Primary%20Production

1
Primary Production
Global chlorophyll concentrations for Oct. 2000
2
Feb 5, 1998 uniformly low pigment concentrations
during all seasons
3
Primary Productivity

• Photosynthesis
• Involves the use of light energy in the
  conversion of inorganic carbon into organic
  carbon.
• Photosynthetic organisms include terrestrial
  plants, seaweeds, phytoplankton, blue-green
  algae, and zooxanthellae.

4
Primary Productivity

• Chemosynthesis
• Involves the use of energy released by the
  catalysis of certain inorganic reaction to
  convert inorganic carbon into organic carbon.
• Chemosynthetic organisms include hydrothermal
  vent bacteria.

5
Table 1. Average net primary production and
biomass of aquatic habitats. Data from R.H.
Whittaker and G.E. Likens, Human Ecol. 1
357-369 (1973).
6
Primary Production Limitations

• light
• nutrients

Photic Zone
Photosynthesis
No Photosynthesis
Aphotic Zone
7
Primary Productivity

• Gross Primary Productivity (GP)
• The rate of production of organic matter from
  inorganic materials by autotrophic organisms
• Respiration (R)
• The rate of consumption of organic matter
  (conversion to inorganic matter) by organisms.
• Net Primary Productivity (NP)
• The net rate of organic matter produced as a
  consequence of both GP and R.

8
Primary Productivity

• NP GP R

Note that R is a negative value because it
results in the reduction of organic matter.
9
Phytoplankton
Zooplankton
10
RP
11
Plankton Sampling
12
(No Transcript)
13
Plankton Size
Picoplankton (.2-2 µm) Nanoplankton (2 - 20
µm) Microplankton (20-200 µm) Macroplankton
(200-2,000 µm) Megaplankton (gt 2,000 µm)
microplankton
picoplankton
nanplankton
14
Light Dark Experiments
Respiration C6H12O6 6O2
6CO2 6H2O
15
buoy
dark bottle
light bottle
respiration
photosynthesis respiration
weight
16

• LIGHT LEVELS have a major impact on productivity
• light intensity
• - with depth
• - penetration depends on water clarity
• light quality
• changes with depth
• longer (e.g., red) more quickly
• amount of light
• - to little or too much light inhibit
  photosynthesis
• primary production
• - different primary producers peak production at
  
• different light intensities
• (algae gtdiatomsgtdinoflagellates)
• compensation depth
• - depth at which rate of photosynthesis rate
  of
• respiration

17

• VERTICAL MIXING also influence productivity
• critical depth
• depth at which net photosynthesis per mixing
  cycle exceeds net respiration
• determined by the time spent at different depths
  due to vertical mixing

• Upwelling zones
• Thermocline layer
• Diurnal vertical migration
• Langmuir vortices

18

• NUTRIENTS often limit productivity
• inorganic nutrients
• - nitrogenous compounds (NO3, NO2, NH3)
• - phosphates (PO4)
• trace elements may also be important (e.g., Fe,
  
• Cu)
• nitrate concentrations in rich seawater 1/10,000
  
• of rich soil
• nutrients produced by
• - excretion
• - surface runoff
• - upwelling

19

• Productivity varies TEMPORALLY and SPATIALLY
• generally highest over continental shelves over
  the shelf itself it is highest just offshore
• seasonality more pronounced at high latitudes
• at mid latitudes, productivity peaks both spring
  and fall

20
Primary Production
biomass
zooplankton
phytoplankton
Winter Spring Summer Fall
North Atlantic- temperate climate
21
Arctic
zooplankton
phytoplankton
Winter Spring Summer Fall
22
Tropical
zooplankton
phytoplankton
Winter Spring Summer Fall
23
Environmental Factors Affecting Primary Production