Students will collect chemical, physical, and biological data from a local lake throughout the year. These data will be contrasted with parallel data from an ice-covered lake in the Dry Valleys. They will explore the differences between their local environment and a perennially ice covered fresh water lake in the Dry Valleys, Antarctica.
Visit the LTER web site to discover the myriad of research projects being done this field season. Later, you may want your students to view the site. Together you can share the applications of their procedures and contrast any differences in the environments.
Become familiar with the LTER data sets (http://huey.colorado.edu/LTER/data.html). There is a wealth of meteorological, limnological, geographical, etc. data available. Locate the data sets that will be used for comparison with your students.
Locate an appropriate, safe field location for your students to visit and sample water. This may be a creek, lake, drainage ditch, or stream. Alternatively, sample a sufficient quantity of water for your students and bring the water to class in an insulated container to conserve temperature. You may want to test distilled water to use as a control. (distilled water may have a low pH due to carbonic acid)
The students also can acquire a water sample from their local neighborhood and bring it to class. As a class, discuss what parameters are appropriate. The students should not sample tap water. They should sample in a safe location. Have them appropriately label the sample.
Engagement and Exploration (Teaching Sequence)
Ask the students to share their thoughts on what the water quality is in their local environment. Record their thoughts on a wall chart.
What lives in the local lakes and streams? What do the organisms need to live? What might the temperature be? Is it constant through the day? The year? What about the salinity? The oxygen level? The pH?
These journal pages provide the flavor of the lake system in the Dry Valleys. What might the conditions be in the fresh water lakes in Antarctica (pH, oxygen, temperature, etc.)? Record their thoughts on a wall chart.
What are the environmental conditions in Antarctica? What may live in these lakes?
In the Dry Valleys of Antarctica, some of the lakes are perennial ice covered. How might ice cover influence the lake conditions? Record their thoughts on a wall chart.
Some of the students may not know what "perennial" means. Perhaps prompt them by asking when "annual" flowers bloom? What about "perennial" flowers?
In your area, perhaps there are lakes that freeze each winter. What are the conditions in the lake under the ice?
On the dry valley lakes, the ice cover averages 3 to 4 meters thick. Very little light penetrates the ice. At 12 meters below the ice surface, the depth at which phytoplankton are found, only 1% of the available light penetrates the ice! This ice cover prevents the atmosphere from mixing with the water. There are no waves or water currents at the water surface. There is no atmospheric gas (air) exchange or mixing with the waters. There is no easy way for gas (such as oxygen or carbon dioxide) to escape from the water into the atmosphere*. There is no rain water falling into the lake. No animals can drink from the lakes (...in the Dry Valleys there are no vertebrates except for human researchers and mummified seals).
* as the ice sublimates (changes from the frozen state to the gaseous state - the process where ice cubes in a frost-free-freezer get smaller) gases are released to the atmosphere. This process of gas release from the lake, is very slow. Some microbial mat from the lake bottom is also trapped in lake ice and moves toward the surface to be released into the wind and dispursed throughout the valleys.
How might the lakes in Antarctica be different from or similar to the local lakes?
What about temperature? Organisms? Recreational use? Ask the students to think about human impacts and their impressions of the complexity of the two ecosystems. What organisms do they think make up the different ecosystems?
How might they determine if their predictions are correct?
Explain that they will be collecting data from a local system (or analyzing water, if they will not collect it themselves).
They will analyze Dry Valley lake data (Lake Hoare) that are posted on the web (specific sites listed below).
Have the student groups visit to the Long Term Ecological Research website and examine the Dry Valleys data sets (http://huey.colorado.edu/LTER/data.html data sets). What data may be comparable to information they can collect in their local system?
For their own lake system, ask the students how they will design their experiment.
What are the types of questions that they wish to ask? How much data do they want to collect. For how long? Do they need replicate samples? Why or why not? How will they record the data? How will they display them? What types of comparisons will they undertake between the two ecosystems?
Set out test kits so that the student groups can access the needed materials. Provide the students with the procedure sheets appropriate to the data the students will collect.
Ask the students to read the procedures. Demonstrate the use of the equipment and allow the students to work with the equipment until they are comfortable. You can learn how to doeach test using tap water or distilled water.
I will e-mail our lab sheet to you Steph
Notes to teachers on how the analyses are conducted - needed.
