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Archive for the ‘Sam Fey’ Category

Kangerlussuaq is peppered with lakes and ponds, extending all the way up to the ice margin. There are many interesting questions to be answered with regard to these lakes – for example, what are the nutrient inputs? How does the water chemistry vary between each? What is the community composition of aquatic plant and animal life? And how might all of the above parameters be influenced by the surrounding vegetation and geology?

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Setting up to take water, sediment, and plankton samples. Photo courtesy C. Vario.

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The crew finds sea tomatoes settled all over the lake sediment. Photo courtesy C. Vario.

To get at some of these questions, Ali, Chelsea, Stephanie and I headed into the field one last time before leaving Greenland. Together, we sampled four lakes between the town of Kangerlussuaq and the ice margin. These lakes are especially interesting because of the orange, spherical balls inhabiting them, known locally as sea tomatoes. These fascinating organisms are a species of colonial cyanobacteria belonging to the genus Nostoc. Lakes here are highly variable in their abundances of sea tomatoes, with some having no visible colonies, and others supporting hundreds to thousands of colonies.

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High density sea tomato lake.

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Sea tomatoes vary in size, with large colonies reaching the size of a softball.

To capture this density gradient, we sampled lakes at four different sea tomato densities, ranging from no visible colonies, to high abundance (estimated to be thousands of colonies). At each lake, we took samples of (1) whole lake water, (2) lake sediment, (3) zooplankton and phytoplankton, and (4) the sea tomatoes.

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Steph tosses the plankton net into the lake to capture zooplankton. Photo courtesy C. Vario.

Back in the lab, I hope to use these samples to better understand the occurrence and distribution of sea tomatoes, including: what are some of the limits to sea tomato dispersal? Lakes with few to no visible sea tomatoes are often situated next to lakes teeming with them; what limits their movement and establishment to certain lakes, but not others? Do high versus low sea tomato lakes show differences in water and sediment nutrient levels? Many species of cyanobacteria, including other species of Nostoc, produce toxins, but we don’t yet know whether or to what extent sea tomatoes in these lakes are releasing toxins into the system. Further, examining the zooplankton will allow us to ask additional questions about the movement of the toxins through the food web and more generally, about the composition of these arctic lake communities.

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Steph and Jess inspect the fresh plankton net catch. Photo courtesy C. Vario.

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Lively zooplankton dart around the sample jar after being caught in the plankton net. Photo courtesy C. Vario.

*Look for updates soon on what we are now learning from these samples!*

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Scientist in Action at Nuuk Basic

This week we had the unique opportunity to visit Nuuk Basic, a low-arctic long-term ecological monitoring station.  The research station is part of the Greenlandic Ecological Monitoring (GEM) program, which also has a station in high-arctic northwest Greenland at Zackenburg.  The goal of the GEM program is to study the effects of climate change on the terrestrial, freshwater, and marine environments of Greenland and more broadly the arctic using “cross-disciplinary” techniques.

Greenland Ecological Monitoring (GEM) program sites

Cross-disciplinary – it is kind of like double narwhalwhat does it mean?

When I think of the term cross-disciplinary, I envision using one set of methodologies (i.e. ecology) to think about and answer questions in a different field (i.e. geology).  Cross-disciplinary may or may not be synonymous with multi-disciplinary, inter-disciplinary, or trans-disciplinary; it may also just be used colloquially as a synonym.   This is one very interesting questions that our Polar Environmental Change IGERT program at Dartmouth College is trying to think about and contribute to the discussion occuring in academia.

Badeso in the foreground (i.e. the lake with Arctic char) and Kobbefjord in the background

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The 2011 IGERT cohort spent one week camping outside of Kangerlussuaq in the same site the 2010 cohort chose last year.  The first things we noticed upon arriving at our campsite were the incredible views of the Russell glacier, the Little Ice Age moraine, and the glacial meltwater lakes.

Google map of the area between the IGERT camp near the Russell glacier and the Kangerlussuaq fjord. Air temperatures drop as you drive up the road from Kangerlussuaq to the IGERT camp and the glacier, perhaps offering a gradient useful for studying climate change and insect outbreaks.

But as a close second we noticed that the woody shrubs at the site were all leafless and brown, and that there were many large Lepidoptera larvae (caterpillars) roaming in search of food.  This place had experienced a recent caterpillar outbreak. The larvae that were left had no more food to eat, and they crawled up our tents and boots or into any warm microclimate.  Northern wheatears and snow buntings came in to camp to eat this easy prey off the tents.  Adult moths also flew around in large numbers and we picked them out of our hair and our coffee.  We identified this Lepidoptera species as Eurois occulta, the Great Gray Dart moth known to defoliate the dwarf birch and grayleaf willow common in Greenland.

Caterpillars ate all of the birch and willow leaves around camp, leaving a brown world.

