The Marine Food Webs The Marine Food Webs 1) What regulates a planktonic food web? I) Light II) Nutrients III)Importance of the Type of Nutrient IV) Size and Export V) Food Web Structure 2) Examples of what controls a food web I) El Nino II) Iron Ex r Schofield ([email protected])
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The Marine Food WebsThe Marine Food Webs1) What regulates a planktonic food web?
I) LightII) NutrientsIII) Importance of the Type of NutrientIV) Size and ExportV) Food Web Structure
2) Examples of what controls a food webI) El NinoII) Iron Ex
3) The 1% light levelfor the majority of the is 100 m or less?
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1012
Julian Day
Dep
th (m
)
0 633 1267 1900
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1012
Julian Day
Dep
th (m
)
0 633 1267 1900
μmol
pho
tons
(m-2 s
-1)
Dep
th (m
)
Calendar Day
μmol photons m-2 s-1
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1012
Julian Day
Dep
th (m
)
0 500 1000 1500
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1000
1500
2000
0
Calendar Day
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1012
Julian Day
Dep
th (m
)
0 633 1267 1900 Oliver et al.JGR 2004
0
2
4
6
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10
0.1 1 10 100 1000
Irradiance (mol photons m-2 s-1)
Prod
uctiv
ity (m
g C
mg
Chl
a-2 h
-1)
Pmax
Ik = Pmax/Respiration
Irradiance IntensityTemperature
time
PP Ed
Irradiance IntensityTemperature
Z (meters)
Z(meters)
net primaryproduction
net photosynthesis
phytoplanktonrespiration
communityrespiration
euphotic zone
Critical depth NPP = Rc
Note these are integratedover the water column.
CHL a
>3
0
mg m-3
UML
Low wind High wind
IrradianceIrradiance
PhytoplanktonPhytoplankton
Physical mixing processes
Nutrients
1993 1994Dec JanSept Oct Nov
0
50
100
Dep
th (m
)
0
50
100
Dep
th (m
)
0
50
100
Dep
th (m
)
0
50
100D
epth
(m)
NO3- (
M)
Chl a
(mg
m-2)
PO43-
(M
) Si
(OH)
4 (M
)
0
3
10
45
0.8
2.5
15
80
Biomass and NutrientsSta E (1993-1994)
Nutrient concentration (can be nitrogen, phosphorus)
Nut
rient
Upt
ake Vmax
Ks
NO3 NO3
NO3
NO3
NO3
NO3
Austin Powers Fat Bastard Model System, eats fast when a lot available, but sloppy & alot ends on his shirt not in his belly
Miss Manner Model System, eats slow and efficiently, everything ends up in her belly
0
2
4
6
8
10
12
diatoms coccos dinos greens
KsNO3-
KsN
O3-
(uM
)
0
0.2
0.4
0.6
0.8
1
diatoms coccos dinos greens
Vmax NO3/C
m
ol N
/m
olC
/day
Nutrient Uptake Varies with Phytoplankton SpeciesNutrient Uptake Varies with Phytoplankton Species
Different Strategies of Nutrient UtilizationDifferent Strategies of Nutrient Utilization
Diatoms
•High Vm •High Ks
Coccolithophores
•Low Vm •Low Ks
High or fluctuating nutrientsHigh mixing, upwellingLow average irradiance, light fluctuationsHigh turbulence
Chronically oligotrophicStratified conditionsHigh average irradiance Low turbulence
Cullen et al. 2003Cullen et al. 2003
2.5
3
3.5
4
4.5
5
0 0.5 1 1.5 2 2.5 3 3.5
Total Chlorophyll (ug/L)
Size
Nutrients are low Nutrients are high
n = 6695
Remember small cells, higher surface to volume ratioRemember small cells, higher surface to volume ratio
Various phytoplankton concentrations of earth's oceans.Various phytoplankton concentrations of earth's oceans.
• Purple and blue areas - unproductive regions (open ocean areas)
• Red and orange areas - productive regions (coastal areas, small basin)
180oW 135oW 90oW 45oW 0 45oE 90oE 135oE 180oE90oN
60oN
30oN
0o
30oS
60oS
90oS
More recently satellite algorithms have been developed More recently satellite algorithms have been developed for some phytoplankton taxa detectionfor some phytoplankton taxa detection
Sequestration of Atmospheric CarbonSequestration of Atmospheric Carbon
Chisholm, 2000
MARINE SNOW
What is it?What is it?
How is formed? (particle-particle, sticky, virus)How is formed? (particle-particle, sticky, virus)
Why is it important?Why is it important?
What is Marine Snow?
Hey look!Here comes a
Diatom!Diatom
Snow FormationWhile photosynthesizing DOM is exuded These molecules encounter one
another in the aqueous environment
Through cation binding the molecules come together forming larger particles
The particles are extremely “sticky” and easily adhere to each other as well as other particles in the water
Marine snow particles fromMarine snow particles fromoff New Jerseyoff New Jersey
Irradiance
Elemental Flux
CO2N2
Fe
CarbonN2Fe
rivers
Wind
Continental shelf
Cont
inen
tal s
lope
S
Mixing processes
New Nutrients
Phytoplankton
Sinkage & Senescence
Particle Dynamics
Zooplankton
Higher Trophic LevelsM
ixed
Lay
er D
epth Regenerated
Nutrients
Water column depthM
ixed
Lay
er
Dep
th
A Natural Experiment: Are nutrients from the deepocean driving the primary productivity?
El Nino
Top: “normal” forcing condition
Bottom: El Niño forcing condition
Open University, 1998
Normal
El Nino
Top: normal Bottom: El Niño condition
Open University, 1998
Normal
El Nino
JPL
El Nino
La Nina
Notecoastal effect
HNLC
So lets do an experiment: What limits productivity in a high So lets do an experiment: What limits productivity in a high nitrogen/phosphorus ocean? Is it iron limited?nitrogen/phosphorus ocean? Is it iron limited?
Go to a HNLC Ocean (Antarctic), going means sending a graduate Go to a HNLC Ocean (Antarctic), going means sending a graduate student, dump iron in the ocean and watch the phytoplankton respond.student, dump iron in the ocean and watch the phytoplankton respond.
Iron Patch Health
Red = HealthyRed = HealthyBlue = Not happyBlue = Not happy
GLOBALGLOBAL
Cell size effects the trophic transfer of matter Cell size effects the trophic transfer of matter and energy in the food weband energy in the food web