Environmental control on phytoplankton size- fractionated primary production in the tropical and subtropical Atlantic, Indian and Pacific oceans The 45 th International Liège Colloquium. Liège (Belgium), 13-17 May 2013 M. Huete-Ortega, P. Cerme ñ o , A. Fernández, B. Fernández-Castro, N. González, D. López- Sandoval, B. Mouriño-Carballido, C. Sobrino and E. Mara ñó n
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Environmental control on phytoplankton size-fractionated primary production in the tropical and subtropical Atlantic, Indian and Pacific oceans The 45.
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Environmental control on phytoplankton size-fractionated primary
production in the tropical and subtropical Atlantic, Indian and Pacific oceans
The 45th International Liège Colloquium. Liège (Belgium), 13-17 May 2013
M. Huete-Ortega, P. Cermeño , A. Fernández, B. Fernández-Castro, N. González, D. López-
Sandoval, B. Mouriño-Carballido, C. Sobrino and E. Marañón
Phytoplankton size structure…
Ecosystems dominated by small phytoplankton:
• Organic matter is recycled into the microbial loop
Ecosystems dominated by large phytoplantkon:
• Organic matter transferred towards higher trophic levels or to the deep ocean
Barber & Hiscock 2006 Global Biog. Cycles
…influences the organization of the pelagic trophic chain and plays an important role in the global carbon cycle
• Incubations on deck following the 14C method (3 clear, 1 dark bottles). Dawn-Sunset incubations.
• Size-fractionated primary production estimated at Surface, 20%PAR, 1%PAR: micro- (>20 µm ESD), nano- (20-2 µm ESD) and pico-phytoplankton (2-0.2 µm ESD)
• Total primary production estimated at 50%PAR and 7%PAR
Depth-integrated total primary production (mgC m-2 h-1)
Integrated total PP ranged 7-70 mgC m-2 h-
1 in the subtropical and tropical Atlantic, Indian and Pacific Oceans with higher values towards the coast and in the areas influenced by equatorial upwellings.
Microphytoplankton primary production (mgC m-3 h-1)
Atlantic Ocean
-20 -10 0 10 20-150
-100
-50
De
pth
(m
)
S N EW W EIndian Ocean
120 130 140-100
-50
Dep
th (
m)
30 40 50 60 70 80 90 100 110
-100
-50
Dep
th (
m)
W E EWPacific Ocean
-20 -10 0 10
-100
-50
Dep
th (
m)
-140 -130 -120 -110 -100 -90
-100
-50
Dep
th (
m)
S N W E
Nanophytoplankton primary production (mgC m-3 h-1)
Atlantic Ocean
-20 -10 0 10 20-150
-100
-50
De
pth
(m
)
0.01
0.03
0.05
0.07
0.09
0.11
0.13
0.15
0.17
0.19
0.21
0.23
0.02
0.04
0.06
0.08
0.1
0.12
0.14
S N EW W EIndian Ocean
30 40 50 60 70 80 90 100 110
-100
-50
Dep
th (
m)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
120 130 140-100
-50
Dep
th (
m)
W E EWPacific Ocean
-20 -10 0 10
-100
-50
Dep
th (
m)
-140 -130 -120 -110 -100 -90
-100
-50
Dep
th (
m)
0
0.2
0.4
0.6
0.9
1.2
1.6
S N W E
Picophytoplankton primary production (mgC m-3 h-1)
-20 -10 0 10
-100
-50
Dep
th (
m)
-140 -130 -120 -110 -100 -90
-100
-50
Dep
th (
m)
0
0.2
0.4
0.6
0.9
1.1
1.5
Pacific Ocean
Atlantic Ocean
-20 -10 0 10 20-150
-100
-50
De
pth
(m
)
0.02
0.05
0.08
0.11
0.14
0.17
0.2
0.23
0.26
0.29
0.32
0.35
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
S N EW W EIndian Ocean
30 40 50 60 70 80 90 100 110
-100
-50
Dep
th (
m)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.18
0.2
0.24
0.26
120 130 140-100
-50
Dep
th (
m)
0.02
0.06
0.1
0.14
0.18
0.22
0.26
0.3
0.34
0.38
0.42
0.46
W E EW
S N W E
% contribution of picophytoplankton PP to total
Indian Ocean
W E EW 120 130 140-100
-50
De
pth
(m)
30 40 50 60 70 80 90 100 110
-100
-50
Dep
th (
m)
Pacific Ocean
S N W E-20 -10 0 10
-100
-50
Dep
th (
m)
-140 -130 -120 -110 -100 -90
-100
-50
Dep
th (
m)
Atlantic Ocean
S N EW W E-20 -10 0 10 20-150
-100
-50
De
pth
(m
)
-70 -60 -50 -40 -30 -20
-150
-100
-50
Variability of N diffusive fluxes, stability and mld
Influence of physical variables on phytoplankton PP
N diffusive fluxes Brunt-Vaisala freq.
Mixed layer depth
Surface total PP -0.03(0.865) 0.36 (0.000) -0.38 (0.000)
20%PAR total PP 0.19 (0.199) 0.36 (0.000) -0.14 (0.120)
1%PAR total PP 0.23 (0.117) -0.14 (0.137) 0.10 (0.260)
• Similar patterns for size-fracionated PP were found in the subtropical and tropical oceans, being the picophytoplankton the size class with higher primary production rates. The contribution of microphytoplankton to total PP increased in the stations closer to the coast or under the influence of equatorial upwellings.
• Integrated total PP was in general around 10 mgC m-2 h-
1 in the subtropical and tropical oceans, except in those stations under the influence of equatorial upwellings or close to the coast.
• Water column stability, N diffusive fluxes and mixed layer depth showed a size-differential relationship with phytoplankton PP that also varied with the sampling depth.
Future work: 1) futher analysis about the influence (linear regression) of physical variables on the phytoplankton size-fractionated PP including their combined effect (multiple linear regression and rda analysis); and 2) to explore this relationship by biogeochemical provinces.
Acknowledgements
Thanks to all the people that contributed to the succesful development of the Malaspina 2010 Expedition, including the captain and crew of the RV Hespérides and the members of the UTM technical staff