Post by L Roebuck on Aug 12, 2006 19:08:21 GMT -5
Going to bat for climate research
By Susanne Rust
Milwaukee Journal Sentinel
(MCT)
MILWAUKEE, Wis. - The much-maligned bat may soon be earning praise from climate scientists, after a discovery that the winged mammals have dropped thousands of years of data in caves throughout the world.
That data is waiting to be mined - but only by researchers willing to scour through millenniums of bat poop.
According to Louis J. Maher Jr., a retired professor of geology and geophysics at the University of Wisconsin-Madison, guano, or bat dung, can be used to examine ancient environments in a manner analogous, or even preferable, to lake sediment or peat.
Unlike those more traditional methods, however, "you have to keep a sense of humor about this type of research," Maher said. "It's one of those things people like to snigger at" - despite the fact these piles can provide valuable information about geographic regions that are not amenable to more traditional paleoclimatic analysis.
Piled high on cave floors, certain large deposits of bat scat have been accumulating for thousands, if not tens of thousands, of years. And in each heap, or cone, valuable records of the insects, pollen and minerals the bats encountered during their nightly forages have been collected, preserved and neatly layered in chronological order, from bottom to top.
In a recent issue of the journal Palaeogeography, Palaeoclimatology, Palaeoecology, Maher described a visit to a bat cave in southern Missouri where he was able to take a core sample from a large pile of guano, then examine the stratigraphically layered pollen, mineral and insect deposits within.
The 28-inch-deep pile he chose - which he said wasn't the deepest in the cave - was carbon-dated by the Lawrence Livermore National Laboratory in California to nearly 3,000 years at its lowest layers.
Using a standard piston sampler - one designed to take lake sediment cores - the sample was removed from its mound and wrapped in plastic foil. According to Maher, it had no noticeable odor, was crumbly and had the color of mahogany.
Maher is not the first researcher to recognize the importance of animal waste as a valuable tool for reconstructing past climate events. According to Gavin Schmidt, a paleoclimatologist at NASA'a Goddard Institute for Space Studies in New York, others have combed through encrusted pack rat urine and feces, primarily in the Southwest, and obtained similarly promising results.
"It sounds reasonable," he said, when asked what he thought of the Maher's methodology. But, he added, he was not a specialist.
Owen Davis, a palynologist - or pollen researcher - at the University of Arizona in Tucson, held a "Feces Through Time" symposium in 2003, where Maher's work was first presented. Davis believes the information gleaned from such accumulations is valuable.
"This is a really fertile area," he said.
For instance, in the arid Mediterranean region, researchers have been combing through cave-preserved hyena dung to analyze pollen on the partially digested and preserved skins of this scavenger's ancient quarry. And in the Mideast, middens of such animals as the dassie rat and hyrax have proved fruitful.
The beauty of Maher's work, though, said Davis, is that unlike pack rat middens or hyena dumps - in which each poop represents a discrete moment in time - one deep guano core can provide a window into a thousand years, or more, of environmental and ecological change.
And in areas where lakes are few, such deposits can contribute to a richer, clearer picture of a region's environmental history.
Pollen samples - whether pulled from lakes, peat or guano - enable investigators to "see" historical ecosystems. The number and percentage of grains can tell a researcher what kinds of plants abounded during a particular period of time. Is the sample heavy with oak, conifer or grass pollen? What other plants can be identified?
Comparing the pollen makeup of the sample with modern ecosystems, the researcher can then identify the environment, and climate, in which the sample was created.
In 1990, Maher was asked by the owner of the Tumbling Creek Cave, a National Natural Landmark near Protem, Mo., to examine the cave's guano cones for pollen content. The cave is said to contain the most diverse population of animals in any cave west of Mississippi River.
Intrigued by the prospect, Maher went for a visit.
His thinking went something like this: Insects pick up pollen by visiting flowers, and many temperate-region bats eat insects. Because pollen grains are difficult to digest, they should pass through the bat, and land on the floor below the roost. If several generations of bats had occupied the cave, those piles should include a stratigraphic record of pollen grains.
He was hoping the guano would serve as a record of insect-pollinated plants. He was wrong.
Instead, he discovered the pollen collected in the guano represented atmospheric pollen - the stuff floating in the air around us.
The difference might sound academic, but to Maher it was important.
It meant that the contents of the guano, which consisted primarily of insect fragments, hair, pollen and mineral matter, reflected atmospheric debris, not the ecological habits of pollinating insects.
Night-flying insects do not normally visit flowers for pollen, Maher said. So the pollen found on their bodies (the primary element in guano) is incidental; they "essentially act as living traps for airborne debris," he wrote in his paper.
He verified this assumption by analyzing dead insects trapped in a yard light at his home, and in the glass cover of a light over the freight dock at Weeks Hall, his office building on the UW campus. The insects were covered with atmospheric pollen.
Bat fur, too, serves as a trap for atmospheric pollen. When the nocturnal critters groom, they ingest the pollen and dust accumulated on their fur during their nightly foray. Both the insects they caught, and the fur they licked, are then excreted into piles on the cave floor, where they are sheltered from wind, rain, light and extremes in temperature.
The amazing thing about all of this, Maher said - and the reason guano cores might work as well as or better than lake sediment cores - is that the pollen in an individual scat contains a record of the atmospheric pollen during a single day. So, as with the hyena and pack rat collections, a discrete moment can be analyzed - offering a snapshot in time. But like a sediment or ice core, the stratigraphical accumulation of these discrete packages also provides a motion picture of time.