Elaboration (Polar Applications)
Students should agree on a common data table with all parameters available. A possible template is available if you wish to use it.
*** If a field trip is taken, it is important to document the depth at which water is sampled. For the Lake Hoare study, water is sampled every two meters up to a depth of 40 meters. You may wish to take samples from at least two different depths. With portable equipment like the CBL units, or field test kits like those from Hach, test the water immediately after collecting it. If there is no easily available water and you absolutely can not get your students to a testing site, collect some water yourself from several depths at the lake of your choice on the day of the lab and bring it to school. It is important to keep the water at a constant temperature to maintain the dissolved oxygen and water temperature accuracy. An ice chest or cooler works well. This is sometimes problematic, but may be better than no lab at all. Go to the Lake Hoare (http://huey.colorado.edu/LTER/lakedata.html data sets) and download the appropriate data sets for comparison to the parameters your students are measuring in the local lake system)
Evaluate / Class Discussion
Directly from the LTER web site...
Why is it necessary to conduct long-term ecological research on the McMurdo Dry Valleys of Antarctica? To summarize from the McMurdo LTER Site Review Committee's January 1997 report, "the McMurdo LTER project is working on an incredible system for ecological study. It is not just a unique area, but more importantly, it exists at one end of the arid and cold spectra of terrestrial ecosystmes." All ecosystems are dependent upon liquid water and shaped to varying degrees by climate and material transport, but nowhere is this more apparent than in the McMurdo Dry Valleys. In very few places on this planet are there environments where minor changes in climate so dramatically affect the capabilities of organisms to grow and reproduce. Indeed, the data being collected by the LTER indicate that the dry valleys are very sensitive to small variations in solar radiation and temperature and that this site may well be an important natural regional-scale laboratory for studying responses to human alterations of climate. While the Antarctic ice sheets respond to climate change on the order of thousands of years, the glaciers, streams and ice-covered lakes in the McMurdo Dry Valleys respond to change almost immediately. Thus, it is in the McMurdo Dry Valleys that the first effects of climate change in Antarctica should be observed.
During the 1996-97 field season, the field team based operations at the Lake Hoare field camp while collecting samples and conducting experiments on the glaciers, streams, soils and lakes in the Taylor Valley. Types of investigations conducted included: 1)glacial hydrology studies on the Commonwealth, Canada, Taylor, Howard, Hughes and Suess glaciers, 2) stream gauging, collection of water samples and biological studies of streams in the Lake Fryxell, Hoare, Vanda and Bonney basins, 3) studies of planktonic, sediment and ice-associated communities in Lakes Fryxell, Hoare, Vida, Bonney and Joyce, 4) limnological studies of benthic microbial-mat communities and sediments in Lakes Fryxell, Hoare, and Joyce using SCUBA, 5) soil ecosystem studies near Lakes Hoare and Bonney and 6) maintenance and upgrades of meteorological stations and submerged sensor arrays within Taylor, Wright and Victoria Valleys.
taken from http://huey.colorado.edu/LTER/project.html
Engagement discussions may take one 55 minute class period.
Water quality tests will take one 55 minute class period. If you need to take a field trip to get to a local body of water, you need to judge the amount of time required. You may have each student group make all of the tests on the lake, or you may want to have different lab groups responsible for specific tests and share their data. Students should also document environmental conditions, flora and fauna, evidence of human impact and weather .
Testing primary productivity will take two lab days and must use lake water and not tap water.
This activity can be done with or without the primary productivity.
Sharing data and making data tables may take half of a class period.
Comparing student data with that from Lake Hoare in small groups may take one 55 minute class period but could take longer depending on the interest of the students in pursuing other questions about the ecosystem found in the dry valley. Students should access the web to find the data on Lake Hoare in Taylor Valley, Southern Victorialand, Antarctica. If you do not have web access for your students, you can download and provide copies for students. However, the web site also provides photos of the lake. My web page has photos of the lake as well as photos of doing some of the data collection.
See links to the LTER web site http://lternet.edu/
Project Green water quality testing
Access Excellence web site with activities to go http://www.gene.com/ae/
Life on Mars? Video. Discovery Channel School - PO Box 970, Oxon Hill, MD, 20750-0970, 1-888-892-3484, $29.95.
Student Reproducible Masters
Reproducible Master 1
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