaga Bay that had been "squashed" beneath the Earth's crust. They suggested the volcanoes provided a "sticking point" for moving tectonic plates which allowed energy to build up until it was released in 1947 - causing the two tsunamis.

2. Fish hearts in heat

Auckland University researchers have helped unravel why fish are at risk of heart failure as temperatures rise. Ectothermic animals like fish have body temperatures driven by their surroundings. Tony Hickey and Fathima Iftika compared how three species of wrasse from different environments coped in warmer water. The power-producing mitochondria in the fish's hearts began to fail before the fish experienced full heart failure. The researchers warned that a warming climate could mean increased rates of heart failure in fish, particularly in those from the tropics.

3. No bigfoot DNA

Scientists from Britain have poured cold water on stories of mysterious species such as yeti and bigfoot. They have undertaken the first systematic DNA survey of "cryptozoological species" and found no evidence for the mythical beasts. They surveyed hair samples purported to be from the shy species, but of the 30 samples where DNA was recovered all were attributed to known species.

Of 18 North American samples supposedly from bigfoot, the majority were from bears, canines or cows. Two Himalayan "yeti" samples most closely matched an extinct polar bear.

4. Malarial body odour

The pathogen causing malaria appears to be able to drive more mosquitoes to bite an infected host.

Malaria is caused by a protozoan parasite and is transmitted between hosts by mosquitoes. Once inside a host, the pathogen must still be moved around by mosquitoes to infect further hosts and continue the life-cycle.

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Scientists have shown that mice infected with malaria released a different odour to non-infected mice which made them more attractive to mosquitoes. The effect was strongest when the parasite was in the midst of its reproductive phase, when reproductive cells would be picked up by mosquitoes.

5. Wasp protects nest with dead ants

A newly-found species of spider wasp, named the "bone-house wasp", may use chemical signals from dead ants to protect its nest.

Cavity-nesting wasps lay eggs in brood cells and besides providing food and protection, they then abandon their offspring to fend for themselves. In a study to better understand how these wasps protect their young, researchers from Germany and China collected hundreds of nests from 18 different wasp species in southeast China.

One of those species was the bone-house wasp which lined its nest with dead ants.

The nests appeared to be less vulnerable to parasitism, which the researchers suggested could be due to chemicals emitted from the dead ants.

- The Press

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