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Dynamics of dissolved and biogenic silica in the freshwater reaches of a macrotidal estuary (The Scheldt, Belgium)

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Abstract

Temporal evolution of dissolved and biogenic silica concentrations along the Scheldt tidal river and in its tributaries was investigated during 1 year in 2003. In the tributaries, dissolved silica (DSi) concentrations remained high and biogenic silica (BSi) concentrations were low throughout the year. In the tidal river during summer, DSi was completely consumed and BSi concentrations increased. Overall, most of the BSi was associated with living diatoms during the productive period in the tidal river. Nevertheless, the detrital BSi was a significant fraction of the total BSi pool, of which less than 10% could be attributed to phytoliths. The tidal river was divided into two zones for budgeting purposes. The highest productivity was observed in the zone that received the highest water discharge, as higher riverine DSi input fluxes induced presumably a less restrictive DSi limitation, but the discharge pattern could not explain all by itself the variations in DSi consumption. Silica uptake and retention in the tidal river were important at the seasonal time-scale: from May to September, 48% of the riverine DSi was consumed and 65% of the produced BSi was deposited, leading to a silica (DSi + BSi) retention in the tidal river of 30%. However, when annual fluxes were considered, DSi uptake in the tidal river amounted to 14% of the DSi inputs and only 6% of the riverine silica (DSi + BSi) was retained in the tidal river.

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Abbreviations

BSi:

Biogenic silica

BSidet :

BSi not associated with living diatoms

BSiliv :

BSi associated with living diatom

DiatChla :

Chlorophyll a ascribed to diatoms

DSi:

Dissolved silica

POC:

Particulate organic carbon

POCnld :

POC not corresponding to living diatoms

SPM:

Suspended particulate matter

SPMnbld :

SPM not corresponding to BSi nor to living diatoms

References

  • Abril G, Nogueira M, Etcheber H, Cabeçadas G, Lemaire E, Brogueira MJ (2002) Behaviour of organic carbon in nine contrasting European estuaries. Estuar Coast Shelf Sci 54:241–262

    Article  Google Scholar 

  • Admiraal W, Breugem P, Jacobs DMLHA, de Ruyter van Steveninck ED (1990) Fixation of dissolved silicate and sedimentation of biogenic silicate in the lower river Rhine during diatom blooms. Biogeochemistry 9:175–185

    Article  Google Scholar 

  • Alexandre A, Meunier J-D, Colin F, Koud J-M (1997) Plant impact on the biogeochemical cycle of silicon and related weathering processes. Geochim Cosmochim Acta 61(3):677–682

    Article  Google Scholar 

  • Anderson GF (1986) Silica, diatoms and a freshwater productivity maximum in Atlantic coastal plain estuaries, Chesapeake Bay. Estuar Coast Shelf Sci 22:183–197

    Article  Google Scholar 

  • Arndt S, Regnier P (2007) A model for the benthic-pelagic coupling of silica in estuarine ecosystems: sensitivity analysis and system scale simulation. Biogeosciences 4:331–352

    Google Scholar 

  • Arndt S, Vanderborght J-P, Regnier P (2007) Diatom growth response to physical forcing in a macrotidal estuary: coupling hydrodynamics, sediment transport, and biogeochemistry. J Geophys Res 112:C05045

    Article  Google Scholar 

  • Bidle KD, Azam F (1999) Accelerated dissolution of diatom silica by marine bacterial assemblages. Nature 397:508–512

    Article  Google Scholar 

  • Blecker SW, McCulley RL, Chadwick OA, Kelly EF (2006) Biologic cycling of silica across a grassland bioclimosequence. Glob Biogeochem Cycle 20:GB3023

    Article  Google Scholar 

  • Bouezmarni M, Wollast R (2005) Geochemical composition of sediments in the Scheldt estuary with emphasis on trace metals. Hydrobiologia 540(1–3):155–168

    Article  Google Scholar 

  • Carbonnel V (2009) Silica dynamics and retention in the Scheldt tidal river and estuary (Belgium/The Netherlands). Ph. D. thesis, Université Libre de Bruxelles, Belgium

