Viviendo

A rainbow rising from the Beagle Channel

Apologies for the late post here, there hasn't been to much new information to report since the last time I updated. However, there is still plenty I can share with you!

Simple but dependable kitchen

Lately I've been living the CADIC life, which has a nice hotel like space for visitors like me and actually has shared apartments for students who study here. It's simple living, but definitely comfortable. The old gas stove heats up my food maybe a little too fast, but it works! Last weekend the power went out, but I managed well enough cooking in the dark. This time of year there aren't very many visitors so I've had the kitchen and dining room to myself. I end up spending most of my spare time in the office since the internet doesn't really make it to my room (short of holding my phone next to the window) and really only venture out into the world when I need to go shopping. I would go out more often, but by the time I'm finished working for the day the sun has long since set, and its too dark and cold to really enjoy sight seeing. At the very least the weekends give me an opportunity to explore the town a bit and to get to know people. This weekend I'm planning on taking a walk across town to check out the maritime museum, located in the old prison. I'll be sure to share more details about that later on. Today I discovered that the shower is actually capable of getting hot and not just lukewarm, it turns out that I wasn't waiting long enough for it to reach temperature. Knowing this will make my life much more comfortable!

The dining room, straight out of a 70s designer catalog

Over the time I've spent here, I've been learning a ton about the species of seals I'm studying. As it turns out, there's still quite a bit unknown about fur seals and their evolutionary relationships, which strikes me as somewhat odd given that they're common large mammals occurring in many different oceans (Pacific, Atlantic, Indian and Southern.) The majority of Fur seals live in the southern hemisphere, except for one species off of California, the Guadalupe Fur seal, very nearly driven to extinction in the 19th century. Pinnipeds (all seals and sea lions) are divided into two groups: Otariids and Phocids. Fur seals are joined by Sea Lions in Otariidae, while true seals are in Phocidae. My Californian friends are probably familiar with the Otariid California Sea lion, which tends to bark very loudly and keep people up at night. You'll notice that Otariids have ears that stick out and can pose upright, supporting themselves on their front flippers. True seals, Phocids, are unable to do this and are also missing those ear flaps, signalling potentially stronger adaptations to the marine environment.

A picture of A. australis I found on the internet

In South America, only Otariids exist today (except for lost or wandering Antarctic or sub-Antarctic Phocids, and a small colony of southern elephant seals hanging out at the very south-eastern edge of the continent).  Phocidae once had a significant presence in South America, however changing sea levels during past ice ages effectively removed the open beaches that they loved so much several million years ago, leaving behind only rocky shorelines. A-ok for Otariids, bad for Phocids. Some Otariids that took over during this time were the Fur seals, which proliferated throughout the whole southern hemisphere, diversifying into at least six different species in South America, Australia, New Zealand, South Africa, and the sub-Antarctic islands. In 2011, researchers proposed re-classification of most of the fur seal species into a new genus: Arctophoca, (formerly Arctocephalus, only Arctocephalus pusillus kept the genus name) based on a review of genetic data.

The taxonomic situation gets even more tricky for my primary target species, Arctophoca (née Arctocephalus) australis, the South American Fur seal. In the mid 20th century, Judith E. King proposed two subspecies based on comparison of two skulls from the Galapagos and the Falkland Islands. This classification never really stuck though since the skull from the Galapagos was deemed to be a separate species completely (the Galapagos Fur seal) and for many years no subspecies were considered, despite the huge geographic range of A. australis, stretching from northern Chile to Uruguay. In the same review of genetic data that reclassified the genus of most Fur seals, the authors found that the South American Fur seal could have as many a four different subspecies, though more data is needed to confirm these distinctions. At the very least there are three different evolutionarily significant units (ESUs) of A. australis, occurring in northern Chile, Tierra del Fuego, and Uruguay. Interestingly, most of our knowledge about the A. australus comes from the huge colony that lives by Uruguay. The seals from here have smaller body sizes than the seals to the south, potentially hinting at a phenotypic indicator of differences between ESUs (and possibly subspecies). 

