MEPS 385:15-32 (2009)  -  DOI: https://doi.org/10.3354/meps07884

Benthic–pelagic coupling and the seasonal silica cycle in the Bay of Brest (France): new insights from a coupled physical–biological model

G. G. Laruelle1,*, P. Regnier1,2, O. Ragueneau3, M. Kempa3, B. Moriceau3, S. Ni Longphuirt3, A. Leynaert3, G. Thouzeau3, L. Chauvaud3

1Faculty of Geosciences, Department of Earth Sciences – Geochemistry, Utrecht University, PO Box 80021, 3508 TA Utrecht, The Netherlands
2Department of Earth and Environmental Sciences, Université Libre de Bruxelles, Brussels, Belgium
3UMR CNRS 6539, Institut Universitaire Européen de la Mer, Place Copernic,Technopôle Brest-Iroise, 29280 Plouzané, France

ABSTRACT: A fully transient, 2-dimensional physical and biological model has been developed to quantify the seasonal cycle of silica in the estuaries–coastal zone continuum of the Bay of Brest (France). The numerical model includes an explicit representation of the benthic–pelagic coupling, which is stimulated by the increasing density of an invasive megabenthic filter feeder, the slipper limpet Crepidula fornicata. The selected spatial resolution allows resolution of the heterogeneous density distribution of these organisms in the bay. Results show that the benthic nutrient dynamics are highly variable and strongly depend on the local conditions. This heterogeneity is not reflected in the pelagic phytoplankton population dynamics because transport and mixing homogenize the distribution of nutrients and biomass. A seasonally resolved silica budget over the entire bay and estuaries emphasizes the important contribution of the benthic recycling fluxes to the supply of dissolved silica (dSi) during the productive period (~50% from 1 April to 1 September). In a prognostic scenario which forecasts the impact of removing the invasive benthic filter feeders, the dSi efflux is reduced by 63% and a pronounced harmful algal bloom of dinoflagellates develops in late summer.


KEY WORDS: Crepidula fornicata · Dissolved silica · Harmful algal bloom · Benthic–pelagic coupling · Nutrient cycles


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Cite this article as: Laruelle GG, Regnier P, Ragueneau O, Kempa M and others (2009) Benthic–pelagic coupling and the seasonal silica cycle in the Bay of Brest (France): new insights from a coupled physical–biological model. Mar Ecol Prog Ser 385:15-32. https://doi.org/10.3354/meps07884

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