It's pretty obvious that Antarctica's unique climate and environment drive the processes which shape the life and death of the creatures who live here. But what's been happening in the past few years is an increasing understanding of exactly what aspects of the environment seem to have most impact on the food chain and which species thrive or struggle. The data which reveal these patterns aren't seen in majestic icebergs, or images of cute penguins, but in vast strings of numbers detailing myriad, individually inconsequential details about the size and distribution of creatures, temperatures, ice area, and other factors, collected over many years and then "crunched" into meaning.
Charles Darwin once wrote that the secret forces of evolution were "time and death." This Activity, bluntly called "From Data to Death", introduces students to two simplified data sets, supplied by researchers Robin Ross and Bill Fraser, and invites students to investigate the patterns hidden in them. With luck, the original researchers themselves will be looking over students' shoulders with hints and tips!Sidebar: David M. Karl
Here's some background on Robin Ross' krill data (you can find more in the Blackline Masters for this Activity, and on-line): Antarctic krill release many eggs in the ocean, but just like fish, many krill die before they reach adulthood. There's a lot of year-to-year variability in mortality rates, however, and one of the important aspects of the LTER research project is trying to understand exactly what aspects of the environment affect survival of these young krill. "Length frequency distribution", or how often a particular size occurs in the sample of krill collected, is one of the analyses routinely done on the Polar Duke. When measuring a krill, the LTER scientists use the following standard: total length is from the tip of the "rostrum" (the pointy bit between the eyes) and the tip of the "uropods" (near the end of the tail) and is measured in millimeters to two decimal places. Thus, krill measuring between 8.5mm and 20mm were hatched during the previous austral (January to March) summer. The year-to-year length distribution data combined with other environmental data (sea ice variability, weather, Adelie penguin and skua population statistics) provide data sets for scientists to analyze in order to better understand the structure and function of the Antarctic marine ecosystem.
To simulate sampling techniques, students will utilize random selection to collect middle school height data.
Students will analyze, organize and graph given sets of Antarctic data.
Students will go on-line to question the Antarctic researchers, and discuss possible explanations for given sets of Antarctic data.
Ask students to estimate the average height of all the students in their
middle school. Record all guesstimates on chart paper. Then ask students
how they might obtain the data necessary to
measure the average more accurately and objectively. Discuss the difficulties of attempting to sample every student in the school.
Review with students the purposes of LTER research in the Antarctic and the specific data collection techniques used by the krill group (random sampling at specific locations around the Palmer Peninsula, use of bioacoustics, and measuring of krill body lengths). Explain that LTER scientists cannot measure every krill at each location! Instead they use a technique known as random sampling to collect a set of data that represents the total population-they measure the lengths of 100 krill at each location.
Tell students they will use this technique to gather data that represents the distribution of body heights in their school.
Display transparency of krill (Blackline Master #16) on screen. Ask students to estimate the length of a krill in millimeters. Record all measurements on chalkboard; find range of measurements.
Distribute Bill Fraser's data set, which includes krill data along with sea ice extent, length of penguin foraging trips, and the number of breeding pairs. Assign students to small data analysis teams with the following tasks:
Go on-line with questions to Bill Fraser during Program 2, or submit via Researcher Q&A.
Students may enter the data sets into spreadsheet or graphics programs, and create a computer-generated graph or display.
Go on-line via discuss-lfa, to share ideas with other teachers using this Activity.
Research and illustrate the life cycle of krill.