Marine phytoplankton and the changing ocean iron cycle

In the format provided by the authors and unedited. Marine phytoplankton and the changing ocean iron cycle D. A. Hutchins 1 * and P. W. Boyd 2 SUPPLEMENTARY INFORMATION DOI: 1.138/NCLIMATE3147 NATURE CLIMATE CHANGE www.nature.com/natureclimatechange 1 216 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

Marine phytoplankton and the changing ocean iron cycle Supplementary Information I. Supplementary Figures A) Global)Fe)cycle) B) Global)Ocean)Change)) Physiology) Reduced)Fe)uptake) Floris<cs) Altered)Fe)quotas) Fate)of)bio<c)Fe) Physiology) Luxury)Fe)uptake) "))Fe)demand))+) 4))CO 2) ))75) ) )))))))))Today)))Temp)))))+3C).2)).1)))))).1))).2)).3))).4)).5)) "))))Fe)supply)))))))+) "))Fe)demand))+) PAR))higher) )))))))))Today))))Temp))))+3C) S"Figure)1.)Sequence)of)changes)to)the)iron)uptake)of)resident)phytoplankton)in)a)future)ocean)in)response)to:)cumula<ve)effects)of))modifying)the)iron)cycle;)Feedbacks)to)iron)) supply)are)in)red.)b))upper)plot,)influence)of)warming)(black)symbols),)acidifica<on)(blue)symbols),)and)both)(red)symbol))on)colonial)n)fixers;)lower)plot)impact)of)warming)(black)) symbols),)shallower)mixed)layer)depth)(green)symbols),)and)both)(red)symbols))on)polar)diatoms.)panel)a)is)semi"quan<ta<ve)and)based)on)studies)from)(wells,)1999;)) Hutchins)et)al.,)22;)Boyd)et)al.)27;)Wilhelm)et)al.,)213),)whereas)B)is)largely)conceptual)and)based)on)preliminary)data)in)S"Table)1)and)S"Figure)2.)

Crocosphaera:+N A. N 2 fixation 2 +fixaon+rates+as+a+funcon+of+ B. Cellular Fe quota 5 pco 2+ and + Fe # N 2 fixation (nmol cell -1 hour -1 ) N 2 fixation (nmol cell -1 hour -1 ) 3e-8 2e-8 1e-8 3e-8 2e-8 1e-8 Fe-replete Fe-limited 19 38 75 pco2 (ppm) Fe:P ratio (mmol:mol) Fe:P ratio (mmol:mol) 4 3 2 1 5 4 3 2 1 Fe replete Fe limited 19 ppm 38 ppm 75 ppm pco2 S%Figure#2.#A)#N 2 &fixa)on&rates&and&b)&cellular&fe&quotas&(as&fe:p&ra)os,&mmol:mol)&as&a&func)on&of&growth&co 2 && concentra)ons&in&feareplete&(top&panels)&and&fealimited&(bodom&panels)&cultures&of&the&unicellular&n 2 &fixing&& cyanobacterium&crocosphaera.&n 2 &fixa)on&rates&and&fe&quotas&are&linearly&related&to&co 2 &levels&in&feareplete&cultures,&& but&both&rates&and&quotas&are&low&and&independent&of&co 2 &in&fealimited&cultures.&&values&are&means&and&error&bars& are&standard&devia)ons&of&triplicate&cultures&(from&fu&et&al.&28).& &

Fe:P ratio (mmol:mol) 18 16 14 12 1 8 6 4 2 37 ppm 75 ppm pco2 S"Figure)3.))Cellular'Fe'quotas'(as'Fe:P'raos,'mmol:mol)'increase'~4%'when'cultures'of'the'N 2 @fixing'cyanobacterium'' Trichodesmium'are'grown'using'trace'metal'clean'methodology'at'projected'year'21'CO 2 'levels'(75'ppm),'relave'to'' cells'grown'at'near@present'day'co 2 'concentraons'(37'ppm).''cellular'fe'and'p'was'measured'using'inducvely'coupled'' Plasma'Mass'Spectrometry'(ICP@MS),'as'described'in'Fu'et'al.'(28).'Values'are'means'and'error'bars'are'standard'deviaons'' of'triplicate'cultures'(hutchins'unpublished'data).'

II. Supplementary Table Study Organism Status Change Assumption IUE increase Sunda and Thalassiosira Fe- limited 1 o C 15.4 to 18.8 Huntsman pseudonana (85 PFD) warming 211 (22%) Clarke 1983, Southern Ocean review Strzepek et al. 212 Polar organisms Thalassiosira weissflogii Fe- limited, Irradiance = 7 μe 4 o C warming Irradiance increase to 11 μe Temperate Q1 equates to Q4 for polar waters Net estimated increase in IUE 3% Warming estimate: 22% increase Mixed layer shoaling estimate: 8% increase S- Table 1. Details of the calculation of an estimated future Iron Use Efficiency (IUE, kmols C fixed/mol cellular Fe/day) increase with 4 o C warming and 57% increase in irradiance (due to mixed layer shoaling) for polar diatoms, based on extrapolation of a lab culture study on temperate diatoms (Sunda and Huntsman 211) and one on polar and temperate diatoms (Strzepek et al., 212). The following assumptions were made: 1) Temperate diatoms will respond to light and warming in the same way as Southern Ocean diatoms; 2) T. pseudonana can be compared to T. weissflogii; 3) Q1 in temperate diatoms is equivalent to Q4 in polar species (Clarke 1983), 4) Effects of warming and irradiance on IUE are additive.

III. Supplementary Notes References for Supplementary Figures and Table Wells M.L., Manipulating iron availability in nearshore waters. Limnol Oceanogr., 44, 12 774 18 775, (1999) Hutchins, D.A., C.E. Hare, R.S. Weaver, Y. Zhang, G.F. Firme, et al., Phytoplankton iron limitation in the Humboldt Current and Peru Upwelling. Limnol. Oceanogr., 47, 997-111, (22). Boyd, P. W., Jickells, T., Law, C. S., Blain, S., Boyle, E. A., et al., Mesoscale iron enrichment experiments 1993-25: Synthesis and future directions. Science, 315, 612-617. doi: 1.1126/science.1131669, (27). Wilhelm, S. W., King, A. L., Twining, B. S., LeCleir, G. R., DeBruyn, et al. Elemental quotas and physiology of a southwestern Pacific Ocean plankton community as a function of iron availability. Aq. Micr. Ecol., 68, 185-194, doi: 1.3354/ame1611. (213). Fu, F.- X., Mulholland, M.R., Garcia, N., Beck, A., Bernhardt, P.W. et al., Interactions between changing pco 2, N 2 fixation, and Fe limitation in the marine unicellular cyanobacterium Crocosphaera. Limnol. Oceanogr. 53, 2472-2484, (28). Sunda, W.G. and Huntsman, S.A. Interactive effects of light and temperature on iron limitation in a marine diatom: Implications for marine productivity and carbon cycling. Limnol. Oceanogr., 56, 1475 1488, (211). Clarke, A. Life in cold water: the physiological ecology of polar marine ectotherms. Oceanogr. Mar Biol. Annu. Rev., 21, 341 453, (1983). Strzepek R., Maldonado M., Hunter K., Frew R., Boyd P.W., Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: uptake of organically complexed iron and reduced cellular iron requirements. Limnol Oceanogr., 56, 1983 22. doi: 1.4319/lo.211.56.6.1983, (212).