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Archive for the ‘Lee Corbett’ Category

The fieldwork is done and now the time comes for the next phase of the process… proposal writing! This summer, I spent the month of July in Thule, northwestern Greenland (you can access my older posts here). I sampled large, glacially-transported boulders for cosmogenic dating as well as marine shells for radiocarbon dating. Now, my task is to obtain the funds to support the analytical costs of processing and measuring the samples.

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View towards Wolstenholme Fjord and North Ice Cap in Thule. A spectacular area!

The goal of this work is to unravel the landscape history of the Thule area. In particular, I am interested in how this complex landscape has evolved over both space and time. After spending three field seasons in Thule, I’ve had ample opportunity to observe the landscape and have identified two different units of glacial sediment that are in separate, but adjacent, areas. For each of these sedimentary units, I will explore the following questions:

1.) How old are the sediments? Were they deposited during the most recent glacial period, or are they a product of an older glaciation?

2.) What is the surface history of the sediments? How long have they been exposed, and do they record times of burial by non-erosive glacial ice?

3.) How erosive was the glacial ice that covered the landscape? Was it an effective agent of change, or was it non-erosive and capable of preserving a relict surface?

4.) What body of glacial ice deposited the sediments? Were they deposited by the Greenland Ice Sheet or by a small outlet glacier during a subsequent re-advance?

33. Favorite moraine

A gorgeous (and very large) glacial moraine near Thule. How old was the ice advance that deposited this moraine?? Hopefully I’ll be able to answer that question later this year!

Through my exploration of these questions, I will address not only the history of the Thule area, but also fundamental questions about the landscape evolution processes at play. Because the area around Thule is complex both spatially and temporally, it provides an ideal opportunity to study a wide range of processes that drive landscape evolution at high latitudes.

The process of writing this proposal has been a very valuable learning experience for me. It has encouraged me to think about the larger significance of my work; in essence, taking my work from a “postage stamp” project (i.e. one that addresses a small, specific area) to a larger and more relevant project addressing ideas that are widely transferable to other areas.

I look forwards to learning more about high-latitude landscape evolution over the coming year!

28. Secret Place

Panoramic view across the Thule landscape, looking towards Wolstenholme Fjord (photo courtesy of my fabulous field assistant Everett Lasher).

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During the 2012 IGERT Field Seminar in Greenland, the all-female cohort 3 was introduced to this promotional video, put out by the European Commission as a part of a campaign to inspire more young women to get involved in science.

The controversial video has since been taken off the European Commission campaign website, but not before sparking some lively debate.  The discussion in Greenland amongst cohort 3 about the video and the role of women in science inspired us to make our own version of Science: It’s a girl thing!.

And so we proudly present:  Science in Greenland: It’s a Girl Thing

What do you think about the European Commission video and our take on women in science?  Despite the controversy surrounding the video, the European Commission has a really cool website for their Science: It’s a girl thing!  campaign.  Check it out: http://science-girl-thing.eu/en.

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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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An interesting part of the field course for me has been learning about topics that are not part of my primary discipline.  While Jess and Chelsea are well versed in the area of ecology Ali, Lee and I are newcomers to the field.  Throughout our week camping we learned a few principles of ecology including the brown and green food webs and biodiversity.  Learning new material while immersed in Greenlandic tundra was an amazing hands-on experience that I’m sure I will never forget.  In the following, I will go into greater detail about the ecology we learned.

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Exploring the tundra around camp

The Brown and Green Food Webs

The green food web is the food web that I automatically think of when I hear the term.  It consists of plants and the animals that eat them and makes up about 10% of the total biomass.  Two of the keystone species in Western Greenland are dwarf birch (Betula nana) and the willow (Salix glouca).

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Photo of Betula nana

Some of the other species that one frequently sees in the Greenlandic tundra are the blueberry, musk ox, caribou, arctic fox, arctic hairs, and various grasses and sedges.  Another fun species that Matt showed us is the Dryas integrafolia a close relative to the species whose pollen is found in lake cores from the cold Younger, Older, and Oldest Dryas periods.

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Photo of Dryas integrafolia

The brown or decomposer food web consists of dead plants and animals and the various organsims that decompose them.  The brown food web makes up the other 90% of total biomass.  The brown food web recycles nutrients and makes them available for the organisms of the green food web to utilize.