The uncertainty about some of these evolutionary relationships has intrigued me to the point where I'm getting serious about another type of analysis that will be helpful: Ancient DNA extraction. I plan to bring back some samples to do a test run to extract ancient mitochondrial DNA. If successful, I can use ancient DNA not only to disentangle some of these complicated relationships between the ESUs, but also find out how the population of Fur seals in Tierra del Fuego has changed over time, from 6,000 years ago to present.

Weighing time

In more other science news, I'm starting to get really busy on the isotope side of things. While I'm demineralizing the last set of bones, I've begun weighing pieces of dried collagen to find out how much is actually left after all that chemical treatment. So far, it appears that I've recovered amounts consistent with previous extraction runs, which is excellent. The weighing step is easily the most time consuming and boring, but it does allow me to listen to a lot of music and podcasts. After measuring the collagen yield, I place a small amount of the collagen into very tiny tin boats, which will later be incinerated at around 900 degrees C to measure those carbon and nitrogen isotopes I'm after. I'll write more about what happens next when I'm back in Merced. 

A closer look at the tin capsules

In a future post I intend to talk a bit about the post-European contact history of A. australis and a bit about the Sea lions. which has important implications for my research! Also some Ushuaia (prison) history. Stay tuned!

ácidos y bases

Ushuaia from the oven room window

Today was my Argentine lab-mate Daniella's birthday (Feliz Cumple!) and so the various members of different labs and offices nearby congregated in the kitchen to exchange gifts, eat delicious cake, and pass around bottomless cups of coffee and mate. This is the third birthday that's happened since I've arrived here, and I'm beginning to think that these aren't really birthdays. People just like to have cake every few days. One of the professors joked that I must be thinking along these lines, apparently there's just a high concentration of birthdays this time of year. He continued to say their new hiring criteria here is that your birthday isn't in July, presumable to prevent endless cake eating. In any case it can be nice to have a break every once in awhile from working in the lab and reading papers.

A bone sample in acid solution

Over the last week and a half I've been checking the samples everyday. To measure trustworthy dietary information from bones, there are a few steps that need to take place. Like I mentioned previously, I'm interested in the bone collagen since collagen exclusively records diet. In order to get at that collagen we need to first dissolve the bone mineral around it (bioapatite for short), in a process known as demineralization or acidification. For smaller pieces of bone, like the ones I'm demineralizing, you use a fairly weak concentration of acid, just 0.5 molar (M) Hydrochloric acid (HCl). (For comparison, the concentration of HCl in your stomach is around 0.1 M.) This slowly dissolves the bioapatite so you can prevent it from dissolving the collagen, too. After 24 hours the HCl has completely reacted with bioapatite, releasing carbon dioxide gas, so a new acid solution must be applied until nothing but collagen is left. (Don't screw the caps on completely, that gas will eventually escape catastrophically, blowing those caps off in the middle of the night). Others will use a weaker concentration of HCl, 0.2 M, though this will take longer. I could dissolve the bones in a few minutes with the raw 12 M HCl, but it would likely take the collagen along with it. It took two days with the 0.5 M HCl for my bone samples to be reduced to collagen, which retains the shape of the original hard bone, but is now soft, spongy and rubbery.

Humic material extracted from old seal collagen

Most people tend to wash their hands if they put them in the dirt after a few minutes. What do you do if they've been sitting in dirt for several thousand years? As the soil scientists at UC Merced can attest to, soils are home to quite possibly the most complex and unknown ecosystems on Earth, hosting vastly diverse organisms and an incredible number of species. These microbial communities often vary considerably from place to place, seasonally, and even diurnally (thoughout the day). The most significant byproduct of soil microbes, or the byproducts that can create untrustworthy stable isotope values in any case, are humic acids, a general term that characterizes the extremely complex (and acidic) organic compounds that are excreted by these microbes. Apply a weak base for several days though and you rectify several thousand years of microbial waste. After some rinsing of the remaining collagen with water and application of 0.1 M Sodium hydroxide (NaOH) for several days, your collagen bits are as good as new! Each individual bone varies in how dirty it is, so those with very little humic acid will be ready after 24 hours, others might take up to five days.

