[en] Daily changes in the concentrations of carbon and nitrogen species were monitored during the course of a Lagrangian
drifter experiment in a recurrent upwelling filament south of Cape Finisterre (NW Iberian Upwelling System). A drifting
buoy released at the southern edge of the upwelling centre generated by the Cape moved 60km southwestwards from
3 to 7 August 1998. Organic matter in the 50m deep study water mass (average 77±2 μM C) consisted of: 57μM C
of dissolved organic matter (DOM) with a C/N molar ratio of 19±2; 6μM C of DOM with a C/N ratio of 9±2, and
14μM C of 50% DOM and 50% suspended organic matter (POMsusp) with a C/N ratio of 6.0±0.4.
Net conversion of consumed inorganic salts into accumulated TOM=POMsusp+DOM was 40% for nitrogen and
30% for carbon. Since the parcel of water crossed the shelf-edge, these conversion efficiencies are equivalent to net
horizontal export-ratio of 0.4 and 0.3 respectively. A second drifter was deployed in the offshore-end of the filament,
and was displaced 20km west between 14 and 17 August 1998. Nitrate was exhausted in the surface water and no
significant changes were observed in the variables measured during the course of the second experiment. Low C/N
ratios (6.5±0.4) and rapid POMsusp/DOM inter-conversion in the 20 μM C excess observed in the study volume points
to the persistence of the labile materials formed on the shelf during transport to the ocean. Our data demonstrate
a) the key role of upwelling filaments in off-shelf export of organic materials and
b) the major contribution of DOM to this horizontal export, a previously unaccounted amount.
Disciplines :
Aquatic sciences & oceanology
Author, co-author :
Alvarez-Salgado, Xosé Antón; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Abbott M.R., Brink K.H., Booth C.R., Blasco D., Codispoti L.A., Niiler P.P., Ramp S.R. (1990) Observations of phytoplankton and nutrients from a Lagrangian drifter off Northern California. Journal of Geophysical Research 95:9393-9409.
Álvarez-Salgado X.A., Rosón G., Pérez F.F., Pazos Y. (1993) Hydrographic variability off the Rías Baixas (NW Spain) during the upwelling season. Journal of Geophysical Research 98:14447-14455.
Álvarez-Salgado X.A., Miller A.E.J. (1998) Simultaneous determination of dissolved organic carbon and total dissolved nitrogen in seawater by high temperature catalytic oxidation: Conditions for accurate shipboard measurements. Marine Chemistry 62:325-333.
Álvarez-Salgado X.A., Doval M.D., Pérez F.F. (1999) Dissolved organic matter in shelf waters off the Ría de Vigo (NW Iberian upwelling system). Journal of Marine Systems 18:383-394.
Anderson L.A. (1995) On the hydrogen and oxygen content of marine phytoplankton. Deep-Sea Research I 42:1675-1680.
Archer D., Peltzer E.T., Kirchman D.L. (1997) A time-scale for dissolved organic carbon production in the equatorial Pacific surface water. Global Biogeochemicat Cycles 11:435-452.
Barton E.D., Arístegui J., Tett P., Cánton M., García-Braun J., Hernández-León S., Nykjaer L., Almeida C., Almunia J., Ballesteros S., Basterretxea G., Escáinez J., García-Weill L., Hernández-Guerra A., López-Laatzen F., Molina R., Montero M.F., Navarro-Pérez E., Rodríguez J.M., Van Lenning K., Vélez H., Wild K. (1998) The transition zone of the Canary Current upwelling region. Progress in Oceanography 41:455-504.
Bauer J.E., Druffel E.R.M. (1998) Ocean margins as a significant source of organic matter to the deep open ocean. Nature, London 392:482-485.
Biscaye P.E., Flagg C.N., Falkowski P.G. (1994) The Shelf Edge Exchange Processes experiment, SEEP-II: An introduction to hypothesis, results and conclusions. Deep-Sea Research II 41:231-252.
Bode A., Casas B., Fernández E., Marañon E., Serret P., Varela M. (1996) Phytoplankton biomass and production in shelf waters off NW Spain: Spatial and seasonal variability in relation to upwelling. Hydrobiotogia 341:225-234.
