Estancia Harberton

Estancia Harberton, home of missionary Thomas Bridges and family in 1886. Imported brick by brick from England to Tierra del Fuego. Located east of Ushuaia by 50 km or so.

Yesterday I joined the archaeologist crew to collect some of my own samples and help carry bags of rocks. They were very heavy and my arms are quite tired still. But it was quite a productive day trip! We managed to carry 145 rocks over several kilometers, which will eventually help my fellow graduate student Carmen determine the source of lithic tools that were used by the Yamana. For my own sampling, I took some samples of kelp and some water samples, one of each from a bay exposed to a river mouth and one from the bay facing the Estancia Harberton (pictured above) which does not have a direct freshwater input. I doubt there will be significant differences between the two areas but good to measure extra just in case. The waters of the Beagle Channel are known to be exceptionally fresh compared to ocean waters from other parts of the world, due to the high amount of precipitation and freshwater inputs (from snowmelt and glaciers), but I will find this out and verify this claim personally!

Loading a large bag of rocks to be carried back to the truck.

The purpose of sampling water here is two fold. First I'm interested in differences in the waters of the Beagle Channel and the southern Atlantic/Argentine Sea, specifically to see what differences in water chemistry there might be, especially when it comes to nutrients and trace elements. Different nutrient loads can have an impact on the productivity of food webs, which would in turn have effects on species high in the food chain, like top predators such as fur seals, sea lions, and cetaceans (whales and dolphins). Trace elemental analysis can help me not only differentiate bodies of water, but serve as an independent method that would potentially verify where my fur seals and sea lions spend their time. Trace elements are incorporated into your tissues just like stable isotopes are and can (hopefully) be used a tracer.

A figure showing the interaction of different bodies of water in South America (from  Acha, E. M., et al. Marine fronts at the continental shelves of austral South America: Physical and ecological processes. J. Mar. Syst. 44, 83–105 (2004).) 

The measurement of kelp will serve a similar purpose. Giant kelp, Macrocystis pyrifera, grows around the world, from the coasts of Alaska, New Zealand, Japan, all the way down to Tierra del Fuego, It's a very successful species, one of the fasting growing on the planet (a meter a day in the right conditions) and forms the basis of many highly productive food webs around the world. Constraining the variation between southern Atlantic kelp and Beagle Channel kelp will give me an understanding of what to expect when I compare the stable isotopic values between giant kelp, kelp based fish and ultimately fur seals and sea lions. Fur seals and sea lions might be moving back and forth from open ocean to kelp ecosystems or changing their degree of residency in kelp ecosystems over time so it's important to understand what the kelp ecosystem looks like versus the open ocean.

Soon I leave for the Atlantic Coast, Peninsula Mitre and Bahia Thetis, site of the abandoned sealing operation that ran from 1946 to 1952. Bahia Thetis was formerly known as the Bay of Good Success, I hope it lives up to its name!

Wild horses seen while sampling near Estancia Harberton