Monday, July 11, 2011
Tiny snails survive digestion by birds
July 11, 2011 By Ella Davies
Snails are able to survive intact after being eaten by birds, according to scientists.
Japanese white-eyes on the island of Hahajima, Japan feast on tiny land snails.
Researchers found that 15% of the snails eaten survived digestion and were found alive in the birds' droppings.
This evidence suggests that bird predation could be a key factor in how snail populations spread.
It is well known that plant seeds are dispersed by birds that eat fruit.
But in findings published in the Journal of Biogeography, researchers from Tohoku University, Japan investigated whether invertebrates could also spread in this way.
Previous research has shown that pond snails can survive being eaten by fish but the same was not known for land snails.
Studies of the diets of birds on the island of Hahajima identified the Japanese white-eye's preference for the tiny land snail Tornatellides boeningi.
In the lab scientists fed the birds with the snails to find out whether any survived the digestive process. "We were surprised that a high rate, about 15 percent, of snails were still alive after passing through the gut of [the] birds," explained researcher Shinichiro Wada.
They also studied the genetic differences of T. boeningi populations found across the island and discovered considerable variation.
Rather than only mating with nearby snails, these results suggested that different populations made contact despite their geographical isolation.
"Biogeography of wingless terrestrial invertebrates, in particular snails, is often faced with mysterious long distance dispersal patterns that can only be explained by hand waving arguments involving birds' feet or guts or cyclones," said Mr Wada.
"This is the first study showing that birds can indeed transport a substantial [number of] micro land snails in their gut alive." One snail in particular identified how numerous snails could travel over distances via bird droppings.
"One of the snails fed to the bird gave birth to juveniles just after passing through the gut," Mr Wada told the BBC.
The main factor allowing the snails to survive being eaten is their small size, according to the scientists.
At an average of 2.5mm the micro snails fared much better than larger species in previous studies whose shells were severely damaged when eaten by birds.
Mr Wada and his colleagues said further study is required to find out whether the tiny snails have other adaptations that allow them to survive.
Hahajima lies 1000km south of Tokyo in the Bonin Islands archipelago, known as the Ogasawara Group in Japan.
The islands were recently added to the UNESCO World Heritage List "for the wealth of their ecosystems which reflect a wide range of evolutionary processes".
From: bbc.co.uk/nature
Info is free, spread it!
Snails are able to survive intact after being eaten by birds, according to scientists.
Japanese white-eyes on the island of Hahajima, Japan feast on tiny land snails.
Researchers found that 15% of the snails eaten survived digestion and were found alive in the birds' droppings.
This evidence suggests that bird predation could be a key factor in how snail populations spread.
It is well known that plant seeds are dispersed by birds that eat fruit.
But in findings published in the Journal of Biogeography, researchers from Tohoku University, Japan investigated whether invertebrates could also spread in this way.
Previous research has shown that pond snails can survive being eaten by fish but the same was not known for land snails.
Studies of the diets of birds on the island of Hahajima identified the Japanese white-eye's preference for the tiny land snail Tornatellides boeningi.
In the lab scientists fed the birds with the snails to find out whether any survived the digestive process. "We were surprised that a high rate, about 15 percent, of snails were still alive after passing through the gut of [the] birds," explained researcher Shinichiro Wada.
They also studied the genetic differences of T. boeningi populations found across the island and discovered considerable variation.
Rather than only mating with nearby snails, these results suggested that different populations made contact despite their geographical isolation."Biogeography of wingless terrestrial invertebrates, in particular snails, is often faced with mysterious long distance dispersal patterns that can only be explained by hand waving arguments involving birds' feet or guts or cyclones," said Mr Wada.
"This is the first study showing that birds can indeed transport a substantial [number of] micro land snails in their gut alive." One snail in particular identified how numerous snails could travel over distances via bird droppings.
"One of the snails fed to the bird gave birth to juveniles just after passing through the gut," Mr Wada told the BBC.
The main factor allowing the snails to survive being eaten is their small size, according to the scientists.
At an average of 2.5mm the micro snails fared much better than larger species in previous studies whose shells were severely damaged when eaten by birds.
Mr Wada and his colleagues said further study is required to find out whether the tiny snails have other adaptations that allow them to survive.
