Interdisciplinary Action of the Day

A cool thing about being part of an interdisciplinary group focused on understanding Polar Environmental Change is that everyone knows I am studying Arctic mosquitoes, so when the ethnobotanist/linguist pulls out an obscure text on lifestyles and languages of the Iglulik Eskimos, they can alert me to scientifically informative passages, such as “Of the lower animal world may be mentioned the mosquito which, in the short summer – from the middle of July to the middle of August – can make life in the open air a torment. The low, swampy land on Southampton Island is said to be particularly bad in this respect; there are fewest mosquitos [sic] in Cockburn Land, although at certain places, for instance round the trading station at Ponds Inlet, they can be extremely annoying.” Therkel Mathiassen, in Material Culture of the Iglulik Eskimos, a report from the Fifth Thule Expedition 1921-1924

Although brief, it’s relevant to what I am studying- the distribution, abundance, and phenology of mosquitoes in the Arctic. I suspect that the humanities literature, especially accounts from historical expeditions, is full of useful references and tidbits of scientific information. Without interdisciplinary collaboration, much of this information would remain elusive.

IGERT POWER. And thanks, Simone.

[Aedes nigripes posing for a photo in front of the Greenland Ice Sheet.]

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Welcome Cohort 4!

This term we welcomed the fourth and final Dartmouth IGERT cohort to our clan. We thought that a great way to welcome them would be to create a scavenger hunt that would take them across Dartmouth campus, finishing with a group dinner with cohorts 1, 2 & 3.

And the scavenger hunt begins….

The scavenger hunt started in the Arctic library and took cohort 4 to various important places across campus: Thayer engineering building, Ross Virginia’s office, to the Steffansson collection at the Rauner Library, and to the new Life Sciences Center.

Cohort 4 completes a task of the scavenger hunt by taking a photo on the green with no feet (or hooves!) on the ground.

The scavenger hunt culminated with a fun dinner with all cohorts present.

Ross Virginia with all of the IGERT cohorts. A great way to kick of the new term!

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Tour de Arctic Lakes

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?

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

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.

High density sea tomato lake.

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.

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.

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

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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