La Campaña: En la Casa

A late afternoon view toward the Southwest from Moat Bay. Isla Picton with Isla Navarino in the background, the opening of the Beagle Channel to the Pacific in the west (right).

Buenas tardes folks,

Now that its been a few weeks and I've settled back into the routine here in Ushuaia, it seems like a good idea to describe in some detail what life was like, what I learned and how I'm moving forward as a result of this fieldwork.

You should know by now I'm interested in studying food webs and ecology using remains of hunted fur seals and sea lions from archaeological sites. While it's possible I could've just gone and asked my colleagues to just send bones to me in the US, that would've been no fun and I'd be missing out on understand how and why these bones showed up in the first place, both in the context of the culture of the peoples who hunted them and in the natural climate and taphonomic processes. Over the month I was in the field, being outside everyday, I not only learned what it was like to live as an Argentine in Tierra del Fuego, but also what weather the Yamana may faced (which was not very much like California).

Rain over the Beagle Channel, looking Southwest. Moat Bay extends to the left, while our ranch and nearby lake are on the right. The dirt highway, Ruta J, continues for about 20km to the east before ending.

From Ushuaia, which is near the middle of the Beagle Channel, we packed up some trucks with nine people and our gear for the month; three professors, three graduate students (including me), two undergraduates working on their senior theses, and a lab assistant. After we piled in we drove 3-4 hours east of Ushuaia, past Estancia Harberton, to Moat Bay. Moat bay is located at opening of the Beagle Channel to the Atlantic Ocean, which provides a stunning view of Islands to the south in Chilean territory; Isla Nuevo, Lennox, Picton, and Navarino.

A rainbow over our ranch house, during our daily afternoon water refill routine.

We arrived at a remote ranch, and luckily for us we had a guest house to stay in. Despite having a kitchen, bathroom with a flushing toilet, and generator for power, there was no running water as the pump had broke. As a result, we carried buckets of water from the nearby lake and drank water from the rain that collected in a barrel off the roof. The lake water had a bit of an algal taste, and was preferred by some of our members to the rain barrel water, which had a distinct "wooden barrel aged" taste, even though the barrel was plastic.

Our fully stocked kitchen at the beginning of the campaign.

Generally, we'd wake up around 8 most mornings, after tough days or celebrations we might sleep until 9. We'd have a light breakfast of coffee and tea, bread and jam or butter, or if lucky facturas (basically donuts) that were brought by visitors or our members who had left and come back. When we ran out of bread, it was a sad day since we were left with crackers and maybe some cookies. But usually that was a short lived experience because someone would show up at the ranch with a fresh resupply of bread and pastries, and maybe even wine or beer!

Lunches were also fairly light, we'd generally eat a mix of bread, cheese, crackers, and dried sausage or salami; some fruits and vegetables, like salad, carrots and apples, followed by cookies and chocolate. Later on we needed to use our leftover pasta, so we'd cook some at our field sites. We generally also snacked on crackers and cookies while working, but careful not to drop any food in the field pits. Lunch is a later than what I'm used to, usually around 1, but sometimes later. We'd spend about an hour on break. And, of course, we wouldn't have survived without Mate, the shared Argentinian tea-like beverage which helps keep you working. We generally drank mate continuously throughout the mornings and afternoons. 

When we returned back to the ranch house and were exhausted, we would go get more water from the lake, maybe take a bath or at least wash our hands and face, and make some more coffee and mate. On more difficult days we'd have fernet and coke, the favorite drink of Cordoba (a province in Argentina) and the Porteños (the residents of Buenos Aires) from which almost everyone in our group shares culturally. 

A fine chicken dish in a big wok!

Dinner in Argentina is late. You might start cooking at 9, and start eating at 10 or later. We'd break open boxes of cheap wine (easier to transport in the field, and easily disposable containers) and have different kinds of meals. Sometimes it was a meat or fish stew (giso), sometimes pasta (with ñoquies, a potato derived noodle), pizza or the famous Asado (steak BBQ). In any case, dinner was always much appreciated and we ate well. Afterward, if we had enough energy, we'd sit to play a game of cards or dice, usually jodete or generala. After that we'd be truly exhausted and hit the sack, meaning a pile of sleeping bags laid out on the floor of the living room in front of the warm pot bellied stove.