  • Cary L, Alexandre A, Meunier J-D, Boeglin J-L, Braun J-J (2005) Contribution of phytoliths to the suspended load of biogenic silica in the Nyong basin rivers (Cameroon). Biogeochemistry 74:101–104

    Article  Google Scholar 

  • Chen MS, Wartel S, Van Eck B, Van Maldegem D (2005a) Suspended matter in the Scheldt estuary. Hydrobiologia 540(1–3):79–104

    Article  Google Scholar 

  • Chen MS, Wartel S, Temmerman S (2005b) Seasonal variation of floc characteristics on tidal flats, the Scheldt estuary. Hydrobiologia 540(1–3):181–195

    Article  Google Scholar 

  • Conley DJ (1997) Riverine contribution of biogenic silica to the oceanic silica budget. Limnol Oceanogr 42(4):774–777

    Google Scholar 

  • Conley DJ (2002) Terrestrial ecosystems and the global biogeochemical silica cycle. Glob Biogeochem Cycle 16(4):68(1)–68(7)

    Article  Google Scholar 

  • Conley DJ, Schelske CL, Stoermer EF (1993) Modification of the biogeochemical cycle of silica with eutrophication. Mar Ecol Prog Ser 101:179–192

    Article  Google Scholar 

  • Conley DJ, Likens GE, Buso DC, Saccone L, Bailey SW, Johnson CE (2008) Deforestation causes increased dissolved silicate losses in the Hubbard Brook Experimental Forest. Glob Change Biol 14(11):2548–2554

    Google Scholar 

  • Cushing DH (1989) A difference in structure between ecosystems in strongly stratified waters and in those that are only weakly stratified. J Plankton Res 11(1):1–13

    Article  Google Scholar 

  • Dagnelie P (1973) Théorie et méthodes statistiques, vol 1. Presses agronomiques de Gembloux, Gembloux (In French)

    Google Scholar 

  • Dagnelie P (2006) Statistique théorique et appliquée. Vol. 2, inférence statistique à une et à deux dimensions, 2e édition. Editions De Boeck Université, Bruxelles (In French)

    Google Scholar 

  • Datnoff LE, Snyder GH, Korndorfer GH (eds) (2001) Silicon in agriculture. Studies in plant science 8. Elsevier Science

  • De Sève MA (1993) Diatom bloom in the tidal freshwater zone of a turbid and shallow estuary, Rupert Bay (James Bay, Canada). Hydrobiologia 269/270:225–233

    Article  Google Scholar 

  • Delstanche S (2004) Contribution à l’étude du cycle biogéochimique de la silice dans le continuum aquatique de l’Escaut. MSc. thesis, Université Catholique de Louvain, Belgium (In French)

  • Derry LA, Kurtz AC, Ziegler K, Chadwick OA (2005) Biological control of terrestrial silica cycling and export fluxes to watersheds. Nature 433:728–731

    Article  Google Scholar 

  • Dougan WK, Wilson AL (1974) The absorptiometric determination of aluminium in water. A comparison of some chromogenic reagents and the development of an improved method. Analyst 99:413–430

    Article  Google Scholar 

  • Garnier J, d’Ayguesvives A, Billen G, Conley DJ, Sferratore A (2002) Silica dynamics in the hydrographic network of the Seine River. Océanis 28(3–4):487–508

    Google Scholar 

  • Geider RJ (1987) Light and temperature dependence of the carbon to chlorophyll a ratio in microalgae and cyanobacteria: implications for physiology and growth of phytoplankton. New Phytol 106:1–34

    Article  Google Scholar 

  • Hellings L, Dehairs F, Tackx M, Keppens E, Baeyens W (1999) Origin and fate of organic carbon in the freshwater part of the Scheldt Estuary as traced by stable carbon isotope composition. Biogeochemistry 47:167–186

    Google Scholar 

  • Hildebrand M (2002) Lack of coupling between silicon and other elemental metabolisms in diatoms. J Phycol 38:841–843

