Preliminary estimate of primary production by phytoplankton in Marennes-Oléron Bay,France

The macrotidal bay of Marennes-Oléron is the most important French site for shellfish production (oysters and mussels); yet the primary productivity of the phytoplankton compartment in this system is not well known. In this study, photosynthetic parameters were determined using ¹⁴C incubations of bottom and surface water samples, during fall, winter and summer (2001–2002), along a north–south transect in the bay. Estimates of primary productivity showed that water column primary production is light-limited in the bay and that a BZ_pI₀ type model can be applied. Spatial differences existed in the bay, with a more productive northern zone and less productive river area. With a water column primary production of 185 g C m⁻² yr⁻¹, Marennes-Oléron Bay lies in the mean range for phytoplankton primary production capacity among European and North American estuaries.