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

Oscar Schofield (oscar@ahab.rutgers.edu)

autotrophsautotrophs

omnivores omnivores

carnivorescarnivores

Pyramimonas parkeae

Dunaliella tertiolecta

Gephyrocapsa oceanica

Ceratium sp.

Thoracosphaera heimii

Ditylum brightwellii Diatom sp.

I) Light

Z (meters)

Irradiance Intensity

Lambert Beers LawEd2 = Ed1e-z*Kd

Ed2

Ed1z1

z2

z

1) Because of Lambert Beers Lawthe ocean is dim

2) Plant life is dependent on light

3) The 1% light levelfor the majority of the is 100 m or less?

202 204 206 208 210 212 214

02468

1012

Julian Day

Dep

th (m

)

0 633 1267 1900

202 204 206 208 210 212 214

02468

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

202 204 206 208 210 212 214

02468

1012

Julian Day

Dep

th (m

)

0 500 1000 1500

500

1000

1500

2000

0

Calendar Day

202 204 206 208 210 212 214

02468

1012

Julian Day

Dep

th (m

)

0 633 1267 1900 Oliver et al.JGR 2004

0

2

4

6

8

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

Iglesias-Rodriguez et al. 2000

Surface chlorophyll from CZCS

Vertical distribution of Chl from 21,000 profiles

Mixed layer depth from NOAA-NODC archive

Surface nutrients

Brunt-Vaisala

57 provinces on the basis of:

Longhurst 1995

IrradianceIrradiance

ZooplanktonZooplankton

Higher Trophic LevelsHigher Trophic Levels

PhytoplanktonPhytoplankton

Physical mixing processes

Nutrients

GRAZERS in the plankton sea

soft-bodies, asexual, consumessoft-bodies, asexual, consumesall particle sizes, bloom & bust all particle sizes, bloom & bust

hard-bodies, sexual, consume hard-bodies, sexual, consume specific particle size ranges, specific particle size ranges, roving bandsroving bands

phytoplankton

zooplankton

fish

1000

100

10

0.1

0.1 This assumes atrophic transfer

efficiency of 10%

Upwelling zones (2 trophic levels)Phytoplankton Anchovies (20 % transfer efficiency)

Coastal Regions (4 trophic levels)Phytoplankton herbivorous zooplank.carnivorous zooplank.fish

(15% efficiency)

Open ocean (5 trophic levels)Phytoplanktonherb. Zooplank.carniv. Zooplank.carniv. Fishtuna(10% efficiency)

Area Plant prod. Efficiency Trophic levels Est. fish

Open 39*109 10% 5 4*106

Ocean

Coastal 8.6*109 15% 4 29*106

Ocean

upwelling 0.23*109 20% 2 46*106

(metric tonsper year)

(metric tonscarbon per year)

IrradianceIrradiance

SinkageSinkage & & SenescenceSenescence

Particle DynamicsParticle Dynamics

Particle Flux (Carbon flux)Particle Flux (Carbon flux)

ZooplanktonZooplankton

Higher Trophic LevelsHigher Trophic Levels

PhytoplanktonPhytoplankton

Physical mixing processes

Nutrients

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

• Cullen et al.

(Cullen et al., 2002)

(from N.Gruber)

(Takahashi et al 1995)

Net CO2 flux

Example: variability in carbon uptake

MARTIN GLACIAL & INTERGLACIAL