    Article  Google Scholar 

  • Humborg C, Pastuszak M, Aigars J, Siegmund H, Mörth C-M, Ittekot V (2006) Decreased silica land-sea fluxes through damming in the Baltic Sea catchment—significance of particle trapping and hydrological alterations. Biogeochemistry 77:265–281

    Article  Google Scholar 

  • IRMB (Institut Royal Météorologique de Belgique) (2003–2004) Bulletins mensuels, Observations climatologiques, parties I et II. Institut Royal Météorologique de Belgique, Bruxelles (In French/Dutch)

  • Jacobs S, Struyf E, Maris T, Meire P (2008) Spatiotemporal aspects of silica buffering in restored tidal marshes. Estuar Coast Shelf Sci 80(1):42–52

    Article  Google Scholar 

  • Kamatani A, Oku O (2000) Measuring biogenic silica in marine sediments. Mar Chem 68(3):219–229

    Article  Google Scholar 

  • Koroleff F (1983) Determination of silicon. In: Grasshoff K, Ehrhardt M, Kremling K (eds) Methods of seawater analysis. Second, revised and extended edition. Verlag Chemie, Deerfield Beach, pp 174–187

    Google Scholar 

  • Kronvang B, Bruhn AJ (1996) Choice of sampling strategy and estimation method for calculating nitrogen and phosphorus transport in small lowland streams. Hydrol Process 10:1483–1501

    Article  Google Scholar 

  • Lancelot C (1995) The mucilage phenomenon in the continental coastal waters of the North Sea. Sci Total Environ 165(1–3):83–102

    Google Scholar 

  • Lionard M (2006) Spatio-temporal phytoplankton dynamics along the Scheldt-North Sea continuum based on HPLC/CHEMTAX pigment analysis. Ph. D. thesis, Univ. of Ghent, Belgium

  • Lionard M, Muylaert K, Tackx M, Vyverman W (2008a) Evaluation of the performance of HPLC-CHEMTAX analysis for determining phytoplankton biomass and composition in a turbid estuary (Schelde, Belgium). Estuar Coast Shelf Sci 76(4):809–817

    Article  Google Scholar 

  • Lionard M, Muylaert K, Hanouti A, Maris T, Tackx M, Vyverman W (2008b) Inter-annual variability in phytoplankton summer blooms in the freshwater tidal reaches of the Schelde estuary (Belgium). Estuar Coast Shelf Sci 79(4):694–700

    Article  Google Scholar 

  • Loucaides S, Van Cappellen P, Behrends T (2008) Dissolution of biogenic silica from land to ocean: role of salinity and pH. Limnol Oceanogr 53(4):1614–1621

    Google Scholar 

  • Mackey MD, Mackey DJ, Higgins HW, Wright SW (1996) CHEMTAX—a program for estimating class abundances from chemical markers: application to HPLC measurements of phytoplankton. Mar Ecol Prog Ser 144:265–283

    Article  Google Scholar 

  • Martin-Jézéquel V, Hildebrand M, Brzezinski MA (2000) Silicon metabolism in diatoms: implications for growth. J Phycol 36:821–840

    Article  Google Scholar 

  • McLusky DS (1993) Marine and estuarine gradients—an overview. Neth J Aquat Ecol 27(2–4):489–493

    Article  Google Scholar 

  • Meire P, Ysebaert T, Van Damme S, Van den Bergh E, Maris T, Struyf E (2005) The Scheldt estuary: a description of a changing ecosystem. Hydrobiologia 540(1–3):1–11

    Article  Google Scholar 

  • Moatar F, Meybeck M (2005) Compared performances of different algorithms for estimating annual nutrient loads discharged by the eutrophic River Loire. Hydrol Process 19:429–444

    Article  Google Scholar 

  • Moatar F, Meybeck M (2007) Riverine fluxes of pollutants: Towards predictions of uncertainties by flux duration indicators. C R Geosci 339:367–382

    Article  Google Scholar 

  • Moatar F, Person G, Meybeck M, Coynel A, Etcheber H, Crouzet P (2006) The influence of contrasting suspended particulate matter transport regimes on the bias and precision of flux estimates. Sci Total Environ 370:515–531

