Phytoplankton

• bio-unlimited constituent


  the concentration of seawater co-varies with salinity and is essentially unaffected by biological or chemical activity
• bio-unlimited means that there is so much dissolved in the seawater that the organisms cannot ever use them up
• bio-intermediate concentration


  not at 0 but at a very low level
• bio-limiting concentration


  controlled by phytoplankton and bacterial processes and can reach a level of 0 concentration
• phytoplankton and <1% of worlds biomass but responsible for 50% of net photosynthesis
• phytoplankton can quickly fix carbon
• we can track the abundance of phytoplankton by tracking chlorophyll concentrations in the water
• photoyntheiss

  A) 6CO2

  B) 6H2O

  C) C6H12O6

  D) 6O2

  
• CO2 levels are lower at the surface due to phytoplankton photosynthesising
• bio-intermediate dissolved constituent


  constituent whose concentration in seawater is affected, but does not limit,biological activity (as its concentration does not go to zero in the surface sunlitwaters)
• nitrogen and phosphorus are key to many organisms
• bio-intermediate constituents are non-conservative so CO2 concentration varies from salinity
• photosynthesis but with nitrogen and phosphates

  A) 106

  B) CO2

  C) 16

  D) NO3-

  E) PO43-

  F) C106N16P

  G) 138

  H) O2

  
• higher concentration of nitrogen and phosphorus at depth due to dead and decaying organisms
• depth profile for phosphates

  
• carbonate system is important because it controls pH levels in oceans which affects marine life
• NO2- is nitrite
• NO2- has a similar profile to NO3-
• depth profile for NO3-

  
• depth profile for Si(OH)4

  
• Si(OH)4 is used by diatoms to create their glass-bodies
• Redfield ratio


  ratio of carbon, nitrogen, and phosphorus is in 116:16:1 throughout the worlds oceans
• some phytoplankton require Fe2+ and Zn2+
• Fe2+ and Zn2+ can limit growth of phytoplankton
• HNLC is high nutrient low chlorophyll regions
• HNLC are regions were the concentration of chlorophyll is low despite there being high nutrients
• areas with a low input of iron coincide with the HNLC regions
• iron can stimulate phytoplankton growth
• runoff from agricultural land can cause eutrophication in the seawater
• nitrogen is present in seawater as ammonium, nitrite, and nitrate