Global Biogeochemical Cycles
Supporting Information for
Sources of new nitrogen in the Indian Ocean
Eric J. Raes1*, Peter A. Thompson2, Allison S. McInnes3, Hoang Minh Nguyen1, Nick
Hardman-Mountford1, 4 and Anya M. Waite5
1. The Oceans Institute, University of Western Australia, M047 35 Stirling Hwy Crawley, 6009 WA, Australia
*eric.raes@research.uwa.edu.au +61 (0)8 6488 1690
2. CSIRO Oceans and Atmosphere Flagship, GPO Box 1538, Hobart, 7001 TAS, 7001, Australia
3. University of Technology, Sydney, Plant Functional Biology & Climate Change. City campus 15 Broadway
Ultimo NSW 2007
4. CSIRO Oceans and Atmosphere Flagship, Private Bag 5, Wembley, 6913 WA , Australia
5. Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven and
Universität Bremen, D-28334 Bremen, Germany
Contents of this file
Text S1 to S6 and text to Table S1
Figures S1 to S6
Tables S1
Introduction
This supplementary material includes:

A description how the processed HPLC data were analysed using the diagnostic
pigments of the dominant phytoplankton taxonomic.

Information, as requested by the reviewer, where stable isotopes were
purchased from.

Additional information to show that enhanced spike concentrations did not
enhance our uptake rates.

Scatter plots, based on the principal coordinate (PC) loadings, visualised the
clustering of the different stations into Subtropical Water (STW n=79 CTD
stations) and Leeuwin Current water (LC n=98 CTD stations) for all voyages.
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
Additional information on the regional oxygen profile of the eastern Indian
Ocean.

Oxygen profiles with local depletion around 100-250m (lower oxygenated waters)
in three warm core eddies