Biodiversity of the Arctic

To develop a better understanding of the term biodiversity we set out from camp and hiked up a hill relatively close to the edge of the ice.  Once there, we all spread out and found a one meter by one meter patch of land to exam.  The purpose of our close examination of such a small area was to count as many different types of plants that we could see.  I saw 12 different types of plants in my plot including but not limited to blueberries (Vaccinium uligonosum), dwarf birch (Betula nana), pussy willow (Salix glouca), one mushroom, three flowering plants, two types of lichen and some moss.

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Two flowers from my plot

Once everyone had totaled up all the plant life they saw in their plot we gathered back together to compare notes.  The average number of species identified by each person in the group was 11.2.  At this point Matt Ayres told us that he has conducted this same experiment multiple times in the high altitude regions of Costa Rica and the average number of species seen by that group was only 9.4.  What was going on?

Isn’t it true that the tropics have the highest diversity on the planet?  Could the tundra really have more diversity?  The answers to these questions come in learning about alpha and beta diversity.  Alpha diversity is a measure of the average number of species in a given area from multiple plots while beta diversity is a measure of total species found in all of the plots examined.  So while the Greenlandic tundra was higher than the Costa Rican highlands in alpha diversity it is significantly lower in beta diversity; ie. the total number of species present in the Arctic tundra is significantly lower than the  total number of species found in the highlands of Costa Rica.

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Jess and Ross examining the species present on the hillside with an awesome view of the ice sheet.

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As someone who studies glaciers, I associate the Polar Regions with blue glacier ice and incomprehensibly large, flat, white expanses.  The “Arctic” does not conjure images of anything living, with the exception of the people who live on the rare spots of ice-free land, the mosquitoes that I’m always grateful to escape once on the ice itself, and the polar bears which, in my experience so far, have been only an abstract threat.  (Last year when Lee Corbett, Erich Osterberg, Eric Lutz, and I were in Thule, three bears wandered onto the Air Force Base, but operations quickly called a lockdown.  No one was allowed outside until the threat was “removed.”)

The Arctic, I learned last week, is teeming with wildlife, much of it barely visible (if that) to the human eye or covertly thriving in dense vegetation.  We spent two separate modules on organismal biology, the first in aquatic ecology under the tutelage of expert IGERT fellow Jess and the second in population ecology and herbivory with Matt Ayres.

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Jess teaching the cohort about Arctic aquatic ecology. (Photo: Giese)

Jess’ classroom was a lake adjacent to the ice sheet margin, and her zeal about both the location and the organisms we found engendered excitement among the biologists and non-biologists alike.  She talked to us about the aquatic food web and thermal lake stratification, describing that lakes typically have three layers: the epilimnion (surface layer), metalimnion (middle layer, AKA thermocline), and hypolimnion (bottom layer) that vary by density.  She then had us see what we could catch in nets along the lake edge.  We put on comically large waders; scooped up water, slime, and small plants; and dumped our findings into plastic buckets to see what was moving.

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Students examine their findings from the edge of the lake. (Photo: Ayres)

One of the most ubiquitous organisms we found was the diving beetle, Colymbetes dolabratus, the mosquito’s greatest enemy (I liked this thing instantly when I heard that).  We found it both in adult form and in larva stage, which I was surprised to learn was even larger.  Other notable findings were Chironomids, midges whose eyes and internal features we could see with a hand lens or macroscope once pipetted onto slides.  Some of them were even red because their blood was oxygenated.  We could see their guts filled with food, which they frequently passed.  Their circus-like, rapid flipping movement impressed those of us who had never seen such a thing before!  Apparently, these creatures, which looked a lot like worms to me, will turn into flies someday.

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Chironomid larvae. (Photo: Giese)

Other organisms we collected included ubiquitous mites, zooplankton-like Daphnia, fairy shrimp, and cyanobacteria (one of which closely resembled Gloeotrichia, a species Jess and lab her labmates study back in the Upper Valley!).  Watch for upcoming posts on the shrimp and cyanobacteria from Chelsea and Jess, respectively.

Our specimen collection didn’t end with the near-shore ecology; an inflatable boat took us out into the center of the lake to collect profiles of temperature, conductivity, pH, and dissolved oxygen.  Unfortunately, the high winds precluded us from keeping the boat in a single spot, and they led to so much mixing that the multiprobe readings reflected zero stratification.  Nevertheless, the boat trip was instructive for the non-aquatic ecologists in terms of providing a sense of typical measurements.  A net we dragged behind the boat did yield some interesting finds; Jess bottled up the zooplankton from the lake center to take back to Hanover and examine in more detail.

