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Past Shows
November 4, 2006
 Download an MP3 of the entire program (22MB) (available Saturday, two hours after broadcast).
The End of Fish?
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Will our fish be gone by 2050?, Courtesy, CBC Online |
The idea our ocean fish stocks are threatened is nothing new. But the immediacy of the problem was highlighted in a paper published in this week's edition of Science Magazine. Dr. Heike Lotze, a Canada Research Chair in Marine Renewable Resources in the biology department at Dalhousie University in Halifax, was part of the team that wrote the paper. They looked at historical data, and experimental data going back up to a thousand years, to determine how biological diversity is changing in our oceans. They found that we're destroying ecosystems at a rapid rate, and, if we continue in this vein, the fish we harvest today will be gone by 2050. Also, the oceans will become very different places, with no large mammals, very few fish of any kind, and a decrease in the variety of seabirds. They're not entirely pessimistic, though. Dr. Lotze and her colleagues believe we can turn the situation around with proper fisheries management.
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Rethinking Dinosaur Flight
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Artistic rendering of Archaeopteryx - Courtesy, Nick Longrich |
When Archaeopteryx was first discovered, it quickly became one of the most important fossils ever found. With the skeleton of a dinosaur, but the feathers of a bird, it provided the first solid link between the two groups of animals. Today, the line from dinosaurs to birds is well accepted, but it doesn't mean the skeletons don't have secrets still to be revealed. Nick Longrich, a PhD student at the University of Calgary, recently uncovered one of these secrets: that Archaeopteryx had flight feathers on its back legs. This changes our picture of how these birds flew, although exactly how the back legs were involved in flight isn't clear. It does suggest, however, that birds probably developed flight coming down from the trees, rather than by jumping into the air.
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Toadfish Pee
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The toadfish - Courtesy, J. Barimo |
Most organisms need to get rid of bodily waste at regular intervals, and usually it’s just excreted and the animal moves on. Except for the toadfish. Not one to be wasteful, the toadfish has come up with a way to put its own waste to clever use. While most fish pee is in the form of ammonia, the toadfish produces a mix of ammonia and urea -- which is the kind of urine most land animals, like ourselves, produce. But producing urea is an energetically expensive form of waste that land animals produce only because ammonia is toxic in their environment. That's not the case for fish, and that had Dr. Patrick Walsh wonder why the toadfish would go to such lengths. It turns out the ammonia attracts predators, but by mixing in equal parts urea, the predator can’t track the toadfish. So while most fish would excrete their ammonia and quickly move on, the toadfish uses its pee as a chemical cloak. Dr. Walsh is a professor of biology at the University of Ottawa and holds a Canada Research Chair in Environmental Health and Genomics.
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Bird Doping
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Semipalmated sandpiper |
The Semipalmated Sandpiper has tested positive for a performance-enhancing chemical. These tiny birds make a 4,500-km overseas flight to their southern wintering grounds, which is only possible because of a supplement they ingest. By gobbling mud shrimp in the Bay of Fundy for two weeks before their trip, they take up a special fatty acid that changes their cellular metabolism, allowing them to perform their extraordinary flight. Dr. Jean-Michel Weber of the biology department of the University of Ottawa blew the whistle on these tiny birds.
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The King of Infinite Space: Donald Coxeter
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King of Infinite Space, by Siobhan Roberts |
The works of Dr. Donald Coxeter are some of Canada's most important contributions to the field of mathematics. For almost all of his adult life he taught geometry at the University of Toronto. While the rest of the mathematical world turned away from geometry as a useful tool, Dr. Coxeter persevered. In his later years, his work reemerged from obscurity, as the importance of understanding an object's shape was recognized in everything from biology to computing. Along the way, he inspired such diverse fields as art, through the Dutch artist MC Esher, and architecture, thanks to R. Buckminster Fuller. Dr. Coxeter died in 2003 leaving behind a huge legacy and a reputation as the man who saved geometry. Siobhan Roberts, a freelance writer in Toronto, met Dr. Coxeter in his later years, and has just published her biography of the man. It's called, King of Infinite Space: Donald Coxeter, the Man Who Saved Geometry and is published by Anansi Press.
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Question of the Week: Pluto and Neptune's Orbits
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This week we have a question that’s out-of-this-world, from Keith Poore in Belle River, Ontario, who asks: How often do Neptune and Pluto intersect orbits? And when will they collide?
For the answer, we go to Dr. Brett Gladman, associate professor and Canada Research Chair in Planetary Astronomy at the University of British Columbia.
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