December 1, 2012 - Dead Trees, Warm Forests * Hermit Crab's Shell Game * Peruvian Peak Water * The Enemy of my Enemy of my Enemy * Near Earth Objects

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It's happened before, it'll happen again.  From the depths of space, a comet or asteroid will flash through the skies, striking the Earth, and creating a global catastrophe.  Or maybe not.  We are the first life form on Earth with the capacity to prevent at least that particular threat to our existence, and on today's program, we'll find out how.  Plus, we'll find out how hermit crabs play a rough game of musical shells; we'll learn how melting glaciers in Peru could lead to less drinking water, and we'll hear the complicated tale of the wasp that eats the wasp that eats the caterpillar that eats the plant. But first - small beetle, big impact.

 


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Dead Trees, Warm Forests
Pine_Beetle_Damage.jpgPine Beetle damaged forests in BC. Copyright Themightyquill

It is estimated that the mountain pine beetle has spread throughout about 20 percent of forests in British Columbia.  The destructive beetle has been the beneficiary of climate change, as the cold temperatures that once killed if off in winter are no longer occurring.   But a new study, by Dr. Holly Maness, a Post-doctoral scholar in the Earth Sciences Department at the University of California Berkeley, who did her research at the University of Toronto, has found that the pine beetle is so widespread it is actually contributing to climate change now.  Trees sweat in order to cool themselves, just like humans.  But the 170,000 square kilometres of dead and dying trees in B.C. no longer contribute this form of water into the atmosphere.  Instead, the solar energy required to make trees sweat is now heating the surface soil.  On average, the result is an increase in temperature of 1 degree C for the infested area, and as high as 3 to 4 degrees in areas where the concentration of dead trees is highest.
          
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Hermit Crab's Shell Game

hermitcrab.jpgHermit crab, courtesy M. Laidre
Hermit crabs live in the empty shells of other animals - often those of marine snails.  This, for the crab, creates the kind of problem some humans find familiar: real estate envy.  Crabs are always looking for a bigger, better shell, and generally, the best way to get one is to steal one from another hermit crab.  But, of course, when you steal another crab's shell, your shell is empty and available for other hermit crabs to occupy, if it's better than their own.  Dr. Mark Laidre, a research fellow in the Department of Integrative Biology at the University of California, Berkeley, has been studying a species of hermit crab in whom this behaviour has evolved into a crab "conga line."  When two crabs fight, a line-up appears behind them, as other crabs jockey to switch into new and better homes.

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Peruvian Peak Water

Peruvian_Andes.jpgCordillera Blanca Mountains in the Peruvian Andes, copyright Dozenist.
The Andes Mountains in Peru have the world's largest mass of tropical glaciers, and most of those are located in the Cordillera Blanca Range.  Glacial melt-water finds its way to the Santa River, a significant source of water for the hundreds of thousands of people who live in the cities of this region, including Lima.  This water is also important for local agriculture, as well as one of Peru's largest hydro-electric projects.  But a new study by a team of scientists, including Dr. Jeffrey McKenzie, a Hydrogeologist from McGill University in Montreal, has found that the glaciers of the Cordillera Blanca are receding rapidly, and have been for at least ten to fifteen years, due to climate change.  Some have even disappeared, while other glaciers have crossed a threshold called 'peak water,' which means they are melting faster than they can be replenished.  The growing shortage of water has already created conflict among a growing population, and scientists are concerned that unless more efficient uses of water are employed, the situation will only get worse.      

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The Enemy of my Enemy of my Enemy

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Hyper-parasitoid wasp, courtesy N Fatouros
Untangling the complicated relationships between predators and prey is a tricky job.  Take, for example, the system Dr. Erik Poelman, from the Laboratory for Entomology at the University of Wageningen in the Netherlands, has been studying.  He was investigating the response of cabbage leaves to predation by caterpillars.  To help defend itself, the cabbage emits chemicals to summon a parasitic wasp to attack the caterpillar.  But Dr. Poelman has found that it doesn't end there.  When an parasitized caterpillar feeds on a cabbage leaf, the chemicals emitted attract another "hyper parasitoid" wasp that attacks the parasitic wasp.

 

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Near Earth Objects

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Space is very empty, but there's more than enough in it to worry about.  Asteroids and comets have struck the Earth in the past, with catastrophic and history-altering impacts.  In the past, there's been little we might do about this. But that's now changed, according to Dr. Don Yeomans, Senior Scientist at the Jet Propulsion Laboratory and Manager of NASA's Near Earth Object Program Office.  In his new book, Near Earth Objects, Finding Them Before They Find Us, Dr. Yeomans explains the source of all these Earth-threatening objects, and how he and his colleagues are finding and tracking the potentially millions of objects that might one day threaten us.  He also explores strategies for intercepting them, so that we can avoid the fate of the dinosaurs.

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Theme music bed copyright Raphaël Gluckstein, Creative Commons License by-nc-nd-2.0