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Major Concepts
Primary Production
OCN201 Fall 2007
Zackary Johnson
Department of Oceanography
Department of Oceanography
http://www.soest.hawaii.edu/oceanography/zij/education.html
9 Primary production is the first link in converting “environmental” energy to biological energy
9 Oceanic primary production is dominated by single celled “plants” called phytoplankton
9 Phytoplankton are exceptionally diverse
9 Primary production is typically limited by light or nutrients
What is primary production?
Primary = first, initial
Production = formation / creation of something
Primary production = the first conversion of energy from the environment into “biological” energy
What types of organisms are primary producers in the ocean?
What is primary production?
Photosynthesizers (plants): use sunlight energy to convert carbon dioxide into simple sugars
H2O + CO2 Æ CH2O + O2
Chemosynthesis (some types of bacteria): use chemical energy to create simple sugars
ex. H2S + 2O2 + CO2 Æ CH2O + SO4
ex. hydrothermal vent bacteria in worms
Facts about marine primary production
What fraction of primary production is done by photosynthesizers?
Facts about marine primary production
9 Photosynthesizers contribute >99% of the total primary production in the ocean
(A)1%
(B)50%
(C)99%
Chemosynthesis is important in certain areas (especially in areas where there is not light – ex. deep sea, deep sea vents, etc.), but is a small fraction of total primary production of the ocean.
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Facts about marine primary production
About what fraction of the earth’s primary production occurs in the ocean?
Facts about marine primary production
9 Marine photosynthesis is about equal to terrestrial (land) photosynthesis (~50Gt/yr), even though the ocean is “blue”
(A) 1%
(B) 50%
(C) 99%
9 The ocean is much larger than land (70% vs 30%)
9 Marine plants double every 2‐3 days, terrestrial plants average years 9 Thus, even though there is less “plant” material in the ocean, as a whole the ocean is about as productive as land. Sometimes called the “invisible forest.”
Facts about marine primary production
What types of organisms are responsible for most marine primary production (photosynthesis)?
Facts about marine primary production
*Photosynthesizers in the ocean are dominated by single celled “plants” called phytoplankton
phyto = plant plankton = free floating
(A) Phytoplankton
(B) Seaweed
(C) Benthic (bottom attached) Algae
Seaweed and benthic algae are
regionally important (ex. coasts) but
contribute only a fraction of the total marine primary production
Phytoplankton Diversity
Phytoplankton Diversity
Diatoms
‐ Dominant primary producers in high latitude, coastal, and upwelling environments ‐ (high nutrient)
‐ siliceous oozes ‐ high latitude sediments
Phytoplankton are exceptionally diverse
major groups of importance to marine ecosystems:
9
9
9
9
9
9
diatoms
dinoflagellates
cyanobacteria
prymnesiophytes
prasinophytes
silicoflagellates
9 Only one algal class, the Charophyceae, gave rise to land plants 9 include both prokaryotes and eukaryotes
9 many taxa have unique properties
9 this diversity has implications for the functioning of y
g
y
the ecosystem and biogeochemical cycles
Centric – radial symmetry (pelagic, benthic)
Coscinodiscus
Thalassiosira
Corethron
Chaetoceros
Pennate – bilateral symmetry (pelagic, benthic)
Blackenship, 2002
Asterionella
Nitzschia
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Phytoplankton Diversity
Phytoplankton Diversity
Cyanobacteria
Ubiquitous in temperate & warm‐water open ocean
particularly important in oligotrophic (nutrient poor) oceans
Dinoflagellates
Important producers at high & low latitudes
Toxic blooms ‐ "red tides", paralytic shell‐fish poisoning
Zooxanthellae ‐ symbiotic in corals & some protozoans
Bioluminescence
Alexandrium
CHARACTERISTICS: Prokaryotic ‐ no organelles
Synechococcus ‐ small, coccoid picoplankters (~1 μm)
Prochlorococcus – recently discovered, most abundant throughout the water column (107‐108 cells/liter)
Very small (0.6‐1.0 μm in diameter)
Responsible for ~50%
Responsible for 50% chlorophyll / primary production in the oligotrophic
chlorophyll / primary production in the oligotrophic waters
Some use N2 (gas) as a source of nitrogen
Ceratium
Gymnodinium
Synechococcus
Phytoplankton Diversity
Prochlorococcus
Trichodesmium
Regulation of Primary Production
(Photosynthesis)
Prymnesiophytes
Carbonate rich blooms (high latitudes) – coccolithophorids
Antibacterial activity ‐ acrylic acid (Phaeocyctis)
Calcareous deposits in ocean sediments
What is required for photosynthesis to occur?
Light (energy) + Nutrients (substrate)
Wh
What can limit primary production in the ocean?
li i i
d i i h
?
Light or nutrients!
Phaeocystis (gel matrix)
Emiliania huxleyi
(phytoplankton get consumed too,
but we’ll get to that later…)
Phytoplankton in the Black Sea
Types of Light Limitation Æ Light Decreases with Depth
0
Euphotic
Zone
100
1000
10000
0
1250
50
2500
Aphotic
Zone
Deptth (m)
Deptth (m)
10
0
primary
production
Depth (m)
light
Types of Light Limitation Æ Mixing
150
5000
200
Lots of Mixing
Euphotic
Zone
Light OK
100
3750
Light decreases exponentially with depth,
so most of ocean (at depth) is light‐limited
Little Mixing
Aphotic
Zone
Light Limited
If phytoplankton mix out of light layer (euphotic zone)
they become light limited
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Types of Nutrient Limitation Æ Nutrients Increase at Depth
0
1o
Prod.
Euphotic
Zone
Deptth (m)
10
ex. Half the year the North (and South Pole) receive no sun!
Types of Nutrient Limitation Æ Spatial Patterns (ex. PO4)
1250
100
1000
Daily solar cycle (earth’s spinning) and seasonal cycle (earth’s rotation around sun / axis tilt) cause changes in light availability
0
2500
“nutrients”
Aphotic
Zone
“nutrients”
Depth (m)
Types of Light Limitation Æ Time (Daily / Seasonal), Latitude
3750
5000
10000
Nutrients (ex. PO4, NO3) accumulate at depth,
so most of ocean (at surface) is nutrient‐limited!
Pulse of a Planet
Nutrients (ex. PO4, NO3) are abundant in certain regions (high latitudes, equator, coastal areas) because of physical forces (upwelling, mixing)
Major Concepts redux
9 Primary production is the first link in converting “environmental” energy to biological energy
9 Oceanic primary production is dominated by single celled “plants” called phytoplankton
9 Phytoplankton are exceptionally diverse
9 Primary production is typically limited by light or nutrients
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