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Ali, Steph, and Jess lowering the plankton net from the Zodiak boat. (Photo: Ayres)

Water isn’t the only home of Arctic animals, and we spent part of the next day searching for organisms that live on land.  We had already established that our environment supported only 5 mammals—musk ox, caribou, Arctic fox, Arctic hare, and humans—most of which are vegetarians.  But it turns out that they’re not the only herbivores in the tundra!

Matt brought us out into a vegetated field and showed us to how to find the smaller herbivores, which make up in cumulative biomass what they lack in individual size.  We were looking specifically for caterpillars, which had a huge population boom last year.  We heard stories from IGERT cohort II about how these creatures were all over their tents and how it was difficult to walk without stepping on them!  We hadn’t seen any caterpillars yet, but the abundance of overgrazed (i.e. dead) Betula nana was evidence that cohort II hadn’t been exaggerating.

We marched through the vegetation, swinging wildly at the leaves with our nets.


Lee catching bugs in the tundra. (Photo: Corbett)

We then examined our collection…and here began the fun part.  Before the bugs scampered or flew away, we had to catch them by sucking them into a sample bottle (a process called aspiration).  Because there’s a screen between the mouth tube and the sample bottle, it is impossible to have a critter end up in your mouth, but it still took some of us a little while to get used to.


Matt demonstrating the aspiration technique. (Photo: Giese)

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Lee, Steph, and Chelsea collected these insects.  Note the caterpillars in the lower left, stuck together with spider web. (Photo: Corbett)

We found surprisingly few caterpillars; Jess and I found a rough total of five in eight net sweeps.  Instead of caterpillars, spiders appeared to comprise the majority of small creatures in the tundra vegetation.  But this begged a question: since spiders are not eating the plants, what are they eating?  We came up with a few hypotheses, the most promising of which seemed to be that they were eating each other (I didn’t know spiders could be cannibals).  Isotope analysis back in Hanover would tell us for sure; because organisms preferentially excrete the lighter form of nitrogen (N-14), heavier nitrogen (N-15) builds up in tissues.  This means that the primary producers (plant-eaters) have relatively low levels of heavy nitrogen while animals farther up the food chain have increasing concentrations of it.  We’d expect all organisms at the same “trophic level” to have about the same concentrations, but if the spiders are eating each other, there will be greater variation than normally expected (since they’re eating each other as well as below their trophic level).  Little did I know that isotopes could tell us about spider diets as well as past climates and glacial extents!

After the insect and spider lesson, we ventured over to the ice sheet to explore two different parts of its margin.  But I returned to the ice with a much greater appreciation of the myriad of dynamic systems at work on the world’s largest island.

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Aluu!

Greetings once again – what a week we IGERTs have had! Our communication has been limited the past week as we’ve been immersed in our latest adventure, 5 nights of camping at the ice margin! We’ve now arrived back in Kangerlussuaq, where we’ll spend a couple days re-grouping before our flight on Monday to the capital city, Nuuk.

Until then, we thought we’d give you a little recap on how we spent our days on this past camping excursion!

Saturday, July 28

Goodbye Kangerlussuaq: Saturday morning we piled our personal packs, tubs of food, shovels, bug nets, microscopes, soil drill and inflatable zodiac boat into the back of two diesel trucks, and we started our journey up the long, winding dirt road to the ice margin!

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Admiring the view of Long Lake. Photo courtesy M. Ayres.

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Long Lake, en route to our campsite. Photo courtesy M. Ayres.

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The group hikes out to one of Julia’s field sites along the edge of Long Lake. Photo courtesy M. Ayres.

Our first stop was a visit to the field site where fellow IGERT student, Julia Bradley-Cook, is currently conducting research on the effects of factors such as moisture and vegetation type on soil respiration.

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Julia demonstrates to the group how she and field assistant and Dartmouth graduate, Courtney Hammond, have been using an special infared gas analyzer, or IRGA, to measure soil respiration. Photo courtesy M. Ayres.

After this, we pulled off the road in awe of the scenery at a site known as Sea Horse Lake. We were pleased to discover that this backdrop of interconnected, glacially fed lakes and rolling moraines was in fact our campsite!

