Lobodon!: Counting Lobos Marinos

For the past several days I've been settling in at CADIC, and learning how to live the Ushuaia life. My host Pancho drove me through the icy streets earlier this week to the closest supermarket, Carrefour. It's like a mini-Costco for South America. I stocked up on my usual staples, though there's no peanut butter, or at least I didn't see any. Guess I'll have to change my lunch routine. I bought pasta and what I thought were a couple cans of tomato sauce, but turns out they were canned whole tomatoes. Certainly made my first homemade pasta dinner different from what I'm used to. The supermarket is a decent walk away, and since the sun rises around 10 and sets around 5, I haven't yet made the cold dark trek there yet. I'll be able to tomorrow, to stock up for my own personal Independence Day celebratory American style burger surprise.

Even though I saw it coming, I have to admit that it's jarring going from the hot, dry sunny drought-stricken California summer to the cold, dark wet winter in Ushuaia. Pancho informed me that this winter has been particularly harsh and snowy compared to normal, saying that it's usually much drier this time of year. Light feels like a premium here and unfortunately my work hours overlap entirely with the meager sunlight, so I haven't been outside much at all yet. I plan to make up for it this weekend. I'll be hitting the ski slopes with some grad students and exploring the town, so expect another post a few days from now about that.

Most seal bones come from layer D, but there are a few from E and F, too

In any case, I wanted to post something about how the research is going and how quickly research priorities change once you have access to the materials. I've spent most of my time poring through the database/catalog of seals, cutting out specimens that are lacking in information about their sex or age. From an original amount of nearly one thousand seal maxillas, premaxillas, and maxillary canines (the bones and big teeth that comprise the front of your face between your nose and upper mouth, from which ages and sexes were originally determined by a PhD student in the 90s), I filtered it down to 364 ideal candidates. I then went through and opened a bags upon bags upon bags of neatly organized bones, categorized by the the exact layers of dirt they were excavated from (as seen in the stratigraphic figure attached above). By the time I finished going through the bags, I had only found 158 bones. What was going on? Where were all the others?

158 South American Fur Seal maxillas waiting to be be demineralized

Turns out the missing samples were only teeth, and since I was only looking through bones, all I found
were bones. Teeth require different methods for analysis since they hold very little collagen compared to bones. I threw together a quick graph to see if I had enough bones. Luckily I have enough bones represented different age classes and sexes so I can justify statements about the entire population and look at specific bits of seal life history (aka ontogeny). Pancho and I agreed that 158 samples are enough to extract ecological information considering the samples cover all parts of their life history. I can't wait to see what isotopes will have to say about their feeding habits and movement during different stages of their lives.

One aspect I really enjoy about my career is that I not only get to identify what may be happening to populations as a whole, but also get to do a little forensics too. One individual, #34222, was clearly sick during his lifetime of around 12 years. Before he was butchered and thrown into the site now known as Tunel I by Tierra del Fuegans some 5,000 years ago, he clearly had some abnormal growth on his face. It likely began early in his life since his nose grew off to the right around the tumor. Have some pictures!