tom browning & heather bouman (oxford) mark moore (nocs)
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JC068 Phytoplankton: Concentrations, Species, and Physiological Status UK-GEOTRACES: Ocean Micronutrient Cycles WP5: Biological responses and cycling of micronutrients. Tom Browning & Heather Bouman (Oxford) Mark Moore (NOCS). - PowerPoint PPT PresentationTRANSCRIPT
JC068 Phytoplankton:Concentrations, Species, and Physiological Status
UK-GEOTRACES: Ocean Micronutrient Cycles WP5: Biological responses and cycling of micronutrients
Tom Browning & Heather Bouman (Oxford)Mark Moore (NOCS)
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
NASA MODIS January 2012 SST
Tem
pera
ture
(°C)
Sea Surface Temperature
JC068 CTD Temperature
Dept
h (m
)
45
30
15
0
Tem
pera
ture
(°C)30°S
40 °S
50°S
50°W 30 °W 10°W 10°E
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
Macronutrients
Nitr
ate
(µM
)Ph
osph
ate
(µM
)
Dept
h (m
)De
pth
(m)
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
Chlo
roph
yll C
once
ntra
tion
(m
g/m
3 )
NASA MODIS January 2012 Chlorophyll
Phytoplankton Biomass
JC068 Bottle Data: Chlorophyll ConcentrationDe
pth
(m)
10
1
0.1
0 Chlo
roph
yll C
once
ntra
tion
(m
g/m
3 )
30°S
40 °S
50°S
50°W 30 °W 10°W 10°E
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
JC068
D357
Chlorophyll Concentration (mg/m3)
Phytoplankton Biomass - Climatology
NASA MODIS Chlorophyll, 9 km2 resolutionMonth averaged
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
a ph(4
40)*
(m2 m
g-1)
Chlorophyll a-specific absorption at 440 nm: indicator of phytoplankton size
Larger aph(440)* = smaller cells
Phytoplankton Absorption
Samples run by Christian Utschig
Dept
h (m
)
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
Nanophytoplankton (2-20 µm) Picophytoplankton (0.2-2 µm)
ProchlorococcusSynechococcus
Total Bacteria
Analytical Flow Cytometry
Cell counts (cells/µL)
Dept
h (m
)De
pth
(m)
Dept
h (m
)
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
Fv/Fm: Thought to be influenced by phytoplankton species, light climate, micronutrients and macronutrients.
Fv/Fm in JC068 transect, a signature of Fe limitation
Phytoplankton PhotophysiologyFv/Fm
Dept
h (m
)
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
I C Fe0.1
0.150.2
0.250.3
0.350.4
0.45
Fv/F
m
I C Fe0.2
0.220.240.260.28
0.30.320.340.36
Fv/F
m
I C Fe0.2
0.250.3
0.350.4
0.450.5
0.550.6
Fv/F
m
ΔFv/
F m
= F
v/F m
Fe
amen
ded
bottl
e –
F v/
F m C
ontr
ol b
ottle
Control Fe addition (2 nM)Initial
Immediate analysis 24 hour incubation 24 hour incubation
Fe incubation experiments
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
=
Gough Island
Two dominant regimes:
1) Subtropical Gyre type waters• Low macronutrients• Fe replete• High irradiance (near surface)
2) AAC source waters• High macronutrients• Fe limited• Possible light limitation
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary
Chlo
roph
yll
Conc
entr
ation
(m
g/m
3 )
Dept
h (m
)
A: Warmer, low macronutrients, stratified
B: Colder, high macronutrients, deeper mixed layer
Low surface chlorophyll Higher surface chlorophyll
Dominated by smaller cells Dominated by large cells
Fe replete Fe limited
A B A
Samples to be run: HPLC; microscopy; N-Fixers; DNA
Introduction Chlorophyll Cell Size Phytoplankton Types Fe Limitation Summary D357
Pre-bloom (leg 1) and bloom (leg 2) conditionsCause: shallowing of mixed layer = increased light
Depressed mixed layer Fv/Fm = Fe limitationOctober – January: shift from Fe limited to macronutrient limited environment as bloom consumes macronutrients.
1st LEG
2nd LEG