The Bay of Seine receives in a naturally confined embayment, the important nitrogen loadings from the Seine river. This induces a high primary production during spring and summer in the river plume, and every year, chlorophyll concentrations reach values between 30 and 70 mg m-3 (Aminot et al., 1997). Diatoms are dominant, but flagellates can become abundant in late summer: Lepidodinium (ex: Gymnodinium) chlorophorum reached 120 million cells l-1 along the Calvados coast in August 2009.
Dinophysis sp. blooms can also reach 106 cells l-1 and induce acute DSP toxicity of shellfishes (Le Grand, 1994).
Aminot, A., Guillaud, J.F., Kérouel, R., 1997. La baie de Seine: hydrologie, nutriments et chlorophylle _1978–1994. Edition IFREMER, Repères Océan, 14, 148 pp.
Le Grand, J., 1994. Bilan du réseau de surveillance phytoplanctonique en Normandie _1989–1992. IFREMER, Rapport Ifremer/DEL/94.09, Port-en Bessin, 72 pp.