Additional information on the vertical profile of the nutrient tracers within the
mixed layer in the Leeuwin Current waters and within Subtropical waters.
Table S1.
Pigment analysis:
Processed HPLC data were analysed using the diagnostic pigments of the dominant
phytoplankton taxonomic (Vidussi et al., 2001, Hirata et al., 2008, Aiken et al., 2009). It
is to be noted that diagnostic pigment analysis has its ambiguities (e.g. fucoxanthin is a
precursor for 19’-butanoyl oxyfucoxanthin and 19’-hexanoyloxyfucoxanthin); for more
detail see Aiken et al. (2009) and Uitz et al. (2006). This had only minor implications for
our data, as the microplankton represented a small fraction of the total phytoplankton
functional types (fraction range: <0.03).
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SYMBOL
DESCRIPTION
Allo
Alloxanthin
But
19’-Butanoyloxyfucoxanthin
Chlb
Chlorophyll β
Caro
Carotenes,ββ carotene+βε carotene
Diad
Diadinoxanthin
Diato
Diatoxanthin
Fuc
Fucoxanthin
Hex
19’-Hexanoyloxyfucoxanthin
Per
Peridinin
Viol
Violaxanthin
Zea
Zeaxanthin
DVChl
Divinyl chlorophyll α
Chlidea
Chlorophyllide a
TChl a
Total chlorophyll α = sum of Chl α+DVChl+Chlidea,
TC
Total carotenoids =
Allo+But+Caro+Diato+Fuc+Hex+Per+Viol+Zea
AP = accessory pigments
Sum of TC+Chlb+Chlc1+Chlc2+Chlc3
DP = diagnostic pigments
Sum of Allo+But+Chlb+Fuc+Hex+Per+Zea
Diatom proportion
Fuc/DP
Dinoflagellate
Per/DP
proportion
Microplankton
Diatom + Dinoflagellate proportion
Nano-flagellate
Allo+But+Chlb+Hex)/DP
picoplankton
Zea/DP
Table S1: Abbreviations for phytoplankton pigments and phytoplankton taxa
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Stable isotopes:
Ammonium Chloride N15
http://www.sigmaaldrich.com/catalog/product/aldrich/299251?lang=en&region=AU
Potassium Nitrate N15
http://www.sigmaaldrich.com/catalog/product/aldrich/335134?lang=en&region=AU
Sodium bicarbonate
http://www.sigmaaldrich.com/catalog/product/aldrich/372382?lang=en&region=AU
15
N2
http://www.sigmaaldrich.com/catalog/product/aldrich/364584?lang=en&region=AU
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Figure S1. Fig S1a and b present the spike concentrations (%) for a) NO3- assimilation
rates (nmol.L-1.h-1) and b) NH4+ assimilation rates (nmol.L-1.h-1).The trace additions (50
nmol.L-1) were based on Waite et al (2007a), Twomey et al (2007) and Hanson et al.
(2007). Enhanced trace additions (> 10%) did not increase assimilation rates in our study
area (Red lines: denote linear regressions r2= 0.003, slope= -0.0018, p= 0.57, n=120 for
NO3- assimilation rates and r2= 0.073, slope= -0.0106, p= 0.0019, n=129 for NH4+
assimilation rates respectively.
Figure S1: Spike concentrations did not enhance uptake rates
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Figure S2: Figure A2: Scatter plots, based on the principal coordinate (PC) loadings,
visualised the clustering of the different stations into Subtropical Water (STW n=79 CTD
stations) and Leeuwin Current water (LC n=98 CTD stations) for all voyages.
Temperature, salinity and dissolved O2concentrations explained more than 50% of the
variance (first PC) and defined the clustering of stations into STW and LC waters (see
Table 1).
Figure S2: PCA scatterplots for LC and STW waters.
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Figure S3:
(A) Area map with voyage tracks and CTD stations ±) in detail (B). Red circles for the
SS2010v05 CTD stations; black triangles for SS2011v04 CTD stations; blue squares the
CTD stations and brown circles for the flow through stations for the SS2012v04 and
green crosses for SS2013v04 voyage CTD stations. Arrows indicating poleward flowing
Leeuwin Current (LC) and Sub Tropical Water (STW). (C) Oxygen profile of the eastern
Indian Ocean. Regional depth vs temperature profile with dissolved oxygen
concentrations in colour. Data sourced from all available Argo floats and cruise voyages
conducted on the Southern Surveyor in 2010, 2011, 2012 and 2013. Regional water
masses, cold Subtropical waters and warm Leeuwin Current waters are highlighted by
STW and LC respectively. Shallow (100-200m) relatively lower dissolved oxygen layers
(DO) are highlighted by the black circle.
Figure S3: Oxygen profile in the eastern Indian Ocean.
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Figure S4: Shows three warm core eddies (WC1-2-3). Top panels denote depth (m)
profiles with temperature (˚C) as a colour overlay. Bottom panels depth (m) profile with
oxygen (μmol.kg-1) as a colour overlay. Relatively lower dissolved oxygen layers are
highlighted by a black circle
Figure S4: Oxygen profiles in three warm core eddies.
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Figure S5: present the shape of the vertical profile of the nutrient tracers within the
mixed layer in the Leeuwin Current waters. All the available in situ nutrient data
(μmol.L-1.h-1) within the MLD for a) NO3- Red lines: denote linear regressions r2=0.11,
p<0.0001, slope=0.0016; b) NH4+ r2=0.008, slope=-0.0001, p=0.12; c) PO4-3 r2=0.126,
slope=0.002, p<0.0001; and d) Si r2=0.084, slope=0.0014, p<0.0001 are plotted with
their corresponing MLD (m).
Figure S5: Vertical profile of the nutrient tracers in the Leeuwin Current.
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Figure S6: present the shape of the vertical profile of the nutrient tracers within the
mixed layer in the Subtropical waters. All the available in situ nutrient data (μmol.L-1.h-1)
within the MLD for a) NO3- Red lines: denote linear regressions r2=0.008, p= 0.119,
slope= 0.0006; b) NH4+ r2=0.0109, slope=0.0001, p=0.08; c) PO4-3 r2=0.007, slope=8x105
, p=0.155; and d) Si r2=0.013, slope=0.0011, p<0.0001 are plotted with their
corresponing MLD (m).
Figure S6: Vertical profile of the nutrient tracers within the mixed layer in the
Subtropical waters.
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References:
AIKEN, J., PRADHAN, Y., BARLOW, R., LAVENDER, S., POULTON, A.,
HOLLIGAN, P. & HARDMAN-MOUNTFORD, N. 2009. Phytoplankton
pigments and functional types in the Atlantic Ocean: a decadal assessment, 1995–
2005. Deep Sea Research Part II: Topical Studies in Oceanography, 56, 899-917.
HIRATA, T., AIKEN, J., HARDMAN-MOUNTFORD, N., SMYTH, T. & BARLOW,
R. 2008. An absorption model to determine phytoplankton size classes from
satellite ocean colour. Remote Sensing of Environment, 112, 3153-3159.
UITZ, J., CLAUSTRE, H., MOREL, A. & HOOKER, S. B. 2006. Vertical distribution of
phytoplankton communities in open ocean: An assessment based on surface
chlorophyll. Journal of Geophysical Research: Oceans (1978–2012), 111.
VIDUSSI, F., CLAUSTRE, H., MANCA, B. B., LUCHETTA, A. & MARTY, J. C.
2001. Phytoplankton pigment distribution in relation to upper thermocline
circulation in the eastern Mediterranean Sea during winter. Journal of
Geophysical Research: Oceans (1978–2012), 106, 19939-19956.
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