    Article  Google Scholar 

  • Muylaert K, Van Kerckvoorde A, Vyverman W, Sabbe K (1997) Structural characteristics of phytoplankton assemblages in tidal and non-tidal freshwater systems: a case study from the Schelde basin, Belgium. Freshw Biol 38:263–276

    Article  Google Scholar 

  • Muylaert K, Sabbe K, Vyverman W (2000) Spatial and temporal dynamics of phytoplankton communities in a freshwater tidal estuary (Schelde, Belgium). Estuar Coast Shelf Sci 50(5):673–687

    Article  Google Scholar 

  • Muylaert K, Van Wichelen J, Sabbe K, Vyverman W (2001) Effects of freshets on phytoplankton dynamics in a freshwater tidal estuary (Schelde, Belgium). Arch Hydrobiol 150(2):269–288

    Google Scholar 

  • Muylaert K, Tackx M, Vyverman W (2005) Phytoplankton growth rates in the freshwater tidal reaches of the Schelde estuary (Belgium) estimated using a simple light-limited primary production model. Hydrobiologia 540(1–3):127–140

    Article  Google Scholar 

  • Muylaert K, Gonzales R, Franck M, Lionard M, van der Zee C, Cattrijsse A, Sabbe K, Chou L, Vyverman W (2006) Spatial variation in phytoplankton dynamics in the Belgian coastal zone of the North Sea studied by microscopy, HPLC-CHEMTAX and underway fluorescence recordings. J Sea Res 55:253–265

    Article  Google Scholar 

  • Nelson DM, Tréguer P, Brzezinski MA, Leynaert A, Quéguiner B (1995) Production and dissolution of biogenic silica in the ocean: revised global estimates, comparison with regional data and relationship to biogenic sedimentation. Glob Biogeochem Cycle 9(3):359–372

    Article  Google Scholar 

  • Officer CB, Ryther JH (1980) The possible importance of silicon in marine eutrophication. Mar Ecol Prog Ser 3:83–91

    Article  Google Scholar 

  • Peterson DH, Smith RE, Hager SW, Harmon DD, Herndon RE, Schemel LE (1985) Interannual variability in dissolved inorganic nutrients in Northern San Francisco Bay Estuary. Hydrobiologia 129:37–58

    Article  Google Scholar 

  • Ploug H, Iversen MH, Koski M, Buitenhuis ET (2008) Production, oxygen respiration rates, and sinking velocity of copepod fecal pellets: direct measurements of ballasting by opal and calcite. Limnol Oceanogr 53(2):469–476

    Google Scholar 

  • Ragueneau O, Tréguer P, Leynaert A, Anderson RF, Brzezinski MA, DeMaster DJ, Dugdale RC, Dymond J, Fischer G, Francois R, Heinze C, Maier-Reimer E, Martin-Jézéquel V, Nelson DM, Quéguiner B (2000) A review of the Si cycle in the modern ocean: recent progress and missing gaps in the application of biogenic opal as a paleoproductivity proxy. Glob Planet Change 26(4):317–365

    Article  Google Scholar 

  • Ragueneau O, Savoye N, Del Amo Y, Cotten J, Tardiveau B, Leynaert A (2005) A new method for the measurement of biogenic silica in suspended matter of coastal waters: using Si:Al ratios to correct for the mineral interference. Cont Shelf Res 25(5–6):697–710

    Article  Google Scholar 

  • Reynolds CS (1988) Potamoplankton: paradigms, paradoxes and prognoses. In: Round FE (ed) Algae and the aquatic environment. Biopress, Bristom, pp 285–311

    Google Scholar 

  • Roubeix V, Becquevort S, Lancelot C (2008) Influence of bacteria and salinity on diatom biogenic silica dissolution in estuarine systems. Biogeochemistry 88(1):47–62

    Article  Google Scholar 

  • Schuchardt B, Schirmer M (1991) Phytoplankton maxima in the tidal freshwater reaches of two coastal plain estuaries. Estuar Coast Shelf Sci 32:187–206