Eurois occulta larva

Eurois occulta adult

However, the entire landscape was not brown.  Many hillsides with similar aspect and distance from the glacier experienced only moderate levels of herbivory and remained green.  Farther from the glacier, back toward Kangerlussuaq and the fjord, the brown outbreak patches disappeared.  Acting on a hot tip from Mike Avery, a PhD student in Eric Post’s lab at Penn State University, we searched for evidence that caterpillars were attacked by a pathogen – desiccated caterpillar corpses draped in the willow leaves.  We found many of these corpses in non-outbreak areas farther from the glacier but did not see any close to the glacier where air temperatures are much cooler.

Some nearby hillsides, however, suffered only slight defoliation.

Closeup of moderate levels of herbivory.

Carcass of a larva infected by a pathogen.

Why are some hillsides completely brown while others remain green?  This is a big question in ecology, and one possible answer is that caterpillars in defoliated areas lack “top-down” controls by predators such as birds, other arthropods, and pathogens.  The caterpillar immune system can fight off infection by pathogens (fungal or viral) but this defense requires a high protein diet.  In plants much of this protein is RuBisCO, a nitrogen-rich enzyme essential for photosynthesis, and the protein content of leaves is expected to decrease as air temperatures get warmer and the growing season gets longer.  Perhaps caterpillars farther from the glacier had less resistance to pathogens because of lower protein content of leaves, or perhaps there are more natural enemies such as birds or arthropods in warmer areas.  The birch/willow shrub tundra of West Greenland is a great ecosystem to test competing explanations for why insect herbivores sometimes outbreak and how climate change may alter the frequency and intensity of these outbreaks.

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With the greatest effects of climate change expected to be seen in the Arctic, we will likely see major changes in the hydrologic cycle. The lakes in the Kangerlussuaq region of Greenland have unique ecosystems and, because of their great number, play an important role in the surface albedo and local climate of the region.  These lakes are already changing in size and future expansion or contraction of the lake area may result in significant changes in the local water balance, surface albedo, and ecological processes. In order to predict the future changes of these lakes, such as changes in volume, chemical compositions, or ecological processes, we first need to understand the water balance of these lakes and the hydrologic cycle of this region.

There are two main types of lakes around Kangerlussuaq which have different hydrologic regimes. Most of the lakes receive water from precipitation only and because they are in closed basins, lose water primarily through evaporation. The other type of lake is located near the ice sheet and differs from the others by receiving the primary input of water from melting ice, with precipitation playing a lesser role. These inputs and outputs of water are going to be changing as climate change progresses so it is important to understand the current hydrologic cycle before these major shifts occur.

Ben and Sam overlooking meltwater lake

Precipitation fed lakes in Vulgaris Valley

In order to quantify these components of the hydrologic cycle, our group conducted a series of studies on a number of lakes in the Kangerlussuaq region. One of the primary efforts was to collect water samples to be measured for their isotopic composition as the isotopes of water are powerful tools that are used as tracers to understand hydrologic cycle dynamics. In addition, samples were taken to measure the water chemistry, determined the depth of lakes from our boat, identified if lakes were stratified or not, and we used a YSI multiprobe to measure various properties of the water that included temperature, pH, and conductivity. From these measurements, a series of mass balance relationships will be used to best determine the rates of inputs and outputs to these lakes to define a starting point in order to predict future changes.

Sam sampling on dried up lake near camp

The team sampling from boat near the ice sheet

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IGERT's at GISP2 Ice Core borehole

A metal cylinder protrudes from the Greenland Ice Sheet. An IGERT photo opportunity?

Absolutely, considering this metal cylinder changed how humanity views its production of CO2, nitrous oxide, sulfuric and nitric acids, CFC’s and other “greenhouse” gases (U. New Hampshire).

Prior to being a year-round research station, Summit Camp was the drilling site of the Greenland Ice Coring Project (GISP2). Drilled from 1989—1993, GISP2 is the deepest (3053.44 meters) and longest ice core record (>100,000 years) in the northern hemisphere.

The GISP2 ice-core record provides a continuous and detailed record of fluctuations in accumulation and climate variability over central Greenland. The GISP2 ice core, in conjunction with the GRIP deep ice core, revealed that exceptionally large climate changes (more than 20° C warming) can occur over much shorter time periods (5 to 40 years) than previously suspected (Cuffey et al., 1995)

In total, forty-two types of measurements composed the GISP2 deep drilling effort. The borehole, what remains after the conclusion of drilling, is filled with a fluid that keeps the borehole stable/open. The borehole can then be monitored via temperature-logging. The current metal casing may be in need of repair in order to keep the borehole available for future logging. Hopefully the National Science Foundation can find a way to maintain the GISP2 borehole, keeping the historic ice core borehole available for future measurements.

Cuffey, et al., “Large Arctic Temperature Change at the Wisconsin-Holocene Glacial Transition”  Science, Vol. 270, No. 5235, pp. 455-458, Oct. 20th 1995

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What is Fukushima?

