light/dark bottle methods

• Light/dark bottle method

  1. Take a sample of seawater

  2. Measure oxygen concentration, label as "O"

  3. Split sample into two equal parts

  4. Fill one bottle with see-through material, measures photosynthesis and respiration

  5. Fill other bottle with no light, measures only respiration

  6. Lower bottles to original depth for a given time

  7. Retrieve bottles and measure oxygen contents, label as O1 and O2

  8. Calculate rate of primary production using formula: [(O1 - O) + (O - O2)] / time
• Rate of primary production

  Measures how much biomass is fixed by photosynthesis and how much is lost by respiration
• Oxygen levels

  Used as markers for the production/loss of biomass
• The 'time' value is simply the time the bottles have spent underwater