Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 5 1 2008 10.5194/bg-5-133-2008 http://www.biogeosciences.net/5/133/2008/ http://www.biogeosciences.net/5/133/2008/bg-5-133-2008.html http://www.biogeosciences.net/5/133/2008/bg-5-133-2008.pdf 133 139 2008-02-06 Phospholipid synthesis rates in the eastern subtropical South Pacific Ocean B. A. S. Van Mooy bvanmooy@whoi.edu T. Moutin S. Duhamel P. Rimmelin F. Van Wambeke Dept. of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, MS #4, Woods Hole, MA 02543, USA Laboratoire d'Océanographie et de Biogéochimie, UMR-CNRS 6535, Case 901, Centre d'Océanologie de Marseille, Université de la Méditerranée – Campus de Luminy, 13 288 Marseille cedex 9, France Laboratoire de Microbiologie, Géochimie et Ecologie Marines, UMR-CNRS 6117, Case 901, Centre d'Océanologie de Marseille, Université de la Méditerranée – Campus de Luminy, 13 288 Marseille Cedex 9, France Membrane lipid molecules are a major component of planktonic organisms and this is particularly true of the microbial picoplankton that dominate the open ocean; with their high surface-area to volume ratios, the synthesis of membrane lipids places a major demand on their overall cell metabolism. Specifically, the synthesis of cell membrane phospholipids creates a demand for the nutrient phosphorus, and we sought to refine our understanding of the role of phospholipids in the upper ocean phosphorus cycle. We measured the rates of phospholipid synthesis in a transect of the eastern subtropical South Pacific from Easter Island to Concepcion, Chile as part of the BIOSOPE program. Our approach combined standard phosphorus radiotracer incubations and lipid extraction methods. We found that phospholipid synthesis rates varied from less than 1 to greater than 200 pmol P L^−1 h^−1, and that phospholipid synthesis contributed between less than 5% to greater than 22% of the total PO₄^3− incorporation rate. Changes in the percentage that phospholipid synthesis contributed to total PO₄^3− uptake were strongly correlated with the ratio of primary production to bacterial production, which supported our hypothesis that heterotrophic bacteria were the primary agents of phospholipid synthesis. The spatial variation in phospholipid synthesis rates underscored the importance of heterotrophic bacteria in the phosphorus cycle of the eastern subtropical South Pacific, particularly the hyperoligotrophic South Pacific subtropical gyre. Bell, M. V. and Pond, D.: Lipid composition during growth of motile and coccolith forms of Emiliania huxleyi, Phytochemistry, 41, 465–471, 1996. Benning, C.: Biosynthesis and function of the sulfolipid sulfoquinovosyl diacylglycerol, Annu. Rev. Plant Physiol. Plant Mol. Biol., 49, 53–75, 1998. Björkman, K., Thomson-Bulldis, A. L., and Karl, D. M.: Phosphorus dynamics in the North Pacific subtropical gyre, Aquat. Microb. Ecol., 22, 185–198, 2000. Bligh, E. G. and Dyer, W. J.: A rapid method of total lipid extraction and purification, Can. J. Biochem. Physiol., 37, 911–917, 1959. Bonnet, S., Guieu, C., Bruyant, F., Prasil, O., Raimbault, P., Van Wambeke, F., Gorbunov, M., Zehr, J. P., Grob, C., Masquelier, S., Garczareck, L., and Claustre, H.: Nutrients controlling primary productivity in the South East Pacific (BIOSOPE cruise), Biogeosciences Discuss., 4, 2733–2759, 2007. Campbell, L. and Vaulot, D.: Photosynthetic Picoplankton Community Structure in the Subtropical North Pacific-Ocean near Hawaii (Station Aloha), Deep-Sea Res. I, 40, 2043–2060, 1993. Campbell, L., Nolla, H. A., and Vaulot, D.: The importance of \textitProchlorococcus to community structure in the central north Pacific Ocean, Limnol. Oceanogr., 39, 954–961, 1994. Campbell, L., Liu, H., Nolla, H. A., and Vaulot, D.: Annual variability of phytoplankton and bacteria in the subtropical North Pacific Ocean at Station ALOHA during the 