Until next time, here's some highlights from the house area:

Starting up the truck in the morning...easier said than done

And starting up the generator in the evening

Practicing the recorder, taking a walk during some downtime while the weather was good. You can see the ranch house in the background. 

Sorting out a knot problem on the living room floor

The hummocky road leading to the beach, facing south from the house.

Another view of that (double) rainbow to the east, showing the length of Moat Bay

Vuelva a Ushuaia

Ushuaia Bay upon landing

Hello once again!

I figure it's a good time to start writing again since it's been several months since I last updated the blog. Quite a bit has happened in the intervening months. I've ran the South American fur seal samples I collected and they've provided some puzzling results. I measured the carbon and nitrogen stable isotope from the bits of processed seal bits (collagen if you recall from my previous posts). Stable isotopic values of various elements will show you varying characteristics of the world based on how they cycle through biogeochemical systems (and an animal's biochemistry). Carbon and nitrogen are particularly useful for measuring ecological characteristics, like finding out one's trophic level (if you are a vegan, vegetarian, or a meat eater.)

When interpreting the results of these isotopic values, there isn't much of a basis for comparison if you have nothing to compare against. In classical studies, you need to know what the values are at the base of the food chain as well as potential dietary components of your study animal. Even without this info, there are some inferences we can make. There are some noticeable differences between male and female fur seals from 6400 BP, but age did not seem to have a large effect. Most of the fur seals seem to cluster together toward a lighter carbon isotopic ratio.

Pulled from the latest version of my proposal

Based on literature values of fur seal dietary components from modern collections, I can see if diet corrected values of my ancient seals fall within expected dietary boundaries of modern fur seals. Essentially, you connect the dots of the most extreme dietary values, creating a diet polygon, and should see your animal's diet corrected values fall within the polygon. From there you can create an isotopic mixing model to see which dietary components contribute the most to the animals diet. For example, I should be able to see if the seals are eating mostly squid or mostly fish.

Alas, this is not what happened when I compared modern diet to ancient animal. There has clearly been some kind of shift over time as none of my seals fell within the diet polygon. Modern dietary components are much lighter in carbon than the more recent seals. Something has changed in the carbon. One might argue "Hey wait a sec, what about the Suess effect?"

The Suess effect is a change in the ratio of the atmospheric concentrations of heavy isotopes of carbon (¹³C and ¹⁴C) by the admixture of large amounts of fossil-fuel derived CO₂, which is depleted in ¹³CO₂ and contains no ¹⁴CO₂.

However, I had already applied a Suess affect correction based on literature values, and not including this correction would have actually made some of the individuals fall within the diet polygon. In any case, I have more work to do grappling with this issue and doing some ANOVAs.

Analysis of variance (ANOVA) is a collection of statistical models used to analyze the differences among group means and their associated procedures (such as "variation" among and between groups), developed by statistician and evolutionary biologist Ronald Fisher.

Ok enough Wikipedia citations. My guess at the moment is that there's been a shift in the base of the food web over the years and seals are probably eating roughly the same things that were 6400 years ago. I won't be able to find out whether that's true or not until I find some way to measure the base of the food web, either by looking directly at animals near the base of the food web (preserved in the archaeological record) or by looking doing compound specific amino acid stable isotope analysis of seals over time. The idea is that certain amino acids do not change in as they move up the food web as they undergo minimal chemical reactions (aka source amino acids). I just got to try out this technique before leaving Merced, and while it's certainly time intensive I plan to do a lot more of it when I return.

Also I will be leaving for fieldwork (ie. doing Indiana Jones style excavation of sites) in two days at a place called Moat Bay for almost a month. I'll be taking lots of pictures, but I won't be able to post them until I return. Expect some lots of photos in the future!