| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4548064 | Journal of Marine Systems | 2013 | 13 Pages |
•Characterisation of three areas, based on the hydrological properties of the water mass.•Dynamics of phytoplankton in these areas, importance of DIP spot.•Estimation of productivity dynamics by using PAM from ships of opportunity.•Regulation of photosynthetic parameters by nutrients and light.•Multivariate analyses coupling physical, chemical and biological factors.
The dynamics of physicochemical, phytoplankton communities and photosynthetic parameters were monitored monthly along a transect in the western English Channel from a ship of opportunity. The transect was divided into three areas, based on the hydrological properties of the water mass: the French area (area 1), a station in the centre of the Channel (area 2), and the English area (area 3). In area 1, a bloom occurred in summer/autumn. Due to the gradual changes of physicochemical parameters, area 1 can be described as an ecocline where species adapted to a wide range of physicochemical properties were observed. The area was characterised by the co-dominance of diatoms and dinoflagellates. In area 2, a spot with a high concentration of dissolved inorganic phosphate (DIP) was sampled before and after a bloom of Karenia mikimotoï, suggesting that DIP availability may explain the occurrence of this dinoflagellate species in this area. Area 3 was characterised by two phytoplankton peaks, one in spring and one in late summer/early autumn. Production was controlled by light in area 1, by nutrients in area 2, and by light in spring and by nutrients in summer/autumn in area 3. A link between the chlorophyll a (Chla) biomass and primary production was not systematically observed, suggesting that Chla is not a good proxy for production. On the other hand, a strong link was observed between the relative maximum electron transport rate (rETRmax) and the maximum electron transport rate per chlorophyll unit (Chl_ETRmax). rETRmax consequently appears to be a good indicator of the dynamics of productivity in this area, making it possible to monitor it using PAM (pulse amplitude modulated) from ships of opportunity.