In case you’ve been living under a rock or on top of an ice sheet, Fukushima radiation, refers to the release of nuclear radiation from the Fukushima I Nuclear Power Plant in Japan starting on March 11, 2011.

The release of radiation was caused by one of the world’s largest ever recorded earthquakes, a 9.0 magnitude, that struck off the east coast of Japan. The earthquake created a large tsunami up to 133 ft in parts of Japan.  The combination of the huge amount of shaking and the inundation and power of the tsunami wave lead to the eventual meltdown of 3 of 6 reactors at Fukushima I and the release of large amounts of radiation from the power plant (See Wikipedia and the NY Times).

So what does Fukushima have to do with Summit, Greenland?

Ice core scientists use atmospheric events such as major volcanic eruptions to confirm the age of ice cores at specific depths.  Beta radiation from upper atmosphere nuclear weapon testing during the 1950s and 1960s appear in Greenland ice cores (one such core was drilled right here at Summit, GISP2).  Will radiation from the Fukushima disaster be deposited in the snowfall of central Greenland?

Dartmouth’s own Erich Osterberg, Research Assistant Professor in Dartmouth College’s Earth Sciences Department, was recently awarded a NSF Rapid Research and Response (RAPID) grant to study the impacts of the Fukushima Nuclear power plant disaster.  IGERT student here at Summit Camp are assisting with the collection of snow, which will eventually be tested for the presence of cesium, Cs137.

What evidence is there that radiation from Japan got all the way to Summit?

After the Fukushima disaster began, air masses (possibly containing radiation) from multiple different elevations (red=low, blue=medium, green=high) moved eastward over Greenland, between 2 and 3 weeks after the disaster started according to two different sets of meterological data available from NOAA’s Air Resources Laboratory and their HYSPLIT model.

Now that we know what Fukushima is, what is has to do with the Greenland Ice sheet, and how it got here, lets talk about how we collected samples to test if radiation from Fukushima actually accumulated in detectable amounts in the snow pack.

Willy Wonka and the Chocolate Factory version 2.0 – White Umpa Lumpas on Ice

First we shipped three huge ice core boxes full of 45 4L Nalgene bottles from Hanover, NH all the way to Summit with the 109th Air National Guard unit. Additionally, Thomas Overly, one of the IGERTs who recently completed the 1500km traverse from Thule, Greenland to Summit and back again in May and June had left smaller sampling bottles for us to use for the first sampling procedure. The next step was to dig a huge snow pit (7m long x 2m deep x 1.5 m wide – shown below), which contained two of the sampling locations, and one other pit ~100m away (2m long x 2m deep x 1.5m wide), containing the third replicate.

Thomas, Ben, and Ian digging the big pit

Once the pit was dug, we had the immense pleasure of donning white clean suits and gloves (so as not to contaminate the samples – see Sam and I below) – and transforming into snow umpa lumpas.  And FYI wearing straight white was freezing – super high albedo.

Two sampling procedures were conducted at each site.  The first set of samples was for isotopes and anions; 125mL of snow was sampled once from each 5cm layer from the surface to 1m depth (see Sam and I in action below).  Next we used the 4L nalgenes to sample each 10cm layer three times from the surface to 50cm. In addition to sampling once with the 4Ls, we brought the bottles inside, put them into the sink (we were on dish duty so it was no big deal), and melted the snow in bottles.  We then consolidated the water from the different 10cm increments and different sampling locations into one of the three bottles. Once we had two empty containers for each 10cm increment we went back out to the pits and resampled the layers, so as to increase our total amount of water collected.  The huge amounts of water from each layer and pit was needed so as to detect the very low levels of radiation, which may or may not be present in the snow at Summit.

You may ask why we only sampled the top 50cm with the 4L bottles – well the answer is that the annual precipitation at Summit is approximately 60cm, therefore sampling the top 50cm is more than enough to capture the precipitation that may contain the radioactive fallout from Fukushima.

Marcus Welker and Sam Fey digging sampling for Fukushima fallout

Overall the sampling for Fukushima was a huge success.  In addition to our sampling for radioactive fallout, we observed the stratigraphy of the first ~2m, took a firn sample, and conducted permeability and density tests.  Stay tuned for the results of this work.

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[July 18, 2011]

 

On our hike around the Lake Ferguson loop, we started to think about some of our initial hydrology questions. One of the main questions we want to investigate is the change of lake water volume as the hydrologic cycle changes in a shifting climate.

Examining the landscape before the hike

We checked out some of the lakes on the hike and saw some interesting changes in lake height by observing the vegetation changes along the edge of the lake. We also found a lake that dried up entirely.

Sam on the dried up lake bed

Close up of dried up lake bed

We finished up the hike along the beautiful Lake Ferguson. I even took a quick dip!

Lake Ferguson

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