In this Activity students will simulate aspects of the Antarctic ice ecosystem, and see how simple life forms respond, modeling links between environmental factors and biological responses. Although brine shrimp are different from krill and silverfish, students should recognize the parallels with the work done by the Palmer LTER team.
Objective
Students will conduct a controlled experiment with brine shrimp eggs in order to draw conclusions about this organism's response to variations in light levels and water temperature.
Materials (for each group of 3/4 students)
Please note: as we've suggested in previous Passport to Knowledge field trips, if the materials for any Activity are beyond the resources ordinarily available to you, consider enlisting a local high school science teacher, for whom such simple items are more likely to be available.
Any organism must respond to changes in their environment in order to get food, avoid predators, and successfully breed-in short, to survive. In the Antarctic, the LTER group has confirmed that some of the most important factors are as expected: the seasonal cooling and warming of the continent. But their work in the last few years has also begun to show the precise mechanisms by which the (relatively) hotter/colder cycle works, by affecting the size of the ice-sheet, the time when it appears from year to year, and how it affects the amount of light and dark penetrating down into the ocean. In this experiment, students can observe how brine shrimp react to changes in their environment, which somewhat parallel the above phenomena.
Ensure that students understand brine shrimp are "stand-ins" for the krill they'll see in the videos. Review with students the Krill to Kill? Blackline Master #10, so they understand something of the actual life cycle of krill and the conditions they face.
Procedure
1. Organize class in research teams, hand out Activity 1.1.1 Student Worksheet, "How Do Brine Shrimp React to Physical Stimuli?", review materials list, and lab procedures. Have students complete their hands-on investigation.
2. When all groups have finished their investigations, have research teams share their results and discuss. Were all results the same? What might account for any differences? Which variables were difficult to control?
Referring to the krill data sheet, could students replicate the entire life cycle of krill in the pack ice by freezing brine shrimp in the lab? Why or why not? Explain. Response should go into their assessment portfolios.
Sea ice is easily tracked by satellite and infrared imagery. Link from the LFA 2 Web site to other sites, such as those maintained by the Palmer LTER group, NOAA and NASA, to see how the ice grows and retreats with the seasons.