Full Article: www.grandforks.com/mld/grandforks/news/nation/15261008.htm
By Susanne Rust
Milwaukee Journal Sentinel
(MCT)
MILWAUKEE, Wis. - The much-maligned bat may soon be earning praise from climate scientists, after a discovery that the winged mammals have dropped thousands of years of data in caves throughout the world.
That data is waiting to be mined - but only by researchers willing to scour through millenniums of bat poop.
According to Louis J. Maher Jr., a retired professor of geology and geophysics at the University of Wisconsin-Madison, guano, or bat dung, can be used to examine ancient environments in a manner analogous, or even preferable, to lake sediment or peat.
Unlike those more traditional methods, however, "you have to keep a sense of humor about this type of research," Maher said. "It's one of those things people like to snigger at" - despite the fact these piles can provide valuable information about geographic regions that are not amenable to more traditional paleoclimatic analysis.
Piled high on cave floors, certain large deposits of bat scat have been accumulating for thousands, if not tens of thousands, of years. And in each heap, or cone, valuable records of the insects, pollen and minerals the bats encountered during their nightly forages have been collected, preserved and neatly layered in chronological order, from bottom to top.
In a recent issue of the journal Palaeogeography, Palaeoclimatology, Palaeoecology, Maher described a visit to a bat cave in southern Missouri where he was able to take a core sample from a large pile of guano, then examine the stratigraphically layered pollen, mineral and insect deposits within.
The 28-inch-deep pile he chose - which he said wasn't the deepest in the cave - was carbon-dated by the Lawrence Livermore National Laboratory in California to nearly 3,000 years at its lowest layers.
Using a standard piston sampler - one designed to take lake sediment cores - the sample was removed from its mound and wrapped in plastic foil. According to Maher, it had no noticeable odor, was crumbly and had the color of mahogany.
Maher is not the first researcher to recognize the importance of animal waste as a valuable tool for reconstructing past climate events. According to Gavin Schmidt, a paleoclimatologist at NASA'a Goddard Institute for Space Studies in New York, others have combed through encrusted pack rat urine and feces, primarily in the Southwest, and obtained similarly promising results.
"It sounds reasonable," he said, when asked what he thought of the Maher's methodology. But, he added, he was not a specialist.
Owen Davis, a palynologist - or pollen researcher - at the University of Arizona in Tucson, held a "Feces Through Time" symposium in 2003, where Maher's work was first presented. Davis believes the information gleaned from such accumulations is valuable.
"This is a really fertile area," he said.
For instance, in the arid Mediterranean region, researchers have been combing through cave-preserved hyena dung to analyze pollen on the partially digested and preserved skins of this scavenger's ancient quarry. And in the Mideast, middens of such animals as the dassie rat and hyrax have proved fruitful.
The beauty of Maher's work, though, said Davis, is that unlike pack rat middens or hyena dumps - in which each poop represents a discrete moment in time - one deep guano core can provide a window into a thousand years, or more, of environmental and ecological change.
And in areas where lakes are few, such deposits can contribute to a richer, clearer picture of a region's environmental history.
Pollen samples - whether pulled from lakes, peat or guano - enable investigators to "see" historical ecosystems. The number and percentage of grains can tell a researcher what kinds of plants abounded during a particular period of time. Is the sample heavy with oak, conifer or grass pollen? What other plants can be identified?
Comparing the pollen makeup of the sample with modern ecosystems, the researcher can then identify the environment, and climate, in which the sample was created.
In 1990, Maher was asked by the owner of the Tumbling Creek Cave, a National Natural Landmark near Protem, Mo., to examine the cave's guano cones for pollen content. The cave is said to contain the most diverse population of animals in any cave west of Mississippi River.
Intrigued by the prospect, Maher went for a visit.
His thinking went something like this: Insects pick up pollen by visiting flowers, and many temperate-region bats eat insects. Because pollen grains are difficult to digest, they should pass through the bat, and land on the floor below the roost. If several generations of bats had occupied the cave, those piles should include a stratigraphic record of pollen grains.
He was hoping the guano would serve as a record of insect-pollinated plants. He was wrong.
Instead, he discovered the pollen collected in the guano represented atmospheric pollen - the stuff floating in the air around us.
The difference might sound academic, but to Maher it was important.
It meant that the contents of the guano, which consisted primarily of insect fragments, hair, pollen and mineral matter, reflected atmospheric debris, not the ecological habits of pollinating insects.
Night-flying insects do not normally visit flowers for pollen, Maher said. So the pollen found on their bodies (the primary element in guano) is incidental; they "essentially act as living traps for airborne debris," he wrote in his paper.
He verified this assumption by analyzing dead insects trapped in a yard light at his home, and in the glass cover of a light over the freight dock at Weeks Hall, his office building on the UW campus. The insects were covered with atmospheric pollen.
Bat fur, too, serves as a trap for atmospheric pollen. When the nocturnal critters groom, they ingest the pollen and dust accumulated on their fur during their nightly foray. Both the insects they caught, and the fur they licked, are then excreted into piles on the cave floor, where they are sheltered from wind, rain, light and extremes in temperature.
The amazing thing about all of this, Maher said - and the reason guano cores might work as well as or better than lake sediment cores - is that the pollen in an individual scat contains a record of the atmospheric pollen during a single day. So, as with the hyena and pack rat collections, a discrete moment can be analyzed - offering a snapshot in time. But like a sediment or ice core, the stratigraphical accumulation of these discrete packages also provides a motion picture of time.
Full Article: www.grandforks.com/mld/grandforks/news/nation/15261008.htm