Primary production (14C) and phosphate availability in the south Pacific ocean

T. MOUTIN, P. RIMMELINLaboratoire d ’Océanographie et de Biogéochimie

Centre d ’Océanologie de Marseille

Surface

Ocean

CO2

CO2

CO2

DOC

Export production

Nutrients(N, P, Si, Fe)

POC

h

Moutin, 2000 (Océanis)

Biological pump : carbon transfert to the ocean interior by biological processCO2 : mineral carbon including carbonatesPOC : Particulate Organic CarbonDOC : Dissolved Organic Carbon

Scientific objectives :

To obtain reference measurements of primary production. To study phosphate availabilty, and its influence on planktonic community structure and on associated carbon fluxes.

CO2

P

h

POC

Primary production (JGOFS 14C method, 24-h of incubation duration)

Primary production

De

pth

(m)

0 2 4 6 80

25

50

75

100

125

150

0 2 4 6 80

25

50

75

100

125

150

East Mediterranean Sea(30°0E 34°0N)

PP = 183 mgC m-2 day-1

West Mediterranean Sea(6°1E 39°1N)

PP = 415 mgC m-2 day-1

Net absorption (mgC m-3)

LightDark

MINOS 96

PROSOPE 99

OLIPAC 94

POMME 01

Données SeaWIFS

« Against » biological diversity, a « simple » method to compare phytoplankton productivity in the ocean

Phytoplankton Productivity : Bangor, March 18th-22nd 2002

Net carbon absorption as a function of the incubation time (ti) beginning from sunrise

March 17, 2001

AN(ti) (mgC m-3) versus ti

0

10

20

30

40

0 6 12 18 24

5 m (50%)

mars-97

0

10

20

30

40

0 6 12 18 24

5 m (50%)

mars-97

AN(ti)/AN(24*) versus ti

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 6 12 18 24

apr-01

D=115

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 6 12 18 24

D=275

oct-01

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 6 12 18 24

D=72

march 01

AN(ti)/AN(24*) versus ti

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 6 12 18 24

apr-01

D=115

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 6 12 18 24

D=275

oct-01

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 6 12 18 24

D=72

march 01

Eastern North Atlantic

0

10

20

30

40

0 6 12 18 24

5 m (50 %)

April 25, 2001

0

10

20

30

40

0 6 12 18 24

5 m (50 %)

April 25, 2001

0

10

20

30

40

0 6 12 18 24

D=275

5 m (50 %)

October 2, 2001

0

10

20

30

40

0 6 12 18 24

D=275

5 m (50 %)

0

10

20

30

40

0 6 12 18 24

D=275

5 m (50 %)

0

10

20

30

40

0 6 12 18 24

D=275

5 m (50 %)

October 2, 2001

Secondary objective concerning primary production : to validate the model established in the Mediterranean Sea for daily primary production rates (dawn-to-dawn) calculation.

Phytoplankton Productivity : Bangor, March 18th-22nd 2002

POMME cruises in the Eastern North Atlantic Ocean

PO4

Conceptual scheme showing competitive absorbtion of phosphate by bacteria and phytoplankton and possible implications on the carbon cycle in a simple trophic chain model

(Moutin 2000 from Thingstad et al., 1997 and Thingstad 1998).

Heterotrophicflagellates

surface

ocean

Micro-zooplankton

Heterotrophicbacteria

Pico-phytoplankton

New Production

Regenerate production

Phosphate flux

DOC export POC export

DOC

Carbon flux

Nano-microphytoplankton

Meso-zooplankton

Si

------ +++++

PO4

HeterotrophicBacteria

Pico-phytoplankton

Nano-microphytoplankton

Carbon and phosphate uptakes 33P and 14C methods (Incubation duration << 24 h)

Biomass (Particulate Phosphate, Chlorophylle a (who?), Bacterial Biomass ?)

Phosphate availabilty -Characteritics of the phosphacline (Concentration vs depth measurements by the classic and/or the MAGIC method (if PO4<100 nM))-Turnover times measurements (=>Indirectly estimated orthophosphate concentration)-Dissolved Organic Phosphate concentration (labile DOP at surface only)

Size fractionation (0.2, 0.6, 2 µm)

Planktonic production (C & P)To study phosphate availabilty, and its influence on planktonic community structure.

One profile each day number 2 for « three days » stationsNeeds :

Radio-isotopes container CTD one hour before dawn2.5 liters per depth (max 12 depth)in situ

Primary production (JGOFS 14C method 24-h)

Planktonik production (C & P)

One profile each « one day » stationNeeds :

3 meters of working lab outside of the RA containerCTD two hours before solar noon4.5 liters per depth (max 9 depths)Deck incubators

ALOHA

SRP

N-limitationAbsence de

TrichodesmiumPrésence de

Trichodesmium

D. KarlJGOFS Conference ”Ocean Biogeochemistry: A New Paradigm”.13-17 April 2000. Bergen

D. Karl et al., Nature 1997.

Time

P-limitation

?

BIOSOPE

Image composite Seawifs

0

5

10

15

20

25

Printemps Ete Automne Hiver

PP

(n

M)

ALOHA

CHENAL

0

5

10

15

20

25

30

35

Printemps Ete Automne Hiver

SN

P (

mm

ol

m-2

)

ALOHA

CHENAL

Comparison between ALOHA and Chenal des Loyauté Station (DIAPALIS Cruises)Van Den Broeck et al., MEPS, in press.