    Article  Google Scholar 

  • Schuchardt B, Haesloop U, Schirmer M (1993) The tidal freshwater reach of the Weser Estuary: riverine or estuarine? Neth J Aquat Ecol 27(2–4):215–226

    Article  Google Scholar 

  • Sicko-Goad LM, Schelske CL, Stoermer EF (1984) Estimation of intracellular carbon and silica content of diatoms from natural assemblages using morphometric techniques. Limnol Oceanogr 29(6):1170–1178

    Google Scholar 

  • Soetaert K, Herman PMJ (1995) Estimating estuarine residence times in the Westerschelde (The Netherlands) using a box model with fixed dispersion coefficients. Hydrobiologia 311:215–224

    Article  Google Scholar 

  • Soetaert K, Hoffmann M, Meire P, Starink M, van Oevelen D, Van Regenmortel S, Cox T (2004) Modeling growth and carbon allocation in two reed beds (Phragmites australis) in the Scheldt estuary. Aquat Bot 79:211–234

    Article  Google Scholar 

  • Soetaert K, Middelburg JJ, Heip C, Meire P, Van Damme S, Maris T (2006) Long-term change in dissolved inorganic nutrients in the heterotrophic Scheldt estuary (Belgium, The Netherlands). Limnol Oceanogr 51(1, part 2):409–423

    Article  Google Scholar 

  • Struyf E, Van Damme S, Meire P (2004) Possible effects of climate change on estuarine nutrient fluxes: a case study in the highly nutrified Schelde estuary (Belgium, The Netherlands). Estuar Coast Shelf Sci 60(4):649–661

    Article  Google Scholar 

  • Struyf E, Van Damme S, Gribsholt B, Middelburg JJ, Meire P (2005) Biogenic silica in tidal freshwater marsh sediments and vegetation (Schelde estuary, Belgium). Mar Ecol Prog Ser 303:51–60

    Article  Google Scholar 

  • Struyf E, Dausse A, Van Damme S, Bal K, Gribsholt B, Boschker HTS, Middelburg JJ, Meire P (2006) Tidal marshes and biogenic silica recycling at the land-sea interface. Limnol Oceanogr 51(2):836–846

    Article  Google Scholar 

  • Struyf E, Van Damme S, Gribsholt B, Bal K, Beauchard O, Middelburg JJ, Meire P (2007a) Phragmites australis and silica cycling in tidal wetlands. Aquat Bot 87:134–140

    Article  Google Scholar 

  • Struyf E, Temmerman S, Meire P (2007b) Dynamics of biogenic Si in freshwater tidal marshes: Si regeneration and retention in marsh sediments (Scheldt estuary). Biogeochemistry 82:41–53

    Article  Google Scholar 

  • Suzumura M, Kokubun H, Arata N (2004) Distribution and characteristics of suspended particulate matter in a heavily eutrophic estuary, Tokyo Bay, Japan. Mar Pollut Bull 49:496–503

    Article  Google Scholar 

  • Temmerman S, Govers G, Wartel S, Meire P (2003) Spatial and temporal factors controlling short-term sedimentation in a salt and freshwater tidal marsh, Scheldt estuary, Belgium, SW Netherlands. Earth Surf Process Landf 28:739–755

    Article  Google Scholar 

  • Tréguer P, Pondaven P (2000) Silica control of carbon dioxide. Nature 406:358–359

    Article  Google Scholar 

  • Tréguer P, Nelson DM, Van Bennekom AJ, DeMaster DJ, Leynaert A, Quéguiner B (1995) The silica balance in the world ocean: a reestimate. Science 268:375–379

    Article  Google Scholar 

  • Turner RE, Qureshi N, Rabalais NN, Dortch Q, Justic’ D, Shaw RF, Cope J (1998) Fluctuating silicate:nitrate ratios and coastal plankton food webs. Proc Natl Acad Sci USA 95:13048–13051

    Article  Google Scholar 

  • Van Cappellen P, Dixit S, van Beusekom J (2002) Biogenic silica dissolution in the oceans: reconciling experimental and field-based dissolution rates. Glob Biogeochem Cycle 16(4):1075