Hahajima lies 1000km south of Tokyo in the Bonin Islands archipelago, known as the Ogasawara Group in Japan.
The islands were recently added to the UNESCO World Heritage List "for the wealth of their ecosystems which reflect a wide range of evolutionary processes".
From: bbc.co.uk/nature
Info is free, spread it!
Lightning Kills Seven In Northern Pakistan
BATTAGRAM, PAKISTAN (BNO NEWS) — At least seven people were killed on Saturday when a lightning strike caused rocks to slide down a hill in northern Pakistan, destroying several homes, local media reported on Sunday.
The Express Tribune newspaper reported in its Sunday edition that the incident happened in a village about 25 kilometers (15.5 miles) east of Battagram, a district in the Hazara region of Khyber Pakhtunkhwa province. It happened on Saturday evening when rains and thunderstorms moved through the area.
According to the newspaper report, lightning struck a small hill in the village near union council Shamlai, causing water and rocks to slide down the hill, destroying several houses. “After the lightning it was like lava gushing out of the hillock,” resident Naeem Rehman told The Express Tribune.
The Express Tribune newspaper reported in its Sunday edition that the incident happened in a village about 25 kilometers (15.5 miles) east of Battagram, a district in the Hazara region of Khyber Pakhtunkhwa province. It happened on Saturday evening when rains and thunderstorms moved through the area.
According to the newspaper report, lightning struck a small hill in the village near union council Shamlai, causing water and rocks to slide down the hill, destroying several houses. “After the lightning it was like lava gushing out of the hillock,” resident Naeem Rehman told The Express Tribune.
Eight houses were completely destroyed by the slide while dozens more were damaged. Four bodies had been recovered as of Sunday while three others were presumed to have been killed. Those killed were two women and five children, the paper said, adding that 17 others were injured.
Late last month, 18 children were killed and 36 others were injured when lightning struck a primary school in the Kiryadongo district of Uganda. Lightning also struck other buildings throughout Uganda last month, killing more than 40 people combined. According to a 2008 study by researchers Holle and Lopez for Finnish company Vaisala, lightning strikes each year kill an estimated 24,000 people and injure more than 240,000 others.
From: www.irishweatheronline.com
Info is free, spread it!
From: www.irishweatheronline.com
Info is free, spread it!
A Lost World? Atlantis-Like Landscape Discovered
By Wynne Parry LiveScience.com
Buried deep beneath the sediment of the North Atlantic Ocean lies an ancient, lost landscape with furrows cut by rivers and peaks that once belonged to mountains. Geologists recently discovered this roughly 56-million-year-old landscape using data gathered for oil companies."It looks for all the world like a map of a bit of a country onshore," said Nicky White, the senior researcher. "It is like an ancient fossil landscape preserved 2 kilometers (1.2 miles) beneath the seabed."
So far, the data have revealed a landscape about 3,861 square miles (10,000 square km) west of the Orkney-Shetland Islands that stretched above sea level by almost as much as 0.6 miles (1 km). White and colleagues suspect it is part of a larger region that merged with what is now Scotland and may have extended toward Norway in a hot, prehuman world.
History beneath the seafloor
The discovery emerged from data collected by a seismic contracting company using an advanced echo-sounding technique. High pressured air is released from metal cylinders, producing sound waves that travel to the ocean floor and beneath it, through layers of sediment. Every time these sound waves encounter a change in the material through which they are traveling, say, from mudstone to sandstone, an echo bounces back. Microphones trailing behind the ship on cables record these echoes, and the information they contain can be used to construct three-dimensional images of the sedimentary rock below, explained White, a geologist at the University of Cambridge in Britain.
The team, led by Ross Hartley, a graduate student at the University of Cambridge, found a wrinkly layer 1.2 miles (2 km) beneath the seafloor — evidence of the buried landscape, reminiscent of the mythical lost Atlantis.
The researchers traced eight major rivers, and core samples, taken from the rock beneath the ocean floor, revealed pollen and coal, evidence of land-dwelling life. But above and below these deposits, they found evidence of a marine environment, including tiny fossils, indicating the land rose above the sea and then subsided — "like a terrestrial sandwich with marine bread," White said.
The burning scientific question, according to White, is what made this landscape rise up, then subside within 2.5 million years? "From a geological perspective, that is a very short period of time," he said.