1991-1994 ENSO event, Deep-Sea Res I, 44, 167–192, 1997. Cavender-Bares, K. K., Karl, D. M., and Chisholm, S. W.: Nutrient gradients in the western North Atlantic Ocean: Relationship to microbial community stucture and comparison to patterns in the Pacific Ocean, Deep-Sea Res I, 48, 2373–2395, 2001. Cho, B. C. and Azam, F.: Biogeochemical significance of bacterial biomass in the ocean's euphotic zone, Mar. Ecol. Prog. Ser., 63, 253–259, 1990. Cuhel, R. L. and Waterbury, J. B.: Biochemical composition and short term nutrient incorporation patterns in a unicellular marine cyanobacterium, Synechococcus (WH7803), Limnol. Oceanogr., 29, 370–374, 1984. Deutsch, C., Sarmiento, J. L., Sigman, D. M., Gruber, N., and Dunne, J. P.: Spatial coupling of nitrogen inputs and losses in the ocean, Nature, 445, 163–167, 2007. Duhamel, S., Zeman, F., and Moutin, T.: A dual-labeling method for the simultaneous measurement of dissolved inorganic carbon and phosphate uptake by marine planktonic species, Limnol. Oceanogr. Meth., 4, 416–425, 2006. Duhamel, S., Moutin, T., Van Wambeke, F., Van Mooy, B., Rimmelin, P., Raimbault, P., and Claustre, H.: Growth and specific P-uptake rates of bacterial and phytoplanktonic communities in the Southeast Pacific (BIOSOPE cruise), Biogeosciences, 4, 913–925, 2007. Grob, C., Ulloa, O., Claustre, H., Huot, Y., Alarcón, G., and Marie, D.: Contribution of picoplankton to the total particulate organic carbon concentration in the eastern South Pacific, Biogeosciences, 4, 837–852, 2007. Kato, M., Sakai, M., Adachi, K., Ikemoto, H., and Sano, H.: Distribution of betain lipids in marine algae, Phytochemistry, 42, 1341–1345, 1996. Moutin, T., Thingstad, T. F., Wambeke, V., Marie, D., Slawyk, G., Raimbault, P., and Claustre, H.: Does competition for nanomolar phosphate supply explain the predominance of the cyanobacterium Synechococcus?, Limnol. Oceanogr., 47, 1562–1567, 2002. Moutin, T., Karl, D. M., Duhamel, S., Rimmelin, P., Raimbault, P., Van Mooy, B. A. S., and Claustre, H.: Phosphate availability and the ultimate control of new nitrogen input by nitrogen fixation in the tropical Pacific Ocean, Biogeosciences, 5, 95–109, 2008. Thingstad, T. F., Krom, M. D., Mantoura, R. F. C., Flaten, G. A. F., Groom, S., Herut, B., Kress, N., Law, C. S., Pasternak, A., Pitta, P., Psarra, S., Rassoulzadegen, F., Tanaka, T., Tselepides, A., Wassman, P., Woodward, E. M. S., Wexels Riser, C., Zodiatis, G., and Zohary, T.: Nature of phosphorus limitation in the ultraoligotrophic eastern Mediterranean, Science, 309, 1068–1071, 2005. Van Mooy, B. A. S., Rocap, G., Fredricks, H. F., Evans, C. T., and Devol, A. H.: Sulfolipids dramatically decrease phosphorus demand by picocyanobacteria in oligotrophic marine environments, Proc. Natl. Acad. Sci., 103, 8607–8612, 2006. Van Mooy, B. A. S. and Devol, A. H.: Assessing nutrient limitation of Prochlorococcus at ALOHA by using an RNA capture method, Limnol. Oceanogr., 53, 78–88, 2008. Van Wambeke, F., Obernosterer, I., Moutin, T., Duhamel, S., Ulloa, O., and Claustre, H.: Heterotrophic prokaryotic production in the South East Pacific: Longitudinal trends and coupling with primary production, Biogeosciences Discuss., 4, 2761–2791, 2007a. Van Wambeke, F., Bonnet, S., Moutin, T., Raimbault, P., Alarçon G., and Guieu, C.: Factors limiting heterotrophic prokaryotic production in the southern Pacific Ocean, Biogeosciences Discuss., 4, 3799–3828, 2007b. Wada, H. and Murata, N.: Membrane lipids in cyanobacteria. Lipids in photosynthesis: structure, function and genetics, edited by: Siegenthaler, P.-A. and Murata, N., Kluwer Academic, 65–81, 1998. Wakeham, S. G., Hedges, J. I., Lee, C., Peterson, M. L., and Hernes, P. J.: Compositions and transport of lipid biomarkers through the water column and surficial sediments of the equatorial Pacific Ocean, Deep-Sea Res II, 44, 2131–2162, 1997.