Samples about to be dried in the oven

The next step in the process is to dry the collagen samples. Now that the collagen has been sitting in liquids for the past week and half or so, they're quite waterlogged. What better way to dry off than to be cooked at 55⁰ C (135⁰ F) for 24 hours. Afterward, the samples are ready to weighed to account for the collagen percent yield, which tells us how well preserved the bones are (which hopefully will be around 25% for every sample). Then I will weigh a tiny amount (1 mg, from original pieces of 150-250 mg) into 3x5 mm tin boats, ready to be analyzed by the element analyzer and mass spectrometers in the Fogel lab back at UC Merced.
 
So far I've been limited to 82 samples, since that's how many plastic vials I have. Now that those plastic vials are mostly free again, I'll start this process again with the remaining unprocessed 78 seal bones. Hooray!

When not working in the lab, I've been discussing background material and general ecological and archaeological information related to my project with Pancho, and possible directions where I can fill in gaps in our understanding of the evolution of this ecosystem over the last several thousand years. In a future post I plan to talk about the ecology of Tierra del Fuego and some ideas I'm playing around with. Stay tuned!

El Intercambio de Arquelogía y Ecología

Sunrise at CADIC

Today I was lucky enough to visit el Parque Nacional Tierra del Fuego with Pancho and his graduate student Pili to learn a bit more about both the environment and the Yamana (the indigenous people in southern Tierra del Fuego) who have lived here for thousands of years. Pili is studying how the Yamana processed seals after catching them by looking closely at the cut marks and various other human produced scrapes and scratches, carefully noting changes in how the seals were butchered over time. Thus, she is an excellent companion to have around, and with Pancho, provided me much insight about some of the characteristics and practices of the Yamana. Despite the abundance of archaeological sites here, there is still quite a bit of unkown information about these people, especially their ancestors from several thousand years ago.

There are number of ethno-historical accounts describing the culture and lifestyle of the Yamana written by British missionaries from the 18th and 19th centuries, however it can be problematic to extrapolate this information into the deeper past, not only because these first European contacts tended to exaggerate stories about the cultures they encountered, but also due to the fact that culture is constantly evolving and changing. The Yamana of 18th century were certainly very different from the Yamana of 6000 years ago, even if many of their tools and physical patterns of settlement only show subtle differences. We are unable to identify most of those potential differences since we are left with a scant record of artifacts and other archaeological data since the Yamana had no written language.

Nothofagus trees, with lichen that guanacos love to eat in winter

Despite this, we know that the Yamana were extremely mobile marine resource intensive hunter-gatherers, moving in small familial groups from site to site every few weeks. They would fashioning harpoons tips made of whale bone scavenged from beached whales to 3-4 meter long wooden poles from Nothofagus trees (a relative of oaks, for those of you familiar with trees from the northern hemisphere.) The Yamana of the Beagle Channel would paddle out to sea in their canoes (made from Nothofagus bark) and launch their long harpoons into their preferred targets, Arctocephalus australis, the Southern Fur seal. They would follow their targets until they died from their wounds, unable to dive with the large poles keeping them afloat. The fur seals, unlike other marine mammals, were small enough to fit in their canoes to bring to shore.

Once on shore, the Yamana would butcher the seals with bone and rock tools. (Some early stone tools were made of obsidian only found far to the north, evidence that the early peoples may have been more mobile than the more recent Yamana.) After this work was finished, a few remains, broken tools, and various other bits of unneeded materials were thrown to the side. Typically, working and living sites are identified by a circular pattern with the refuse all around the sides, creating pits in the middle. The vast majority of artifacts used to study these cultures come from the sides of these pits.

Bahia de Lapataia, connected to the Beagle Channel in the background

Why am I telling you all this? Today's goal was to go see some of these pit sites in person. Originally we planned to go the Tunel I, where all my seal samples came from. But a snowstorm yesterday made the 40 minute walk to the site impassable. Instead, we went to the national park were there are a number of other sites and things to see. One very popular tourist attraction, the Bahia de Lapataia (Lapataia Bay) has a number of raised boardwalks that prevent people from disturbing the numerous shell middens and pits underneath. (Midden is the archaeological term for "trash pile"). This particular site is so extensive and has so many shells that the soil chemistry has been altered, resulting in grass that grows in a different color. Unfortunately, these sites were all buried in snow so I couldn't see anything underneath the boardwalk, but I should be able to during my next trip south.

