RP13

• Core Practical 13


  Investigate the effects of temperature on the development of organisms (such as seedling growth rate, brine shrimp hatch rates)
• Changes in average temperature have been recorded via use of ice cores, peat bogs, dendrochronology
• Climate change


  Caused by the greenhouse effect - the increase in greenhouse gases such as methane, water vapour etc. in the atmosphere causing increased absorption of infrared light and increasing average temperature
• Climate change has many effects - melting of the polar ice caps, increased incidence of natural disasters etc. - but one of those could be changes to morphology, number and distribution of organisms
• Equipment


  • Brine shrimp egg cysts
  • Sea salt
  • De-chlorinated water
  • Salt water
  • Beakers
  • Water bath
  • Stirring rod
  • Magnifying glass
  • Forceps
  • Pipette
  • Bright light
  • Refrigerator
  • Graph paper
• Method


  1. Place 2g of sea salt into a beaker containing 100 cm of dechlorinated water. Stir with the stirring rod until the salt completely dissolves.

  2. Put some eggs onto a sheet of paper.

  3. Wet a piece of graph paper in salt water. Place it face-down onto the sheet of eggs so it picks up some eggs.

  4. Observe the graph paper under a microscope and count out 40 eggs.

  5. Remove the rest of the eggs/the paper so there are only 40 eggs there.

  6. Place the graph paper upside-down into the beaker and leave for 3 minutes/until all eggs have detached into the water.

  7. Incubate the beaker at a set temperature (between about 5 and 35 degrees Celsius - this mimics the conditions in the wild) for 24 hours.

  8. Remove the beaker from the incubator.

  9. Shine a bright light on the beaker. Any hatched larvae will swim towards the light and can then be removed with a pipette.

  10. Return the beaker to the incubator and repeatedly remove and count hatched larvae.

  11. Repeat all steps at a range of temperatures.
• Treat the shrimps, eggs and larvae responsibly and ethically for the duration of the experiment and release them into salt water when it is completed
• Risks


  • Broken glass - cuts from sharp object
  • Hot liquids - scalding
  • Biohazard - contamination
• Safety precautions


  • Take care when handling glassware; keep away from edge of desk
  • Handle with care; use tongs to remove boiling tubes from water bath; wear eye protection
  • Use disinfectant; wash hands with soap after handling
• Emergency actions


  • Elevate cuts; apply pressure; do not remove glass from wound; seek medical assistance
  • Run burn under cold water; seek medical assistance
  • Seek assistance
• Plot a graph of temperature against hatched larvae
• As the temperature increases

  The number of shrimp hatched increases, up to an optimum of about 25 degrees Celsius
• After the optimum temperature, as temperature increases


  Number of shrimp hatched will decrease
• This indicates that as climate change increases temperature of sea water, the development of brine shrimps will decrease
• The method can be modified to measure the effect of climate change on seedling growth rate
• Optimum temperature for seedlings

  Increase in growth up to an optimum temperature (as rate of photosynthesis increases) and then decrease (as water loss will increase and crenation may occur)
• This indicates that plants are similarly vulnerable to climate change