Brewer P.G., Riley J.P. (1965) The automatic determination of nitrate in seawater. Deep-Sea Research 12:765-772.
Brink K.H., Cowles T.J. (1991) The coastal transition zone program. Journal of Geophysical Research 96:14367-14648.
Broecker W.S., Peng T.-H. Tracers in the sea, New York: Eldigio Press; 1982.
Bronk D.A., Glibert P.M., Ward B.B. (1994) Nitrogen uptake, dissolved organic nitrogen release, and new production. Science 265:1843-1846.
Chavez F.P., Toggweiler J.R. (1995) Physical estimates of global new production: The upwelling contribution. Upwelling in the ocean. Modern processes and ancient records , C.P. Summerhayes, K.-C. Emeis, M.V. Angel, R.L. Smith, & B. Zeitzschel (Eds.). New York: Wiley and Sons; 13-32.
Cushing D.H. (1989) A difference in structure between ecosystems in strongly stratified water and in those that are weakly stratified. Journal of Plankton Research 2:1-13.
Del Giorgio P.A., Cole J.J., Cimbleris A. (1997) Respiration rates in bacteria exceed plankton production in unproductive aquatic systems. Nature 385:148-151.
Dickson A.G. (1990) Standard potential of the reaction: AgCl(s)+l/2H2(g)=Ag(s)+HCl(aq), and the standard acidity constant of the ion HSO4 in synthetic sea water from 273.15 to 318.15 K. Journal of Chemical Thermodynamics 22:113-127.
Dickson A.G. (1993) pH buffers for sea water media based on the total hydrogen ion concentration scale. Deep-Sea Research I 40:107-118.
Duarte C.M., Agustí S. (1998) The CO2 balance of unproductive aquatic ecosystems. Science 281:234-236.
Dugdale R.C., Wilkerson F.P. (1989) New production in the upwelling center at Point Conception, California: Temporal and spatial patterns. Deep-Sea Research 36:985-1007.
Falkowski P.G., Flagg C.N., Rowe G.T., Smith S.L., Whitledge T.E., Wirick C.D. (1988) The fate of a spring phytoplankton bloom: Export or oxidation?. Continental Shelf Research 8:457-484.
Fuhrman J.A. (1992) Bacterioplankton roles in cycling of organic matter: The microbial food web. Primary productivity and biogeochemical cycles in the sea , P. G. Falkowski, & A. D. Woodhead (Eds.). New York: Plenum Press; 361-383.
Gabric A.J., García L., Camp L.V., Nykjaer L., Eifler W., Schrimpf W. (1993) Offshore export of shelf production in the Cape Blanc (Mauritania) giant filament as derived from coastal zone colour scanner imagery. Journal of Geophysical Research 98:4697-4712.
Gabric A.J., Eifler W., Schrimpf W. (1996) A Lagrangian model of phytoplankton dynamics in the northwest African coastal upwelling zone. Advances in Space Research 18:99-115.
Garside C. (1981) Nitrate and ammonium uptake in the apex of the New York Bight. Limnology and Oceanography 26:731-739.
Grasshoff K. Methods of seawater analysis, Weiheim: Verlag Chemie; 1976.
Hansell D.A., Bates N.R., Gundersen K. (1995) Mineralization of dissolved organic carbon in the Sargasso Sea. Marine Chemistry 51:201-212.
Hansell D.A., Carlson C.A. (1998) Net community production of dissolved organic carbon. Global Biogeochemicat Cycles 12:443-453.
Hansson I., Jagner D. (1973) Evaluation of the accuracy of Gran plots by means of computer calculations. Anatytica Chimica Acta 65:363-373.
Haynes R., Barton E.D., Pilling I. (1993) Development, persistence and variability of upwelling filaments off the Atlantic Coast of the Iberian Peninsula. Journal of Geophysical Research 98:22681-22692.
Holm-Hansen O., Lorenzen C.J., Holmes R.W., Strickland J.D.H. (1965) Fluorometric determination of chlorophyll. Journal du Conseit Permanent International pour l'Exploration de la Mer 30:3-15.