    Article  Google Scholar 

  • Van Damme S, Struyf E, Maris T, Ysebaert T, Dehairs F, Tackx M, Heip C, Meire P (2005) Spatial and temporal patterns of water quality along the estuarine salinity gradient of the Scheldt estuary (Belgium and The Netherlands): results of an integrated monitoring approach. Hydrobiologia 540(1–3):29–45

    Article  Google Scholar 

  • Van der Zee C, Chou L (2005) Seasonal cycling of phosphorus in the Southern Bight of the North Sea. Biogeosciences 2:27–42

    Article  Google Scholar 

  • Van der Zee C, Roevros N, Chou L (2007) Phosphorus speciation, transformation and retention in the Scheldt estuary (Belgium/The Netherlands) from the freshwater tidal limits to the North Sea. Mar Chem 106(1–2):76–91

    Google Scholar 

  • Verbanck M, Vanderborght J-P, Wollast R (1994) Major ion content of urban wastewater: assessment of per capita loading. Res J Water Pollut Control Federation 61(11/12):1722–1728

    Google Scholar 

  • WLHO (Waterbouwkundig Laboratorium en Hydrologisch Onderzoek) (1966) Stormvloeden op de Schelde, parts 3 and 4. Borgerhout, Antwerp (In Dutch)

  • Wollast R (1974) The silica problem. In: Goldberg ED (ed) The sea, vol 5. Wiley, New York, pp 359–392

    Google Scholar 

  • Wright SW, Jeffrey SW (1997) High-resolution HPLC system for chlorophylls and carotenoids of marine phytoplankton. In: Jeffrey SW, Mantoura RFC, Wright SW (eds) Phytoplankton pigments in oceanography: guidelines to modern methods. UNESCO Publishing, Paris, pp 327–341

    Google Scholar 

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Acknowledgments

We are very grateful to Jean-Pierre Vanderborght for constructive discussions and comments on the manuscript. Claar van der Zee and Nathalie Roevros commented on previous versions of the manuscript. We would also like to thank Nathalie Roevros, Nicolas Canu, Renaat Dasseville, Christiane de Marneffe, Michaël Tsagaris and Stijn Vanneste for their assistance in field sampling and laboratory analyses. Victor Chepurnov isolated the Cyclotella sp. strains for the phytoplankton collection of the Ghent University. Data on water discharge were provided by the Ministry of the Flemish Community (Afdeling Maritieme Toegang). We would also like to thank the three anonymous reviewers for their constructive comments and suggestions. This study was financed by the Belgian Federal Science Policy Office (BELSPO) under contract number EV/11/17A (SISCO). Additional BELSPO funding from the TIMOTHY project (Interuniversity Attraction Pole, IAP, P6/13) is acknowledged. This is also a contribution to the EU IP CarboOcean (contract no. 511176–2). We would like to dedicate this paper to the late Roland Wollast who did the pioneering work on the silica biogeochemistry in the Scheldt estuary.

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  1. Marie Lionard

    Present address: Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, CP 3300 Rimouski, QC, G5L 3A1, Canada

  2. Koenraad Muylaert

    Present address: K.U. Leuven, Campus Kortrijk, Biology Department, E. Sabbelaan 53, 8500, Kortrijk, Belgium

Authors and Affiliations

  1. Laboratoire d’Océanographie Chimique et Géochimie des Eaux, Faculté des Sciences, Université Libre de Bruxelles, Campus de la Plaine, CP 208, Boulevard du Triomphe, 1050, Brussels, Belgium

    Vincent Carbonnel & Lei Chou

  2. Protistology and Aquatic Ecology, Biology Department, Ghent University, Krijgslaan 281-S8, 9000, Ghent, Belgium

    Marie Lionard & Koenraad Muylaert

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  1. Vincent Carbonnel
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Carbonnel, V., Lionard, M., Muylaert, K. et al. Dynamics of dissolved and biogenic silica in the freshwater reaches of a macrotidal estuary (The Scheldt, Belgium). Biogeochemistry 96, 49–72 (2009). https://doi.org/10.1007/s10533-009-9344-6

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