The giant hot ripple
He and colleagues have a theory pointing to an upwelling of material through the Earth's mantle beneath the North Atlantic Ocean called the Icelandic Plume. (The plume is centered under Iceland.)
The plume works like a pipe carrying hot magma from deep within the Earth to right below the surface, where it spreads out like a giant mushroom, according to White. Sometimes the material is unusually hot, and it spreads out in a giant hot ripple.
The researchers believe that such a giant hot ripple pushed the lost landscape above the North Atlantic, then as the ripple passed, the land fell back beneath the ocean.
This theory is supported by other new research showing that the chemical composition of rocks in the V-shaped ridges on the ocean floor around Iceland contains a record of hot magma surges like this one. Although this study, led by Heather Poore, also one of White's students, looked back only about 30 million years, White said he is hopeful ongoing research will pinpoint an older ridge that recorded this particular hot ripple.
Because similar processes have occurred elsewhere on the planet, there are likely many other lost landscapes like this one. Since this study was completed, the researchers have found two more recent, but less spectacular, submerged landscapes above the first one, White said.
Both studies appear today (July 10) in the journal Nature Geoscience.Follow on Twitter @Wynne_Parry & @livescience.
From: lost-world-atlantis-landscape-discovered
Info is free, spread it!
He and colleagues have a theory pointing to an upwelling of material through the Earth's mantle beneath the North Atlantic Ocean called the Icelandic Plume. (The plume is centered under Iceland.)
The plume works like a pipe carrying hot magma from deep within the Earth to right below the surface, where it spreads out like a giant mushroom, according to White. Sometimes the material is unusually hot, and it spreads out in a giant hot ripple.
The researchers believe that such a giant hot ripple pushed the lost landscape above the North Atlantic, then as the ripple passed, the land fell back beneath the ocean.
This theory is supported by other new research showing that the chemical composition of rocks in the V-shaped ridges on the ocean floor around Iceland contains a record of hot magma surges like this one. Although this study, led by Heather Poore, also one of White's students, looked back only about 30 million years, White said he is hopeful ongoing research will pinpoint an older ridge that recorded this particular hot ripple.
Because similar processes have occurred elsewhere on the planet, there are likely many other lost landscapes like this one. Since this study was completed, the researchers have found two more recent, but less spectacular, submerged landscapes above the first one, White said.
Both studies appear today (July 10) in the journal Nature Geoscience.Follow on Twitter @Wynne_Parry & @livescience.
From: lost-world-atlantis-landscape-discovered
Info is free, spread it!
Certain earthquakes have a negative magnitude, is this an error?
Certain earthquakes have a negative magnitude, is this an error?
No, it is not an error. As magnitude calculations are based on a logarithmic scale, a ten-fold drop in amplitude decreases the magnitude by 1. Let us assume that on a seismogram: an amplitude of 20 millimetres corresponds to a magnitude 2 earthquake. 10 times less (2 millimetres) corresponds to a magnitude of 1; 100 times less (0.2 millimetres) corresponds to magnitude 0; 1000 times less (0.02 millimetres) corresponds to magnitude -1. Naturally, a negative magnitude is found only for very small events, which are not felt by humans.
From: earthquakescanada.nrcan.gc.ca/negative_magnitude
Info is free, spread it!
No, it is not an error. As magnitude calculations are based on a logarithmic scale, a ten-fold drop in amplitude decreases the magnitude by 1. Let us assume that on a seismogram: an amplitude of 20 millimetres corresponds to a magnitude 2 earthquake. 10 times less (2 millimetres) corresponds to a magnitude of 1; 100 times less (0.2 millimetres) corresponds to magnitude 0; 1000 times less (0.02 millimetres) corresponds to magnitude -1. Naturally, a negative magnitude is found only for very small events, which are not felt by humans.
From: earthquakescanada.nrcan.gc.ca/negative_magnitude
Info is free, spread it!
The underground plume that feeds the world's largest super-volcano is even BIGGER than scientists thought
Last updated at 6:45 PM on 11th April 2011
The gigantic underground plume of hot and partly molten rock that feeds the world's largest super-volcano is even bigger than previously thought, according to a new study.Scientists made the first large-scale picture of the electrical conductivity in the Yellowstone National Park plume and discovered that it appears larger than in earlier images made with earthquake waves.