Hood R., Abbott M., Huyer A., Kosro P. (1990) Surface patterns in temperature, flow, phytoplankton biomass and species composition in the coastal transition zone off northern California. Journal of Geophysical Research 95:18081-18094.
Joint I., Inall M., Torres R., Figueiras F.G., Álvarez-Salgado X.A., Rees A.P., Woodward M. (2001) Two Lagrangian experiments in the Iberian upwelling system: Tracking an upwelling event and an off-shore filament. Progress in Oceanography 51(2-4):221-248.
Jones B.H., Brink K.H., Dugdale R.C., Stuart D.W., Van Leer J.C., Blasco D., Kelly J.C. (1983) Observations of a persistent upwelling center off Point Conception, California. Coastal upwelling: its sediment record. Responses of the sedimentary regime to present coastal upwelling , E. Suess, & J. Thiede (Eds.). Plenum Press; 37-60.
Jones B.H., Morrers C.N.K., Reinecker M.M., Stanton T., Washburn L. (1991) Chemical and biological structure and transport of a cool filament associated with a jet-eddy system off Northern California in July 1986 (OPTOMA21). Journal of Geophysical Research 96:22207-22225.
Jones R.D. (1991) An improved fluorescence method for the determination of nanomolar concentrations of ammonium in natural waters. Limnology and Oceanography 36:814-819.
Kadko D.C., Washburn L., Jones B. (1991) Evidence of subduction within the cold filaments of the northern California coastal transition zone. Journal of Geophysical Research 96:14909-14926.
Kirchman D.L., Suzuki Y., Garside C., Ducklow H.W. (1991) High turnover rates of dissolved organic carbon during a spring phytoplankton bloom. Nature 352:612-614.
Kirchman D.L., Lancelot C., Fasham M., Legendre L., Radach G., Scott M. (1993) Dissolved organic material in biogeochemical models of the ocean. Towards a model of ocean biogeochemical processes. NATO series I: Global environmental change , G. T. Evans, & M. J. R. Fasham (Eds.). Berlin: Springer; 10:209-225.
Kirkwood D.S. (1989) Simultaneous determination of selected nutrients in seawater. ICES CM C(29).
Legendre L., Le Fèvre J. (1995) Microbial food webs and the export of biogenic carbon in the oceans. Aquatic Microbial Ecology 9:69-77.
MacIsaac J.J., Dugdale R.C., Barber R.T., Blasco D., Packard T.T. (1985) Primary production cycle in an upwelling center. Deep-Sea Research 32:503-529.
Mantoura R.F.C., Woodward E.M.S. (1983) Optimization of the indophenol blue method for the automated determination of ammonia in estuarine waters. Estuarine, Coastal and Shelf Science 17:219-224.
Moisan J.R., Hofmann E.E., Haidvogel D.B. (1996) Modelling nutrient and plankton processes in the California coastal transition zone 2. A three-dimensional physical-bio-optical model. Journal of Geophysical Research 101:22677-22691.
Moisan J.R., Hofmann E.E. (1996) Modelling nutrient and plankton processes in the California coastal transition zone 3. Lagrangian drifters. Journal of Geophysical Research 101:22677-22691.
Moran M.A., Zepp R.G. (1997) Role of photoreactions in the formation of biologically labile compounds from dissolved organic matter. Limnology and Oceanography 42:1307-1316.
Nogueira E., Pérez F.F., Rios A.F. (1997) Seasonal patterns and long-term trends in an estuarine upwelling ecosystem (Ría de Vigo, NW Spain). Estuarine, Coastal and Shelf Science 44:285-300.
Norrman B., Zweifel U.L., Hopkinson C.S., Fry B. (1995) Production and utilisation of dissolved organic carbon during an experimental diatom bloom. Limnology and Oceanography 40:898-907.
Olli K., Wexels Riser C., Wassmann P., Ratkova A., Arashkevich E., Pastemak A. (2001) Vertical flux of biogenic matter during a Lagrangian study off the NW Spanish continental margin. Progress in Oceanography 51(2-4):443-466.
