SNIPPETS - Effects of droughts written on cave walls of China

Last Updated : 24 August 2015, 18:36 IST
Last Updated : 24 August 2015, 18:36 IST

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Effects of droughts written on cave walls of China

Writings on the walls of a cave in China record the effects of droughts during the last 500 years, researchers have found. The inscriptions are on the walls of Dayu Cave in the Qinling Mountains of central China. They describe the effects of seven droughts between 1520 and 1920.

One inscription, dated 1528, reads, “Drought occurred in the seventh year of the Emperor Jiajing period, Ming dynasty. Gui Jiang and Sishan Jiang came to Da’an town to acknowledge the Dragon Lake inside in Dayu Cave.”

Another, from 1891, reads, “On May 24th, 17th year of the Emperor Guangxu period, Qing dynasty, the local mayor, Huaizong Zhu, led more than 200 people into the cave to get water. A fortuneteller named Zhenrong Ran prayed for rain during the ceremony.”

Records of yore

The cave inscriptions are described in the journal Scientific Reports. Researchers also analysed stalagmites in Dayu Cave, which are formed by dripping water and contain rings that record their growth, as do trees. After analysing the stable isotopes of oxygen, carbon and concentrations of uranium and other elements inside the stalagmites, the researchers found higher oxygen and carbon isotope ratios in years with lower rainfall.
“We now have a direct link between what people experienced at the time and our geochemical reference,” said Sebastian Breitenbach, a climate scientist at the University of Cambridge and one of the paper’s co-authors.

He and his colleagues used the information from the stalagmites to construct a model of precipitation in the region in more recent times. It correlated with a drought in the 1990s and predicted another in the late 2030s.

Sindya N Bhanoo

An unusual octopus gets a thorough lookThe larger Pacific striped octopus is, despite its name, no bigger than a tangerine. And it has long managed to keep a low profile in the coastal waters off the eastern Pacific. Roy Caldwell, a researcher of invertebrate studies at the University of California, Berkeley, and his team obtained 24 of these octopuses from private collectors in Nicaragua and published their research in the journal PLOS One.
The species is indeed unusual. While other octopuses mate by mounting, the larger Pacific striped octopus engages in “beak to beak” mating; the beaks are on the underside of their bodies. Females of the species have also been found to brood over their eggs up to six months, far longer than other species of octopus do. They also appear to be surprisingly social.

The octopuses were placed in groups of eight in large tanks. None of them killed any of their tankmates (octopuses are no strangers to cannibalism), and by all appearances they seemed to get along. The larger Pacific striped octopus also uses a “slow bounce” to hunt. With its body flattened, and dorsal arms reaching forward, the octopus glides with sporadic bursts of hopping movements before it snatches up its prey of choice – usually shrimp.

Ashaki Lloyd

If mosquitoes disappeared, what would happen?
Just imagine. What if the planet were rid of all mosquitoes? Would there be any negative environmental consequences?

Experts say it is impossible to know for sure, because so many varieties of mosquitoes fill so many environmental niches, feeding on and being fed on by such a variety of other creatures, and because many of these interactions have not been studied. But it is only natural that people, pestered by itchy bites and bearing the brunt of mosquito-borne diseases, would hope the answer is no.

Many birds, bats, amphibians, fish, spiders and other insects feed on mosquitoes, but many mosquito-control specialists say they usually do not eat enough mosquitoes to control them, let alone to make the loss of mosquitoes crucial to whether the predators survive. In-depth studies have found that mosquitoes form at most 3 per cent of the voracious purple martin’s diet, according to the American Mosquito Control Association.
A survey of scientists on mosquito eradication, published in 2010 by the journal Nature, concluded by quoting the head of the association, who said that eradication would be a “hiccup” for the environments where mosquitoes are active and that “something better or worse would take over.”

Published 24 August 2015, 17:12 IST

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