Thanks to the amazing work of the KISS and CPS (CH2M HILL Polar Services) staff, in addition to our personal tents, our camp was complete with  warm, wind-resistant Arctic oven tents – so we had one designated kitchen tent, and one which we outfitted with microscopes, text books, and a whiteboard as our laboratory/classroom!

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View of campsite by Sea Horse Lake. Not a bad place to call home. Photo courtesy M. Ayres.

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Our kitchen tent, with menu featuring the meal of the evening.

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Classroom tent, about to be used to identify aquatic organisms.

Sunday, July 29

Soils galore: After a hearty breakfast of oatmeal, dried fruit, and French-pressed coffee, we headed to the moraines behind our camping site, where we got down and dirty in the tundra soil. Our resident soil experts, Chelsea and Julia, taught us how to takes soil cores, dig pits, interpret soil layers, and – thanks to Chelsea’s powerful auger and her professional drilling skills – even experienced drilling into the permafrost!

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Chelsea and Steph steady the auger into place as they prepare to take a soil core. Photo courtesy M. Ayres.

Working as a team, the group spent the day collecting soil cores from 10 different sites. We took turns drilling, digging, measuring vegetation, sifting, weighing, and collecting soil layers, which they will take back to the lab at Dartmouth to ask questions about the biochemistry of the different soil layers, and carbon storage of the tundra.

Monday, July 30

Arctic limnology: This morning, we rolled up the road about 10 minutes to the beautiful setting for two small lakes. Here we pumped up our inflatable zodiac and donned our waders to study the plants and animals living in these arctic lakes. Battling the extreme winds that day made taking plankton samples and water chemistry measurements from the boat quite an epic journey! But we couldn’t have asked for a better backdrop. And we found some exciting species, which we will be sure to blog about in more detail soon.

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The zodiac team uses a multiparameter probe to take water chemistry measurements, such as temperature, pH, conductivity, and dissolved oxygen. Photo courtesy M. Ayres.

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Jess, Steph, and Ali paddle back in to shore. Photo courtesy M. Ayres.

Tuesday, July 31

Edge of the ice: After some seriously stellar discussions led by our very own Lee and Ali on glaciology and glacial geomorphology, we spent Tuesday hiking and exploring the landscape at ice margin. Walking through the moraine rubble we reached the ice edge, where we could actually see the transition from sediment, to films of sediment frozen in the ice, finally to solid ice extending as far as the eye could see. The features were amazing – ranging from quickly moving meltwater resembling wild winding ice luges, to deep murky holes of flowing water called moulins, which reached indeterminate depths.

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Lee and Ali prepare the group for the day by describing the physics of glacial movements and the many ways in which they shape the landscape. Photo courtesy M. Ayres.

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The group treks to the ice edge. Photo courtesy M. Ayres.

Wednesday, Aug 1

Spiders, calving, and Jerry Garcia: For our last full day, we started by delving into theoretical population ecology, and then applying it to the field by examining local insect populations on our way to the Russell Glacier. We all practiced proper sweep netting technique to catch a variety of insects, which we then aspirated into jars to examine under the microscope later. What a boom we found in the spider population since last year – more on this later!

We stopped once more along the way through what is known as Vulgaris Valley after the aquatic plant found in the ponds there, Hiparus Vulgaris. Here we discussed the effects of factors like temperature, landscape morphology, moisture, and organisms on soil formation, carbon storage, and how these processes connect to the global carbon budget.

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The group discusses factors affecting soil formation, such as temperature, moisture, and relief. Photo courtesy M. Ayres.

We then hiked to the edge of the Russell Glacier, where truck-sized blocks of ice regularly break off and plummet into the icy waters below, a process known as calving. With front row seats and icy wind stinging our faces, we were all humbled by the magnitude of this active material. It was a show we will never forget.

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The group settles in for a million dollar view.

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A tiny IGERT-er perches to give a sense of scale. Photo courtesy S. Gregory.

Finally, we concluded the evening with an annual commemorative IGERT procession to the top of the Sea Horse moraine. Here, we marveled at the panorama of ice sheet views, and paid tribute to the late, great renaissance music man, Jerry Garcia. Happy 70th , Jerry, all the way from Greenland!

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The moon made a special appearance two days in a row. We’re pretty sure it was for Jerry. Photo courtesy M. Ayres.

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Since returning from Summit, we have had some time to transition into the next exciting phase of our trip here in Greenland: Arctic Ecology

We began our explorations by heading into our own backyard, that is, the valleys and lakes around Kangerlussuaq. Led by Ross Virginia and Matt Ayers, we headed to a couple sites about 5-10 miles out of town, where we familiarized ourselves with some of common local flora.