Parsons T.R., Malta Y., Lalli C.M. A manual of chemical and biological methods for sea-water analysis, Pergamon: Oxford; 1984.
Pérez F.F., Mouriño C., Fraga F., Ríos A.F. (1993) Displacement of water masses and remineralization rates off the Iberian Peninsula by nutrient anomalies. Journal of Marine Research 51:869-892.
Roy R.N., Roy L.N., Vogel K.M., Porter-Moore C., Pearson T., Good C.E., Millero F.J., Cambell D.J. (1993) Determination of the ionization constants of carbonic acid in seawater in salinities 5 to 45 and temperatures 0 to 45°C. Marine Chemistry 44:249-267.
Sokal R.R., Rohlf F.J. Biometry, New York: Freeman and Company; 1995.
Søndergaard M., Williams P.J.L.B., Cauwet G., Riemann B., Robinson C., Terzic S., Woodward E.M.S., Worm J. (2000) Net accumulation and flux of dissolved organic carbon and dissolved organic nitrogen in marine plankton communities. Limnology and Oceanography 45:1097-1111.
Strub P.T., Kosro P.M., Huyer A. (1991) The nature of cold filaments in the California Current system. Journal of Geophysical Research 96:14743-14768.
Swenson M.S., Niiler P.P., Brink K.H., Abbott M.R. (1992) Drifter observations of a cold filament off Point Arena, California, in July 1988. Journal of Geophysical Research 97:3593-3610.
Thingstad T.F., Hagström A., Rassoulzadegan F. (1997) Accumulation of degradable DOC in surface waters: Is it caused by a malfunctioning microbial loop?. Limnotogy and Oceanography 42:398-404.
Traganza E.D., Conrad J.C., Braker L.C. (1981) Satellite observations of a cyclonic upwelling system and a giant plume in the California Current. Coastal upwelling, coastal estuarine science , F. A. Richards (Eds.). Washington: AGU; 1:228-241.
Progress on oceanographic tables and standards 1983-1986. Work and recommendations of the UNESCO/SCOR/ICES/IAPSO Joint Panel , UNESCO Technical Papers in Marine Sciences; 1986, 50.
Vidal M., Duarte C.M., Agustí S. (1999) Dissolved organic nitrogen and phosphorus pools and fluxes in the central Atlantic Ocean. Limnology and Oceanography 44:106-117.
Wafar M.V.M., Le Corre P., L'helguen S. (1995) F-ratios calculated with and without urea uptake in nitrogen uptake by phytoplankton. Deep-Sea Research I 9:1669-1674.
Walsh J.J., Rowe G.T., Iverson R.L., McRoy C.P. (1981) Biological export of shelf carbon: A neglected sink of the global CO2 cycle. Nature 291:196-201.
Walsh J.J. (1991) Importance of continental margins in the marine biogeochemical cycling of carbon and nitrogen. Nature 359:53-55.
Wilkerson F.P., Dugdale R.C. (1987) The use of large shipboard barrels and drifters to study the effect of coastal upwelling on phytoplankton nutrient dynamics. Limnology and Oceanography 32:368-382.
Williams P.J.L.B. (1995) Evidence for the seasonal accumulation of carbon-rich dissolved organic material, its scale in comparison with changes in particulate material and the consequential effect on net C/N assimilation ratios. Marine Chemistry 51:17-29.
Williams P.J.L.B. (1998) The balance of plankton respiration and photosynthesis in the open oceans. Nature 394:55-57.
Wollast R. (1998) Evaluation and comparison of the global carbon cycle in the coastal zone and in the open ocean. The sea , K. H. Brink, & A. R. Robinson (Eds.). New York: John Wiley and Sons; 10:213-252.
Wooster W.S., Bakun A., McClain D.R. (1976) The seasonal upwelling cycle along the eastern boundary of the North Atlantic. Journal of Marine Research 34:131-141.
Yamanaka Y., Tajika E. (1997) Role of dissolved organic matter in the marine biogeochemical cycle: Studies using an ocean biogeochemical general circulation model. Global Biogeochemical Cycles 11:599-612.