Lowest orthohosphate turnover time measured

CHENAL

ALOHA : 2 d CHENAL : 4 h

0

2

4

6

8

10

12

14

16

Printemps Ete Automne Hiver

SR

P (

mm

ol m

-2) ALOHA

CHENAL

Collaborations :

-Frede Thingstad :-to study the phosphate cycle in the upper photic zone of oligotrophic ocean.

-France Van Wambeke : -to study bacterial production vs primary production and the role of heterotrophic bacteria in the DOP pool utilization.

-Dave Karl : (in discussion)-to compare phosphate availabilities in the South and the North Pacific gyres (ALOHA station).

0.2-0.6µm0.6-2µm>2µm

Stations

Particulate phosphate (nM)

0

4

8

12

16

20

24B

Chl a (µg l-1)

0.0

0.1

0.2

0.2-0.6µm

0.6-2µm

>2µm

A

Vmax/Ks (l nmol-1 h-1)

0.0

0.1

0.2

0.3

0.4

0.5

1 2 3 4 5 6 7

affinity (l nmol-1 h-1)

0.0

0.1

0.2

0.3

0.4

0.5D

Vmax (h-1)

0.0

0.5

1.0

1.5

2.0

2.5C

E

Figure 2 Size fractionation of biomass and studies of kinetics parameters for P-uptake along a west-east transect in the Mediterranean Sea (5°W-22°E). A: chlorophyll a, B: particulate phosphate; C: maximum uptake rate of phosphate; D: phosphate affinity and E: Michaelis-Menten parameters, Vmax divided by Ks. Each parameter is shown by size fractions (between 0.2 and 0.6 µm; between 0.6 and 2µm, and above 2 µm).

Gibraltar Ionnian Sea

Moutin, Thingstad, Van Wambeke, Marie, Slawyk, Raimbault & Claustre, 2002 (Limnol. Oceanogr.)

« Expected » results !PROSOPE Cruise

HIVER PRINTEMPS ETE AUTOMNE396 3,9 1,6 Mer Méditerranée370 2,4 0,9 Golfe du LionD1S9 D1S17 D1S20

9,02,1 Alboran

D1S2

1,71,5 OccidentaleD1S5

1,20,5 Orientale

D1S4

230 1,3 217 Océan Atlantique38 0,4 Golfe de Gascogne*

D1S3 D1S4 D1S1 Panache de la Gironde

8225 Upwelling au large du Maroc

D3S1

1182 152 168382 55 110 Nord Est (POMME)D2S3 D2S4 D2S4

504 107 10,8 4,0 68 Océan Pacifique175 37 2,4 0,3 2 Tropical Sud OuestD5S1 D5S1 D3S2 D5S1 D5S1 Chenal des loyauté

Temps de recyclage du phosphate (moyenne et écart-type en heure) dansles eaux de surface des océans (0-20 m), D5S1 signifie 5 profondeurs (D)et 1 station (S) échantillonnées (Sont inclues les valeurs obtenues par C.Labry* et N. Van de Broeck).

2.5 h

1 day

Turnover times

1 week

1 month

-12 5

-10 5

-8 5

-6 5

-4 5

-2 5

-5D

epth

(m

)

O ct-0 1 D ec -0 1 Jan -0 2 A p r-0 2 M ay -0 2 A ug -0 2

Sp r in g S u m m e r F a ll W in te r

0 .4

0 .8

1 .2

1 .6

2 .0

2 .4

2 .8

3 .2

3 .6

0

1

2

3

4

1 2 3 4 5 6 M IO

Stations

Pi (

nM

) d

édu

ites

de

T

Proposition d ’une méthode indirecte simple (Radio isotopique 33P) pour évaluer indirectement la concentration en orthophosphate (L.D. < 0.02 nM).

0.1

1.0

10.0

100.0

1000.0

0.1 1.0 10.0 100.0 1000.0

SRP (nM)

[PO

4]

( nM

)

ENAO Apr 2001

ENAO Sep 2001

1:1

Pi (

nM

) d

édu

ites

de

T

SRP (nM)

Mer Méditerranée

{Océan Atllantique Nord Est

Moutin, Thingstad, Van Wambeke, Marie, Slawyk, Raimbault & Claustre, 2002 (Limnol. Oceanogr.)

y = 0,005xMAGIC *25

y = 0,002xMAGIC *10

y = 0,0002xClassique

0

0,05

0,1

0,15

0,2

0,25

0,3

0 10 20 30 40 50

Concentration PO4 (nM)

Abs

orba

nce

(cuv

e 10

cm

)Nécessite l ’achat d ’unecentrifugeuse grand volume

2 nM

0,8 nM

20 nM

Limite de détectionet sensibilité attendue

Container Radio-isotopes IFREMER

0

5

0.2-0.6 0.6-2 >2 µm

0.00

0.05

0.2-0.6 0.6-2 >2 µm

0

400

0.2-0.6 0.6-2 >2 µm

0

4

0.2-0.6 0.6-2 >2 µm

0.0

8.0

0.2-0.6 0.6-2 >2 µm

0.00

0.08

0.2-0.6 0.6-2 >2 µm

Chlorophylle a µg l-1

Absorption de phosphate nM h-1

Phosphate particulaire nM

Station "UPWELLING" au large du Maroc Station "M IO" en mer Ionienne

Mission PROSOPE