7.1-7.2 Primary Production

7.1 Primary Production

  • the creation of new organic matter from inorganic substrates— base of food web for marine life

  • usually refers to photosynthesis by algae and phytoplankton and also chemosynthesis by bacteria without light

  • 6CO2 + 6H2O → C6H12O6 (glucose) + 6O2

Chemosynthesis

  • energy from oxidation of inorganic materials (hydrogen sulfide)

  • gross primary productivity— the amount of organic material made by producers

  • marine productivity is more efficient than terrestrial

7.2 The Producers

  • 95% of marine primary produce from phytoplankton

3 types of phytoplankton

  1. Diatoms- single celled algae, very high photosynthetic efficiency

  2. Dinoflagellates

  3. Coccolithophores— abundant in warm, open oceans

7.3 Factors Influencing Production

Factors: light and nutrients

Light: 

  • needed for photosynthesis and only possible in the upper layers of the ocean

Nutrients:

  • needed by all marine primary consumers

  • major ones for phytoplankton are nitrogen and phosphorus

  • nutrients are not evenly distributed throughout the water column

  • surface waters are nutrient poor because its quickly eaten up by phytoplankton and more abundant in deeper water and usually stay there unless there is upwelling

Patterns of Primary Production

  • phytoplankton increases near coastal areas because they are located closer to nutrient runoff from land and because shallow waters prevent nutrients from sinker into unreachable waters

  • primary production is limited in coastal areas because of the significant thermocline that prevents nutrients from rising to the surface

  • at the poles, theres less thermocline so they receive more nutrients but also get less sunlight (only in spring and summer will productivity spike)