Primary Production

1/2 of total photosynthesis occurs in the ocean*

Primary production is important to study because it is the base of the food web

Carbon Cycle

  • Photosynthesis takes up CO2 to make organic carbon molecules of the phytoplankton cell (algae)
  • The Global Carbon cycle is closely related to the Global Warming cycle
  • Respiration produces CO2 gas from organisms
Global Carbon Cycle
  • Photosynthesis produces oxygen
  • 1/2 oxygen comes from ocean

Section II: Requirements for Growth

  • Phytoplankton grow because of light and nutrients
  • Plankton are small organisms that drift with ocean currents
  • Phytoplankton: small cells that contain chlorophyll and drift with ocean currents
  • Photosynthesis: Chemical reaction that uses H2O and CO2 and energy from sunlight to produce glucose and oxygen.
  • Net Primary production is the difference between the amount of CO2 consumed by photosynthesis and amount of CO2 produced by respiration
  • NPP is positive when photosynthesis is greater than respiration
  • NPP is negative when respiration is greater than photosynthesis
  • When CO2 is consumed by photosynthesis it creates organic phytoplankton cells
  • 1/3 of the CO2 produced in industrial age are consumed by the ocean (largely through carbon pump)
Major phytoplankton Groups
  • Diatomes are made up of silica which is heavy
  • Flagellates avoid sinking
  • Photosynthetic bacteria are the main photosynthesizers and are able to grow with low nutrients
Light dependency of Phytoplankton Growth
  • Compensation light level is the light intensity where NPP=0
  • Photosynthesis compensates for respiration loss
  • Light limited region has low photosynthesis
  • Light saturated regions has max photosynthesis
  • Protoinhibited is too light to photosynthesize
4 Phyotoplankton nutrients
  • Nitrogen
  • Silica (for diatomes)
  • Phosphorous
  • Iron
Nutrient-Dependency Theory
  • Growth advantage is with small phytoplankton because it needs less nutrients
  • Deep ocean=light limited and Surface ocean=nutrients limited

As we warm the surface layer of the ocean and leave the deep layer cold, does that strengthen or weaken the thermocline? Answer: Strengthens because mixing decreases

Iron Limitation
  • Southern Ocean is iron limited
  • Iron is a micronutrient
  • The main source of Iron is dust
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