Seasonal survey of the phytoplankton biomass, composition and production in a littoral NW Mediterranean site, with special emphasis on the picoplanktonic contribution

摘要: Abstract Over a one-year cycle, several shifts occur in the phytoplankton community of Bay Banyuls-sur-Mer, French northwestern Mediterranean shallow bay. In order to determine what drives these shifts, seasonal changes littoral are considered together with environmental parameters. Our methodology combined survey physical structure and nutrient contents water column complete characterization at 3-m 24-m depths. The sampling did provide detailed record successions that waters. Intrusions low salinity clearly had significant impact on structure. Such freshening events both freshened surface introduced substantial amounts nutrient. ratio between nitrogen phosphorus changed occasions proved be reliable clue for Picophytoplankton predominated when N:P was below 10:1 under summer warm oligotrophic situations ( Synechococcus Prochlorococcus ) start enrichment (picoeukaryotes). As increased late winter–early spring period, eukaryotic promoted expense . Successions pico-, nano- microphytoplankton communities appeared mainly driven by differences ability acquire nutrients species-specific growth rates. Further picophytoplankton from samples collected during reached 5:1 suggested existence two cyanobacteria sub-populations. This study shows waters not always well mixed availability Banyuls-sur-Mer depends primarily intrusions.