Scaling of coastal phytoplankton features by optical remote sensors: comparison with a regional ecosystem model

Different scales of hydrological and biological patterns of the Bay of Biscay are assessed using space‐borne and airborne optical remote sensing data, field measurements and a 3‐dimensional biophysical model. If field measurements provide accurate values on the vertical dimension, ocean colour data offer frequent observations of surface biological patterns at various scales of major importance for the validation of ecosystem modelling. Although the hydro‐biological model of the continental margin reproduces the main seasonal variability of surface biomass, the optical remote sensing data have helped to identify low grid resolution, input inaccuracies and neglect of swell‐induced erosion mechanism as model limitations in shallow waters. Airborne remote sensing is used to show that satellite data and field measurements are unsuitable for comparison in the extreme case of phytoplankton blooms in patches of a few hundred metres. Vertically, the satellite observation is consistent with near surface in situ measurements as the sub‐surface chlorophyll maximum usually encountered in summer is not detected by optical remote sensing. A mean error (δC/C) of 50.5% of the chlorophyll‐a estimate in turbid waters using the SeaWiFS‐OC5 algorithm allows the quantitative use of ocean colour data by the coastal oceanographic community.

[1]  J. Dubois,et al.  Technical note Empirical algorithm using SeaWiFS hyperspectral bands: A simple test , 1998 .

[2]  J. Le Fèvre,et al.  Aspects of the Biology of Frontal Systems , 1987 .

[3]  Terry E. Whitledge,et al.  Nutrients, irradiance, and mixing as factors regulating primary production in coastal waters impacted by the Mississippi River plume , 1999 .

[4]  P. Morin,et al.  Évolution printanière des éléments nutritifs et du phytoplancton sur le plateau continental armoricain (Europe du Nord-Ouest) , 1991 .

[5]  K. Schaumann,et al.  Hydrographic and biological characteristics of a Noctiluca scintillans red tide in the German Bight, 1984 , 1988 .

[6]  C. Dupouy,et al.  Remote sensing observations of biological material by LANDSAT along a tidal thermal front and their relevancy to the available field data , 1983 .

[7]  R. Pingree,et al.  Structure, strength and seasonality of the slope currents in the Bay of Biscay region , 1990, Journal of the Marine Biological Association of the United Kingdom.

[8]  J. Fèvre,et al.  Influence of temporal characteristics of physical phenomena on plankton dynamics, as shown by North-West European marine ecosystems , 1988 .

[9]  R. Pingree,et al.  The Structure of the Internal Tide at the Celtic Sea Shelf Break , 1984, Journal of the Marine Biological Association of the United Kingdom.

[10]  R. Smith,et al.  Remote Senslng and Depth Distribution of Ocean Chlorophyll , 1981 .

[11]  K. Hirayama,et al.  Effects of salinity, food level and temperature on the population growth of Noctiluca scintillans (Macartney). , 1992 .

[12]  J. Fèvre,et al.  On the relationships of Noctiluca swarming off the western coast of brittany with hydrological features and plankton characteristics of the environment , 1970 .

[13]  C. Lorenzen,et al.  DETERMINATION OF CHLOROPHYLL AND PHEO‐PIGMENTS: SPECTROPHOTOMETRIC EQUATIONS1 , 1967 .

[14]  Y. Camus,et al.  Formation de gradients thermiques à la surface de l'océan, au-dessus d'un talus, par interaction entre les ondes internes et le mélange dû au vent , 1986 .

[15]  F. Gohin,et al.  A five channel chlorophyll concentration algorithm applied to SeaWiFS data processed by SeaDAS in coastal waters , 2002 .

[16]  J. Froidefond,et al.  SeaWiFS data interpretation in a coastal area in the Bay of Biscay , 2002 .

[17]  Karen S. Baker,et al.  Optical classification of natural waters 1 , 1978 .

[18]  Alain Biseau,et al.  Definition of a directed fishing effort in a mixed-species trawl fishery, and its impact on stock assessments , 1998 .

[19]  C. Koutsikopoulos,et al.  Physical processes and hydrological structures related to the Bay of Biscay anchovy , 1996 .

[20]  Pascal Lazure,et al.  3D modelling of seasonal evolution of Loire and Gironde plumes on Biscay Bay continental shelf , 1998 .

[21]  R. Maze.  Generation and propagation of non-linear internal waves induced by the tide over a continental slope , 1987 .

[22]  A. New,et al.  Evidence for internal tidal mixing near the shelf break in the Bay of Biscay , 1990 .

[23]  R. Pingree,et al.  Three anticyclonic slope water oceanic eDDIES (SWODDIES) in the Southern Bay of Biscay in 1990 , 1992 .

[24]  J. Cloern.  The relative importance of light and nutrient limitation of phytoplankton growth: a simple index of coastal ecosystem sensitivity to nutrient enrichment , 1999, Aquatic Ecology.

[25]  P. Castaing,et al.  Étude théorique de l'action des courants de marée et des houles sur les sédiments du plateau continental du Golfe de Gascogne , 1989 .

[26]  J. L'Yavanc,et al.  Observations de courant en Baie de Seine , 1985 .

[27]  M. Mallin,et al.  Alternation of factors limiting phytoplankton production in the Cape Fear River Estuary , 1999 .

[28]  R. Pingree,et al.  Celtic and Armorican slope and shelf residual currents , 1989 .

[29]  H. Claustre,et al.  Comparison between spectrophotometric, fluorometric and HPLC methods for chlorophyll analysis , 1997 .

[30]  C. Videau.  Primary production and physiological state of phytoplankton at the Ushant tidal front (west coast of Brittany, France , 1987 .

[31]  W. Mccluney,et al.  Estimation of the depth of sunlight penetration in the sea for remote sensing. , 1975, Applied optics.

[32]  S. Tassan.  Local algorithms using SeaWiFS data for the retrieval of phytoplankton, pigments, suspended sediment, and yellow substance in coastal waters. , 1994, Applied optics.

[33]  M. Elbrächter,et al.  Aspects of Noctiluca (Dinophyceae) population dynamics , 1998 .