El Rio Lapataia, connecting Lago Roca to Bahia Lapataia

Another very cool place with an exciting geological history is the freshwater lake Lago Roca, which feeds a short, shallow and wide river that dumps into Bahia Lapataia and the Beagle Channel. I should state that all of Tierra del Fuego has an extensive glacial history, almost the entirety of the landscape here was influenced by glaciers during the Last Glacial Maximum (often abbreviated LGM, occurring roughly 25,000 years ago.) Glaciers carved not only the valley in which Lago Roca lies, but also the entire Beagle Channel. The lake is only at an elevation of 2-3 meters above sea level, hinting at its history as a fjord connected to the ocean after the glaciers retreated. Geologists believe that the fjord was cut off from the ocean about 6,000 years ago, leading to the formation of the lake. Archaeologists, however, contest this date since they find sites with shell middens (marine shells, mind you) from 4,000 years ago along the lake shores. While early peoples could have transported these shells inland, that would be inconsistent with observations found in other parts of Tierra del Fuego. In any case, it's very pretty and is a popular spot among hikers, canoers and kayakers during the summer months.

Looking toward the north shoreline of Lago Roca, where many shell middens are found

Looking at the south shoreline of Lago Roca, which marks the boundary with Chile

I was planning to write a bit about how the chemistry side of seal analysis was going, but this post seems pretty long and full of info already, so I'll save that for a post later this week. Stay tuned!

Esquiando y Trabajando

A view from CADIC toward the harbor

A lot of delicious meat food

I hope you all had a great 4th of July weekend! While I certainly missed having hot dogs, hamburgers and watching fireworks, I had an excellent, but very different and Argentinean version of the holiday weekend. Saturday afternoon I was introduced to a ton of new faces, quite literally. In Argentina, like much of the Spanish speaking world, you are expected to kiss people (and not just the ladies) on the cheek when being introduced, saying hello, goodbye. Any reason is an excuse really. So I've been slowly getting used to that even though some people realize I'm American and just shake my hand (or perhaps they see the awkwardness in my eyes.)

Despite this, or perhaps due to the natural inclusive nature of Argentinians, they invited me to delicious steak barbecue, or asado as its known here. I've learned that traditional Argentinian food is pretty much just meat. Delicious lightly seasoned meat, slow cooked for several hours. Usually you drink it with wine, and afterward Mate (pronounced mah-tay), a caffeine laden tea that people drink all day long out of ceramic cups and metal straws, or coffee. After a three hour meal of gorging yourself you must have a dessert of something like ice cream or flan, because you've earned it by that point. This lunch/dinner is generally the longest meal of the day. On work days, breakfast is often skipped entirely with people subsisting on mate/coffee and snacks until lunch comes around, which is typically pretty large. There's quite a few people with Italian heritage here so I am told, and this heritage lives on in the form of complicated and delicious meals. I had some awesome classic Italian style pizza on Thursday for CADIC's monthly special lunch.

Skiing is fun

On Sunday I went cross country skiing for the first time. Although I think downhill skiing is more fun, you definitely get a work out going on the flat. It was snowing the entire day but I had brought enough clothes to stay toasty. Later we settled in for lunch, which turned out to be serving after serving of lamb, followed by dessert. Again, a delicious three hour meal. After going out and sledding for a bit we drank hot chocolate, where you dip and stir a chocolate bar into some hot milk. I'm going to have to try that at home next winter.

Panorama of the recreational ski valley just outside of town. Skiing, dog sledding, and snowmobiling all in one place!

Today I got back to work, next thing on the list was to start processing the samples that I had sorted through last week. There's many steps in the processing of bones for stable isotope analysis, but broken down into individual tasks they are simple. First you pick one of the samples, in this case the seal maxillas, and break off a small piece. I have a dremel tool which works like a small power saw, but they can create a lot of bone dust if your not careful. I also realized that I don't have the correct electrical adapter for it so that's out. It's ok since pliers work just as well and create less of a mess. The bones themselves are rather brittle and fragile so it's very easy to snap off small pieces of the right size.

