Unit 4: Aquaculture - Factors Affecting Marine Productivity

  • Created by: rosieevie
  • Created on: 22-05-15 14:25
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  • Factors Affecting Marine Productivity
    • Light - photosynthesi
      • Cannot penetrate deep water so seabed autotrophs only in shallow water
      • Deeper autotrophs are free-floating phytoplankton that move with currents
      • Storms disturb sediments - turbidity reduces depth which light can be absorbed
      • Titled axis causes polar regions to have sun never setting in the summer and never rising in the winter = seasonal variations in productivity
        • Summer algal blooms support rich food webs
    • Net Primary Productivity - energy captured by an autotroph during photosynthesis which has not been used in respiration
      • The sea has a low NNP
    • Nutrients
      • Autotrophs absorb nutrients directly from water - no soil
      • CO2 is abundant while NO3/PO4 is not
      • Organisms fall to seabed after dead = reducing nutrient availability and productivity
      • Continual supply of nutrients e.g. coast (rivers) = high productivity
      • Deep oceans = low productivity unless upwellings
      • Upwellings caused by surface winds or seabed topography changes
    • Ant/Arctic oceans - producers grow quickly with light, nutrients always available


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