In the morning, we focused on lake ecology. We began with a presentation from Zachary Wood, who told us about the main types of lakes found in Greenland, before heading out to the group´s research site. A “Fault Valley Lake” is the only type of lake not formed by ice. Instead, it is formed along a fault where one side moves, and rain fills the resulting space. It is characteristic of a Fault Valley Lake to have a very steep side, and a large depth. The second type of lake is a “Kettle lake.” A kettle lake is the most common lake in Greenland and is formed when the ice sheets move and a chunk of ice is left behind in the ground. Because the ice melts very slowly, sediment builds up around the edges and the ice pushes down on the soil, making a small, round, shallow indent where rain or the melted ice can stay. The third type of lake is a “Cirque Lake.” The name ´Cirque,’ is from a French word which means arena, or amphitheater, and describes the lake perfectly. Cirque Lakes are formed on the slope of a hill when ice pushes down and carves out the mountainside. There are generally steep hills or cliffs around three sides of the lake. The final type of lake is a “Cryogenic Lake” which is a very shallow lake, so shallow that plants can grow through the middle, is generally the shape of a hexagon, and is common in northern Alaska. These lakes are formed when the active layer of the soil cracks (due to the constant freezing and thawing) and the soil becomes saturated between these cracks, often forming a lake.
We also learned about the different colors a lake can be, and what they mean. A lake’s color depends on the wavelengths (colors) it reflects. If a lake has clear water (a blue appearance), then it absorbs all colors except blue and purple and therefore appears a slightly bluish color. A lake with some organic materials, reflects red through yellow, and absorbs the blue end of the spectrum, appearing a brownish – green color. If a lake is home to a lot of phytoplankton, then it absorbs all light except green and therefore has a very green coloring. The lake we went to was greenish, showing that it had a lot of phytoplankton.
Then we learned about Sea Tomatoes, which are colonies of cyanobacteria that lives in several of the lakes in Greenland. Sea Tomatoes are the topic of Jessica´s research, and, as she explained, are very interesting. They have the capability to photosynthesize, and can nitrogen-fixate. Sea Tomatoes also make several different types of toxins, a liver toxin called microcystin (which is common in lake bacteria) and a neurotoxin called BMAA.
When we got to the lake, Jessica showed us an example of a Sea Tomato, which looks like a round, orange tomato and can be anywhere from the size of a ping pong ball to a large orange. They have the consistency of a grape and have no taste, according to several students who tried a bit (despite the toxins). Then we began collecting Sea Tomatoes, which live about 4-8 feet offshore, measuring and weighing them, and cutting them open to see if any parasites, zooplankton or bugs lived inside.
We each got to take a turn in the kayak as well, and Zach showed us how the radar is used, along with different methods of collecting data. Several members of our group decided to go for a dip, and as several participants reported, “it was cold… but it really wasn’t that cold.”
After lunch, we headed out to meet Ruth Heindel and Phoebe, who are experts on erosion. We learned about wind erosion, which sweeps away the topsoil. We then learned about a method of lichen dating where you can tell how long ago the spot was eroded. Lichen is a symbiotic relationship between algae and fungi, where the fungi provides the structure, and the algae provide the energy through photosynthesis. It grows in a circular shape, each year growing bigger and bigger, and scientists can tell how long the lichen has been growing based on its diameter. Each group then split up and counted and measured 25 different spots of lichen.
Then, we went back to the building to analyze the data we collected, using Excel to find the current rate of erosion (between 1 and 3 cm per year) using the diameter of the lichen, the distance from the edge of the eroded area, and the given equation linking diameter of lichen and age.
Words of the day (Greenlandic, Danish, English and Spanish:
Anori, Vind, Wind, Viento
Taseq, Sø, Lake, Lago
Issoq, Jord, Dirt, Tierra