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The group lines up to practice proper binocular technique. As we were adjusting our diopters, Stephanie spotted two Muskoxen across the river! Photo courtesy M. Ayres.

We quickly became acquainted with some of the major players, or foundation species, in this ecosystem. One of the most abundant species we noticed was a low, shrubby plant called Northern Willow (Salix glauca). They have oblong leaves about 4-6cm long and these plants are dioecious, indicating that each plant is either male or female. These guys were easy to recognize as they produce small clusters of flowers, called catkins, which appear as fuzzy cylindrical stems.

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Northern Willow (Salix glauca)- note the distinguishing white flower clusters, called catkins. Photo courtesy M. Ayres.

Our next common heath plant was slightly smaller, with rounded leaves, and closer to the ground than the Willow, called the Dwarf Birch (Betula nana).  As we walked around, it was clear that Willow and Birch were the two dominant woody species in this landscape.

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Dwarf Birch (Betula nana). Photo courtesy A. Giese.

Other common plants in the area included the bright green, highly branched Field Horsetail (Equisetum arvense), and the beautiful blue Arctic Bellflower (Campanula uniflora).

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Field Horsetail (Equisetum arvense). Photo Courtesy A. Giese.

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Arctic Bellflower (Campanula uniflora).

We’ve also learned the calls and visual markers of the most common birds in this area, including the bright flash of white rump distinguishing the Wheatear (Oenanthe oenanthe), and the red forehead and lightly rosey breast of the Common Redpoll (Carduelis flammea). We’ve also become WELL acquainted with the loud nasal honks and squawks of the ravenous Ravens that guard our dumpster. Species biodiversity in the Arctic is quite low compared with ecosystems that have more tolerable abiotic conditions, less geographic isolation, and more complex food webs. So one of the most satisfying things about working here is how quickly we can have a handle on identifying species!

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Lee takes the lead digging a pit through the sandy dunes in search of key morphological features, such as the sticky root sheaths and small white root mycorrhizae. Photo courtesy A. Giese.

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Ross describes the change in composition and organic matter as go deeper through the soil layers. Photo courtesy M. Ayres.

Next, we tested our reflexes and dexterity through catching fish with our bare hands (yes, we all succeeded!), after which Matt proceeded to shock, amaze, (and test our gag reflexes) as he carefully sliced open the bellies of the Sticklebacks to reveal the slender, pink, squirming parasites living inside. Almost the entire Stickleback population in this lake is infected by this flatworm, observable by the large, distended abdomens displayed by these parasitized fish. The biology of these Schistocephalus worms are fascinating – Stickleback are actually just one of three different hosts necessary to complete their life cycle! In fact, these parasites take full advantage of the food web: they start by infecting zooplankton in the water, are then passed onto a planktivorous fish host (like the Stickleback), and are eventually snapped up and passed into their final host stage, a bird!

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The group gathers around as Matt describes what we are about to observe living inside the abdomens of the tiny Sticklebacks we have just caught. Photo courtesy M. Ayres.

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Sticklebacks and the parasitic Schistocephalus worms thriving inside them. Photo courtesy C. Vario.

But perhaps one of highlights of our adventures thus far…has been meeting infamous sea tomatoes firsthand! At the end of the day, Ross and Matt took us to one of the highest sea tomato abundance lakes in the area, and it blew away all of our expectations. These orange-to-brownish gelatinous spheres are actually colonies of cyanobacteria of the genus Nostoc. Cyanobacteria have a fascinating and unique biology, including the ability to execute three different complex metabolic processes, that is photosynthesize, respire, and fix atmospheric nitrogen! However, while this particular lake bed is covered in sea tomatoes, neighboring lakes appear to have little to none at all. Are they dispersal limited? Nutrient limited? This remains one of the biggest mysteries surrounding their abundance and distribution in this area…and one which we are hoping to tackle as we brainstorm these next couple weeks!

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Sea tomatoes clustered around the edge of the lake.

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Most of the sea tomatoes we found occurred as individual spheres, but occasionally we found them as multiple fused together. Photo courtesy A. Giese.

Last (but certainly not least), we used our investigative power to assess the effectiveness of chocolate cake on happiness and satiation in Arctic scientists. Results – it is highly effective!

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Happy Birthday, Stephanie!!

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