Download Primary Production

11/17/2008
Primary Production
OCN201 Fall 2008
OCN201 Fall 2008
Zackary Johnson
Department of Oceanography
http://www.soest.hawaii.edu/oceanography/zij/education/ocn201 • Molecular evidence (i.e. DNA sequence) suggests that phylogenies are not
phylogenies are not always hierarchical
• There are mechanisms that account for this (sex, viruses, random uptake/incorporation p
/
p
of DNA)
• Complicated!
William 1999
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• Molecular evidence suggests genomes have fused and have resulted in different life stages
Williamson and Vickers
American Scientist Nov/Dec 2007
Major Concepts
9 Primary production is the first link in converting “environmental” energy to biological energy
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g
gy
9 Oceanic primary production is dominated by single celled “plants” called phytoplankton
9 Phytoplankton are exceptionally diverse
Primary production is typically limited by light or
9 Primary production is typically limited by light or nutrients
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What is primary production?
Primary = first, initial
P d i
Production = formation / creation of something
f
i /
i
f
hi
Primary production = the first conversion of energy from the environment into “biological” energy
What types of organisms are primary producers in the 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
chemical energy to create simple sugars
ex. H2S + 2O2 + CO2 Æ CH2O + SO4
ex. hydrothermal vent bacteria in worms
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Facts about marine primary production
What fraction of primary production is done by photosynthesizers?
(A)1%
(B)50%
(C)99%
Facts about marine primary production
9 Photosynthesizers contribute >99% of the total primary production in the ocean
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?
(A) 1%
(B) 50%
(C) 99%
Facts about marine primary production
9 Marine photosynthesis is about equal to terrestrial (land) photosynthesis (~50Gt/yr), even though the ocean is “blue”
9 Th
The ocean is much larger than land (70% vs 30%)
i
hl
th l d (70% 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.”
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Facts about marine primary production
What types of organisms are responsible for most marine primary production (photosynthesis)?
(A) Phytoplankton
(B) Seaweed
(C) Benthic (bottom attached) Algae
Facts about marine primary production
*Photosynthesizers in the ocean are dominated by single celled “plants” called phytoplankton
phyto = plant plankton = free floating
SSeaweed and benthic algae are
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regionally important (ex. coasts) but
contribute only a fraction of the total marine primary production
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Phytoplankton Diversity
Phytoplankton are exceptionally diverse
major groups of importance to marine ecosystems:
9
9
9
9
9
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9 Only one algal class, the Charophyceae, gave rise to land plants
land plants 9 include both prokaryotes and eukaryotes
9 many taxa have unique properties
9 this diversity has implications for the functioning of the ecosystem and biogeochemical cycles
diatoms
dinoflagellates
cyanobacteria
prymnesiophytes
prasinophytes
silicoflagellates
Blackenship, 2002
Phytoplankton Diversity
Diatoms
‐ Dominant primary producers in high latitude, coastal, and upwelling environments ‐ (high nutrient)
‐ siliceous oozes ‐ high latitude sediments
Centric – radial symmetry (pelagic, benthic)
Coscinodiscus
Thalassiosira
Corethron
Chaetoceros
Pennate – bilateral symmetry (pelagic, benthic)
Asterionella
Nitzschia
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Phytoplankton Diversity
Dinoflagellates
Important producers at high & low latitudes
Toxic blooms ‐ "red tides", paralytic shell‐fish poisoning
Zooxanthellae ‐ symbiotic in corals & some protozoans
Bioluminescence
Alexandrium
Gymnodinium
Ceratium
Phytoplankton Diversity
Cyanobacteria
Ubiquitous in temperate & warm‐water open ocean
particularly important in oligotrophic (nutrient poor) oceans
CHARACTERISTICS: Prokaryotic ‐ no organelles
S
Synechococcus ‐
h
small, coccoid
ll
id picoplankters
i l kt (~1 μm)
(~1
)
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% chlorophyll / primary production in the oligotrophic waters
Some use N2 (gas) as a source of nitrogen
Synechococcus
Trichodesmium
Prochlorococcus
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Phytoplankton Diversity
Prymnesiophytes
Carbonate rich blooms (high latitudes) – coccolithophorids
Antibacterial activity ‐ acrylic acid (Phaeocyctis)
Calcareous deposits in ocean sediments
Emiliania huxleyi
Phaeocystis (gel matrix)
Regulation of Primary Production
(Photosynthesis)
What is required for photosynthesis to occur?
Light (energy) + Nutrients (substrate)
What can limit primary production in the ocean?
Light or nutrients!
g
(phytoplankton get consumed too,
but we’ll get to that later…)
Phytoplankton in the Black Sea
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Types of Light Limitation Æ Light Decreases with Depth
0
0
light
1250
100
1000
2500
Aphotic
Zone
Depth (m)
Depth (m)
10
Euphotic
Zone
primary
production
d
3750
5000
10000
Light decreases exponentially with depth,
so most of ocean (at depth) is light‐limited
Types of Light Limitation Æ Mixing
Little Mixing
0
Depth (m)
50
Euphotic
Zone
Light OK
100
150
200
Lots of Mixing
Aphotic
Zone
Light Limited
If phytoplankton mix out of light layer (euphotic zone)
they become light limited
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Types of Light Limitation Æ Time (Daily / Seasonal), Latitude
Daily solar cycle (earth’s spinning) and seasonal cycle (earth’s D
il
l
l ( th’ i i ) d
l
l ( th’
rotation around sun / axis tilt) cause changes in light availability
ex. Half the year the North (and South Pole) receive no sun!
Types of Nutrient Limitation Æ Nutrients Increase at Depth
0
1o
Prod
Prod.
Euphotic
Zone
1250
100
1000
2500
“nutrients”
Aphotic
Zone
“nutrients”
Depth (m)
Depth (m)
10
0
3750
5000
10000
Nutrients (ex. PO4, NO3) accumulate at depth,
so most of ocean (at surface) is nutrient‐limited!
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Types of Nutrient Limitation Æ Spatial Patterns (ex. PO4)
Nutrients (ex. PO4, NO3) are abundant in certain regions (high latitudes, equator, coastal areas) because of physical forces (upwelling, mixing)
Pulse of a Planet
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Major Concepts redux
9 Primary production is the first link in converting “environmental” energy to biological energy
gy
g
gy
9 Oceanic primary production is dominated by single celled “plants” called phytoplankton
9 Phytoplankton are exceptionally diverse
Primary production is typically limited by light or
9 Primary production is typically limited by light or nutrients
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