Saturday, December 17, 2011
The Hengill region became blanketed in snow much earlier this year than last. The snow has greatly limited our access to our sites. We've tried walking (3 hours one way), skiing (2 hours one way), and earlier we described what happened the last time we used a truck. On Friday, the University of Iceland's Geology department allowed us to rent a couple of snowmobiles and borrow Sveinbjörn, a technician who helped out with the equipment and our reconstruction of our heat exchanger. We were able to get to our sites in 20 minutes on the snow mobiles (pics 1, 2, & 3).
The dam feeding water from stream 7 into the heat exchanger was breached in late November. Before we could return and fix the system the water left in the pipes froze. The heat exchanger was fine.
Friday, we traveled in by snow mobile, rebuilt the dam, and excavated three different sections of iced up pipe. One section of pipe was covered in a meter of snow in places (pic 6). After excavating the pipes we let them thaw in stream 8 (20˚C) and then reattached all the piping (pics 4 & 5). Everything was running smoothly when we left Friday evening.
After we finished up with the heat exchanger we went over to our reference stream to retrieve some dissolved oxygen probes before the holiday break. Normally this is a 45 minute drive in the summer, but it only takes 20 minutes on snow mobiles. I know what I was for Christmas. About 70% of OH2 was covered in a layer of hard packed, wind blown snow (1 to 3 meters worth). Here is Jim trying to pull a probe out of the lower section of OH2. There's really a stream down there. I swear.
Wednesday, December 7, 2011
Hengill has gotten a lot of snow recently. So, for our December sampling we got help accessing our streams from the Hveragerði Rescue Squad. Most Icelandic towns have Rescue Squads. These are all volunteer organizations which help people lost, hurt, or stranded at sea, on land, and on top of glaciers. In their off time, they generously help us get to our field sites. The Hveragerði Rescue Squad has a truck with very wide tires. When the tires are slightly deflated the truck "floats" on the snow like its wearing snowshoes.
Tuesday, December 6, 2011
After a fairly sunny summer, there has been a lot of rain this fall. In November, discharge in many of our streams was approximately 10 times higher than during the summer, although the discharge in some streams has hardly changed. These differences in flow arise because some of our streams drain large watersheds (like stream 14, shown above in Nov and below in July) while others have tiny watersheds and appear to derive almost all of their water from springs (e.g., stream 8). These differences in discharge variability among streams likely translates into large differences in disturbance. Disturbance is known to play an important role in shaping stream food webs and ecosystems.
Below, Wyatt dances while he measures nutrient uptake in stream 14 sometime in July.
Since the summer, we’ve been measuring the magnitude of disturbance in each of our landscape streams. We use super glue to attach tiny pieces of flagging tape to 50 randomly selected rocks in each stream. The photo below shows a transect of flagged rocks in stream 7. The flagged rock at the bottom of the photo has been moved downstream away from the transect.
After three months, we return to each streams and determine whether each rock has moved. In sum, these rock movement measurements give us a metric of the degree of disturbance in each stream.
Wednesday, October 26, 2011
Tuesday, August 16, 2011
In addition to helping out with the July landscape sampling, Adam and I conducted an experiment to examine the influence of temperature on the processes of benthic nutrient uptake and metabolism (see previous blog post). It was fun and challenging to come up with the procedure for sampling these chambers, since they are usually only used for metabolism. At the very end of the summer, Adam and I worked hard analyzing the data for six of the streams that we sampled. I hope to be able to continue analyzing and interpreting at the data in preparation for the NABS science conference next year.
In addition to acquiring tons of great data, we had some time to explore the beautiful country of Iceland. Here is a photo of me scuba diving in a part of the mid-Atlantic rift, which runs through Lake Þingvellir and divides the North American and Eurasian plates. The water was even colder than stream 13 – it was only 3 °C! After the project was completed, our group had a wonderful time up at Lake Myvatn. From there, I traveled around the East Fjords and down along the south coast of the island. This summer was fantastic! Thanks to everyone who made it happen.
Thursday, August 4, 2011
Adam and Brooke collaborated on a project examining patterns of epilithic metabolism and nutrient uptake across a temperature gradient. They incubated tiles in six streams varying in temperature from about 7 ˚C to 22 ˚C. After about month, Adam and Brooke used chambers to measure metabolism and nutrient uptake. Toom-Toom and Weigs (as they are fondly known in Hengill) used YSI probes to measure changes in dissolved oxygen (DO) during a “light” incubation (first picture) and then during a “dark” incubation (second picture). In the third picture Brooke is showing off our improvised battery pack.
Changes in DO during the “light” incubation reflect the balance of primary production and respiration. Dissolved oxygen changes during the “dark” incubation provide a measure of respiration (we assume primary production doesn’t occur in the dark). After the light and dark incubations, Adam and Brooke added stream water spiked with a small amount of nitrogen and phosphorus. They took several water samples over the next few hours to measure the uptake of nutrients by the epilithon. The forth picture shows Adam taking nutrient samples and the last picture shows epilithon from a cold stream greedily sucking up nutrients.
Toom-Toom and Weigs recently completed their projects. They hope to present their results at next summer’s North American Benthological Society meetings.
This shot gives some idea of how the team was spread out across the landscape during many days in July. I took this photo while doing slug additions in stream 9. In the foreground are Jim, Adam and Dan doing the same in stream 7. Further back, Junks is doing a slug in stream 6, while in the distance one can just see Brooke and Wyatt doing their slugs in stream 5. Beautiful! The question now is: can this be done in winter? We'll have to wait and see.
Thursday, July 28, 2011
The beginning of the month marked the arrival of a few fresh faces as Adam and Brooke, two REU students working with us this summer, arrived and jumped right into field work.
<--- Brooke sampling benthic chambers during a nutrient uptake experiment.---
Wednesday, June 29, 2011
We've tested the heat exchanger and it passed with flying colors.
Tuesday, June 28, 2011
Here are some shots of the heat exchanger starting to come together in the Benstead lab. Here, Jon and Chau are getting ready to link up the 72 steel tubes to the manifolds. Note that Philip the Engineer is conspicuously absent for the construction phase...
Tuesday, June 14, 2011
Wednesday, May 18, 2011
Tuesday, March 1, 2011
|Kid in the candy store.|
|Where is Stream 7?|
|Jim and Gisli sampling from 'the hole' in OH2|
|In the rescue team vehicle. .. .good stuff.|
|Rescue team leader from Hveragerdi|
|Jon in the midst of a nutrient slug.|
|A nice view of Hengladalir|
|Lamb testicles, whale blubber, fermented skate, smoked lamb, blood sausage, sheep head. . and more. . .thank you Gisli!|
|Jim looks scared as the lamb testicles arrive. . .|