Polar Radar for Ice Sheet Measurements
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Sunday/Monday, January 15 & 16, 2006 Well, this will be the last journal entry. We are scheduled to leave for Christchurch, New Zealand, tomorrow at about 4:30. The weather forecast is good and we expect to have no delays. Yesterday, there was brisk wind most of the day and fog rolled over the mountains. It cleared nicely by evening and the evening was very pleasant. This week in McMurdo it has typically been around 35-40?F in the daytime and around 10-15?F at night. On the 15th, Claude and Jennifer attended a science lecture by Dr. Diane McKnight of the University of Colorado. She talked about �Stream Ecosystems of the McMurdo Dry Valleys.� The streams she discussed are meltwater streams, because the Dry Valleys are a polar desert in terms of precipitation. Less than 10 cm of snow falls per year, so these streams are fed almost exclusively by glaciers. The meltwater streams flow to lakes in the dry valleys and the flow is quite variable. Basically, the water flows quite fast during the melt period and dries up in the drought period when the glaciers are stable. Just 1-2 degrees can make a difference between drought and flood in these streams. To study these streams, scientists use flumes and telemetry to measure the flow into certain lakes on a daily basis. If you are interested in looking at the data, you can find them on the US Geological Survey site as part of the Long Term Ecological Research (LTER) data set (http://huey.colorado.edu/LTER/). Their group is doing research to determine the linkages between glaciers, soils, streams, and lakes and the living organisms in these habitats. The organisms that live in the streams are algae and diatoms. Dr. McKnight noted that there are two main kinds of algae, orange and black, and these form thick mats. There are many different species represented, though both orange and black algae are made up of cyanobacteria. The black algae which lie along the edges of the streams appear to be more adapted to extreme changes. During times of drought, these mats seem to become almost freeze-dried (very crumbly and dead-looking), but in times when water is available they seem to revive and grow. She said that they had diverted water to one area where they were pretty sure no water had been for 20 years, and the black algae that was freeze-dried there began to grow immediately. The researchers were also interested to find that diatoms were present in all the mats. They saw 40 species, but 18 of those are found only in Antarctica. The number of these diatoms are correlated with the water flow, being more abundant in low flow years. You can see micro-photos of these different diatoms at http://huey.colorado.edu/diatoms/about/index.php (take the Taxa menu to see the photos). They are quite beautiful little one-celled organisms. Certain features of the algae mats help them survive through both flood and drought. For example: a) the mats help retain water and nutrients around them by interacting with the soil; b) the mats begin growing within 10-15 minutes of water flow beginning; c)the stream habitat is warmer than the surrounding soil; and d) fast flow that scours the mats does not destroy them; they are able to regrow. Things that really help the mats in time of floods are: a) the stream beds are made of closely spaced rocks wedged together (stone pavement); and b) even a little water spreads out across the whole stream channel. It is also interesting that when water flows through a stream with lots of mats, it has very few nutrients left when it reaches the lake. Apparently the mats take up almost all of the available nutrients. Pannir and Claude did some last minute paperwork and went to the out-briefing yesterday. It was again reiterated how much our researchers appreciated the fine work of the WAIS support team, especially Dave Anderson and Dave Zastrow. Otherwise, the team has been resting, catching up on paperwork, buying souvenirs, packing and taking photographs. We are all eager to be home and look forward to seeing our friends and family. NOTE: This was the entire journal entry, not just page 1. |
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