Couldn't resist...

And that's all for today, folks.

Ode to a Mass Spectrometer

For my dissertation, I am focusing on two techniques that rely heavily on (read: could not happen without) an incredible scientific instrument called a mass spectrometer.  These amazing machines don't often get much love from the common person (even many of the scientifically minded ones) because, I believe, they are intimidating.  The name alone is too esoteric for many people to approach, thus they don't even want to think about the inner workings and the functions of the machine.  So, this post is an effort to make these fascinating instruments a little more accessible and maybe even earn them a little more love and respect from the public.

*DISCLAIMER* - I am not an expert in the design, construction, maintenance, or even operation of these machines.  I will likely make an error somewhere in here, so be gentle if you are one of the aforementioned experts.

Now that we've gotten that out of the way, let's get to the nitty gritty.  I'm going to take you all the way back to your elementary chemistry class.  Don't worry, we're going to stay very basic here.  Remember atoms?  I hope so.  Atoms consist of a nucleus (containing protons and neutrons) and a very complicated "probability cloud" of electrons which we aren't even going to touch with a ten foot pole so don't worry.  Of these three particles, only protons and neutrons have mass.  A typical carbon atom has 6 protons and 6 neutrons, thus it's atomic weight is 12, whereas a typical nitrogen atom has 7 protons and 7 neutrons and it's atomic weight is 14.  Each element has a different number of protons and neutrons in its nucleus (which is what makes it a different element in the first place) and, because of this, a different atomic weight.

So, if we want to look at an object or some material (oh, let's say walrus bone collagen), and determine how many of each different type of atom make it up, how would we even go about doing that?

The ingenious answer developed by a long line of ingenious people too long to list here is known as the mass spectrometer. Behold:

It actually looks pretty simple, right?  The basic principle is this.  You take whatever material you are interested in studying and you set it on fire.  We're off to a good start, right?  After combustion, the resulting ionized particles (the atoms that made up your material, pre-combustion) are whisked away down a tube under vacuum.  The tube makes a bend and, at that point, an electromagnet subjects the particles to a strong magnetic field.  Lighter particles have less inertia and their paths are curved more sharply than heavier particles, which have greater inertia (due to their greater mass).  After making the turn, the particles continue traveling, now separated by mass, and smash into a detector.  This detector registers how many particles hit it in different locations and is programmed to know which location correlates with which atom.  Voila!  You now know what your material was composed of.

Excited yet?

Now, to make it just a tiny bit more complicated, we can also use this technology (as I do) to study stable isotopes.  I said before that a "typical" carbon atom has 6 protons and 6 neutrons.  Well, not all atoms are typical.  Some have more neutrons than they are "supposed to" and these different variations are called isotopes.  Some are stable and some are not.  The ones that aren't undergo radioactive decay (e.g. all the scary radioactive materials you have heard of like uranium-235 and plutonium-239, though the vast majority of them aren't dangerous in that sense and haven't been used to make weapons).  As an example, here are the two stable isotopes of hydrogen:

Mass spectrometers are so good at what they do, that they can separate out and distinguish between not just different elements, but also the different isotopes of the same element!  This, by the way, is the technology that makes possible not only my work but a huge field of study spanning a wide variety of disciplines.

Well, that's it.  Thanks for reading!  Hopefully you learned something.

Casey and the Walruses

I recently realized that my blog's title is a little outdated, though I suppose my scope was a little narrow to begin with.  Casey and the Marine Mammals doesn't have the same ring to it.  Casey and the Marine Ecological Studies?  I don't think so.  The URL would have been much too long.

It bears mentioning at this point that my whale days are not quite over, as I am still working on publishing my manuscript from my MS thesis.  It has been a long and arduous process, which has definitely motivated me to write my PhD chapters in manuscript form.  I never would have guessed it would be so difficult to pare a thesis chapter down into a clear, succinct paper.  In light of these difficulties, I am happy to announce that a little side-project that developed in conjunction with my master's project was recently published in Marine Mammal Science:

Check it out here!

Thanks to Liz Vu and all our awesome collaborators for getting that one to press.  It's fun when science works the way it's supposed to.  In celebration, here's a picture of some humpbacks enjoying the crystal clear tropical waters of Hawaii.

I wish I could say I was doing the same, but I am definitely not.  Still dark and cold here in Fairbanks, but after today it will only be getting brighter!  Happy winter solstice everyone!

The Story of My PhD

So you may be wondering how a marine mammal biologist can be undertaking a PhD project in which there is all likelihood that he will never see his study species.  I must admit, I've asked myself that question once or twice over the past 6 months, but really the answer is quite simple.  My doctoral work is primarily concerned with animals that are already dead, be it for one year, 50 years, or 2000 years.  Here's the run down:

My dissertation is part of a larger project called, unsurprisingly, WALRUS, a large-scale collaborative project aimed at understanding the impacts of changing climates on Pacific walruses.  By investigating how historic (and prehistoric) changes in climate impacted walruses, we hope to gain a better understanding of the effects current and future climate change on today's Pacific walrus population.  To this end, we are using samples from modern (stranded dead or subsistence harvested by Native Alaskans), historic (housed in museum collections), and prehistoric (recovered during archaeological digs) walruses to study how their migratory movements, feeding behaviors, genetic diversity, demographics, and even stress levels have changed over the past 2,500 years.  The impetus behind this work comes from changes in walrus behavior observed in recent years, namely the hauling-out of thousands of walruses on land, which have garnered a lot of recent media attention through stunning photos like this one:

Source: Chukot-TINRO

These haul-out events are thought to be the result of a lack of available sea ice habitat, and can lead to overcrowding, trampling of smaller animals, over-exploitation of food resources in a localized area, and increased sensitivity to disturbance by humans and/or land predators.  As a result, scientists, wildlife managers, and conservation groups have become concerned about the health of Pacific walrus populations.  The WALRUS project is designed to provide these groups with a better understanding of just how adaptable Pacific walruses are to changing climates and will hopefully give us an indication of just how dire the current circumstances are for walruses today.

My specific niche within this larger-scale project is yet to be determined, but it safe to say at this point that there will be plenty of work for me to do over the next 3+ years.  Maybe this time I'll do a better job of keeping you, my loyal readers, updated on my progress.