Tag Archives: Stable Isotopes

A tale of two penguins

The Antarctic Peninsular is regarded as one of the fastest warming regions in the Southern Hemisphere.  It might seem small to you, but the increase in air temperature of around 2.8 degrees Celsius is resulting in some big changes.  According to the British Antarctic Survey some 25,000 square kilometres of ice has been lost from ten floating ice shelves, 87% of glacier termini have retreated, seasonal snow cover has decreased.  What exactly these sorts of changes mean for the inhabitants and seasonal visitors to the Peninsular is a question researchers are desperately trying to get a handle on.  The way each species reacts to this changing environment is likely to be very different, even among closely related species. Continue reading A tale of two penguins

Rise in industrial fishing correlated decline in size of petrel prey

It makes sense that industrialized fishing has altered marine food webs, but understanding exactly how it has can be challenging.  We don’t have that much in the way of background data on what – and how much – was swimming about the oceans before industrial fishing began – let alone a full picture of what is there now.  We also lack a full record of who was fishing what, when, where and how much they were taking.

For Dr Anne Wiley and colleagues at Michigan State University…challenge accepted!  A little out of the box thinking saw the team delving into the nitrogen-15 and nitrogen-14 isotopes in the bones of the endangered Hawaiian petrels.  Using stable isotopes, scientists can figure out exactly where in the food chain these birds have been feeding.  And because the isotopes remain in the bones the team were able to compare the diet of modern-day petrels with petrels that were flying around hundreds and even thousands of years ago.

Pretty neat huh.

What they found was that the petrels used to feed on bigger species quite high up in the food chain.  So what happened when industrial fishing began?  With this new and efficient predator, the petrels switched to catching smaller prey from further down the food chain.

For those with access to the journal PNAS, the original paper can be found here http://dx.doi.org/10.1073/pnas.1300213110

Image: Lead author Anne Wiley with a newly discovered, ancient Hawaiian petrel skull from Puu Naio Cave, Maui. After radiocarbon dating, the team learned that this bird died around 1400 A.D.  Credit Andreanna Welch, kindly made available for release with the paper