Brine Shrimp Essay

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Topic 5: On the wild side 17. Describe how to investigate the effects of temperature on the development of organisms (eg seedling growth rate, brine shrimp hatch rates). Procedure You will need: • Brine shrimp egg cysts • 2g sea salt for each treatment • 100cm³ de-chlorinated water for each treatment • 40cm³ beakers (one for each temperature to be tested) • Water baths or incubators (one for each temperature to be investigated) • Stirring rod • Magnifying glass • Pair of forceps • Fine glass pipette • Bright light Experiment: 1. Decide on a range of temperatures from 5°C to 35°C to be tested. 2. Place 2g of sea salt into a 100cm³ beaker. 3. Add 100cm³ of de-chlorinated water and stir until the salt completely dissolves. 4. Label the beaker with sea salt and the temperature at which it will be incubated. 5. Place a tiny pinch of egg cysts onto a large sheet of white paper 6. Wet a piece of graph paper using a few drops of salt water. Dab the paper onto the white sheet to pick up approximately 40 eggs. This will look like a tiny shake of pepper. Use a magnifying glass to count the eggs. Cut the graph paper so that there are exactly 40 eggs. 7. Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of forceps to gently remove the paper, making sure that all the egg cysts have washed off into the water. 8. Repeat steps 2 to 7 for all the temperatures that are to be investigated. 9. If possible replicate the treatments. 10. Incubate the beakers at the appropriate temperatures, controlling exposure to light as far as possible. 11. The next day count the number of hatched larvae in each of the beakers. To do this, place a bright light next to the beaker. Any larvae will swim towards the light. Using a fine glass pipette catch the brine shrimp and place them in a small beaker of salt water.

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