Researcher Professor Robert Smith, from the University of Utah, said: 'It's a totally new and different way of imaging and looking at the volcanic roots of Yellowstone.'
The first large-scale picture of the electrical conductivity in the Yellowstone National Park plume, showing the volcanic plume of partly molten rock that feeds the super-volcano. Yellow and red indicate higher conductivity, while green and blue indicate lower conductivity
In a December 2009 study, Professor Smith used seismic waves from earthquakes to make the most detailed seismic images yet of the 'hotspot' plumbing that feeds the Yellowstone volcano.
Seismic waves move faster through cold rock and slower through hot rock. Measurements of seismic-wave speeds were used to make a three-dimensional picture, quite like X-rays are combined to make a medical CT scan.
The 2009 images showed the plume of hot and molten rock dips downward from Yellowstone at an angle of 60 degrees and extends 150 miles west / north-west to a point at least 410 miles under the Montana-Idaho border – as far as seismic imaging could 'see'.
In the new study, images of the Yellowstone plume's electrical conductivity - generated by molten silicate rocks and hot briny water mixed in partly molten rock - showed the conductive part of the plume dipping more gently, at an angle of perhaps 40 degrees to the west, and extending perhaps 400miles from east to west.
Professor Smith said the geoelectric and seismic images of the Yellowstone plume look different because 'we are imaging slightly different things'.
Seismic images highlight materials such as molten or partly molten rock that slow seismic waves, while the geoelectric image is sensitive to briny fluids that conduct electricity.
The study's co-author Professor Michael Zhdanov said: 'The plume is very conductive compared with the rock around it. It's close to seawater in conductivity.'
The lesser tilt of the geoelectric plume image raises the possibility that the seismically imaged plume, shaped somewhat like a tilted tornado, may be enveloped by a broader, underground sheath of partly molten rock and liquids, the researcher said.
Enlarge 
Yellowstone National Park straddles Wyoming, Montana and Idaho. Its caldera has erupted three times in the last 2.1million years
'It's a bigger size in the geoelectric picture,' said Professor Smith. 'We can infer there are more fluids [than shown by seismic images].'
Despite the differences, he said, 'this body that conducts electricity is in about the same location with similar geometry as the seismically imaged Yellowstone plume'.
Professor Zhdanov said that last year, other researchers presented preliminary findings at a meeting comparing electrical and seismic features under the Yellowstone area, but only to shallow depths and over a smaller area.
The researchers used data collected by EarthScope to study the structure and evolution of North America. Using the data to image the Yellowstone plume was a computing challenge because so much data was involved.
The data were collected by 115 stations in Wyoming, Montana and Idaho – the three states straddled by Yellowstone National Park. The stations included electric and magnetic field sensors.
In a supercomputer, a simulation predicts expected electric and magnetic measurements at the surface based on known underground structures. That allows the real surface measurements to be 'inverted' to make an image of underground structure.
Professor Zhdanov said it took about 18 hours of supercomputer time to do all the calculations needed to produce the geoelectric plume picture.
To create the geoelectric image of Yellowstone's plume required two million pixels, or picture elements.
However, the new study said nothing about the chances of another cataclysmic caldera eruption at Yellowstone, which has produced three such catastrophes in the past two million years.
Almost 17 million years ago, the plume of hot and partly molten rock known as the Yellowstone hotspot first erupted near what is now the Oregon-Idaho-Nevada border.
As North America drifted slowly south-west over the hotspot, there were more than 140 gargantuan caldera eruptions – the largest kind of eruption known on Earth – along a north-east trending path that is now Idaho's Snake River Plain.
The hotspot finally reached Yellowstone about two million years ago, yielding three huge caldera eruptions about two million, 1.3million and 642,000 years ago.
Two of the eruptions blanketed half of North America with volcanic ash, producing 2,500 times and 1,000 times more ash, respectively, than the 1980 eruption of Mount St. Helens in Washington state.
Smaller eruptions occurred at Yellowstone in between the big blasts and as recently as 70,000 years ago.
The new University of Utah study has been accepted for publication in Geophysical Research Letters, which plans to publish it within the next few weeks.
From: April 11, 2011 www.dailymail.co.uk/sciencetechInfo is free, spread it!
Subscribe to:
Posts (Atom)