Weighing bits of bone before demineralization. Notice the seal maxilla trying to eat its way through the vial tray.

 I take an initial weight for each bone sample in order to figure out how much collagen (the bendy, cartilage like stuff in bone) each bone contains. Typically, bones are 70% mineral and 30% collagen. However in older bones that have been buried for several thousand years, collagen breaks down. For bones of the age I'm looking at there is usually only about 20% collagen or less. I'll be measuring stable isotopes from collagen since that is what will accurately tell me information about the seal diets. Not to say that bone mineral is not useful. In the future I may drill some teeth for mineral which can provide insight into aspects of the seal's physical environment. Once the bone samples are weighed into vials, I can begin demineralization. That step I'll begin tomorrow.

Until next time, buenas noches my friends. Also, feel free to leave any comments if you'd like to hear about something I haven't talked about. There's plenty more I can write about!

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!

Left - The pathologic specimen, tumor cavity in full view. Right - Example of a modern healthy fur seal skull

Looking up and underneath at seal maxilla #32444 and the comparative skull.

Looking head on at the pathologic skull

Looking straight into the tumor cavity

Bienvenido a Argentina

Buenos Aires from the air

After a long, sleepless overnight flight I arrived in Buenos Aires. Since my connection to Ushuaia required me to travel to another airport in the city, I had to take a bus across town, passing through the downtown area. On the outskirts of town near the international EZE airport there were several fields of people playing soccer, several biking pump tracks, and many trees without leaves. The tree skeletons were the first sign I had that it is winter in the southern hemisphere.

Along the walkway near the Aeroparque

Once I got to the Aeroparque, the domestic airport, I found a nice walkway along the coastline with food trucks selling hamburgers and other meaty sandwiches, a nice relief from all the airport food. The climate is quite nice in Buenos Aires even during the winter, you would be fine just walking in a t-shirt. I spent some time walking around before my next flight and taking in some sights before my next flight.

A restaurant and the sadly unaccessable pier near the Aeroparque

The flight south to Ushuaia was uneventful. That is until the very end of the flight. As we were descending into the airport, the plane starting creaking, the wing was bending more than I would say is comforting, a guy in front of me threw up. You could hardly see anything out the window. We were getting close to the runway when the pilot blasted the engines and we pulled up sharply. He later informed us that he couldn't see the runway, and that we would have to fly in a holding pattern until the weather improved or land at an alternate airport. After circling around above the airport a few times we descended again and made the landing. The entire plane erupted in applause, and rightfully so. The lights on the runway were buried in snow. I've never been more grateful to get off a plane and thank the pilots. Landing on an ice runway with skis was less nerve-wracking than this.

Arriving in Ushuaia. Below and to the right of the light is a human, for scale.

I was welcomed by Pancho, my host professor in Ushuaia. After a quick stop we dropped my baggage at the room I'll be living in for a month, and took a fantastic shower since I hadn't been able to for a few days. Pancho and his wife Angie treated me to a muy muy delicioso dinner. They had fine cuts of beef, pork and lamb with sausage, traditional Argentinian offerings. All in all, an excellent introduction to the city at the end of the world.

The office

This morning I was introduced to many different scientists and students working at CADIC (Centro Austral de Investigaciones Científicas) who work and operate labs in archaeology, biology, geology and other sciences. For my scientist friends who may be interested, there is a huge opportunity for collaboration on many different kinds of projects. I was discussing with Pancho different directions I could take my project, whether I wanted to expand spatio-temporally or work with different organisms and field sites. Luckily for me, the samples I'm interested in working with have been radiocarbon dated, their ontogeny identified (juvenile vs. adult individuals) and sexed. The combination of these characteristics along with dietary information gleaned from stable isotope analysis are extremely useful for not only identifying general ecological information, but about life histories of individuals. Not only that, but in a population of seals that lived and were hunted by humans about 6,000 to 5,000 years ago. Also, I'll have access to large collections of animals from various parts of the food web, including mussels at the base to fish and seabirds at the middle and high trophic levels. Ultimately, I will be able to understand what life was like in Tierra del Fuego from both a holistic perspective and a focused perspective (for the seals, at least.)

More importantly, the view from the office

Until next time, adios amigos!