Multiscale harmonised automated observations of phytoplankton biomass, diversity and productivity dynamics in the English Channel and North Sea as part of the coastal Pilot Super Site approach (JERICO S3)
Résumé
Multiscale harmonised automated observation of phytoplankton is essential for accurately monitoring changes in marine coastal ecosystems state and functioning. Novel approaches are currently applied within the English Channel and North Sea coastal Pilot Super Site of the Joint European Research Infrastructure for Coastal Observatories (JERICO-S3) for provision of sustained multidisciplinary observations. This site is characterized by significant connectivity to adjacent seas, strong hydrodynamics and high riverine inputs, influencing biogeochemical and biological processes like high productivity and recurring phytoplankton blooms, some them of potential impact on marine food webs, as well as human health and economy. The intrinsic knowledge on phytoplankton biomass, diversity and productivity dynamics are completed, at different spatial and temporal scales, through the harmonisation of observations (including near-real time in vivo automated approaches implemented for almost a decade). Integrated phytoplankton observations are carried out combining reference methods with innovative automated in vivo imaging inflow/in situ/benchtop devices, automated flow cytometers, as well as multispectral/variable fluorometers, implemented in fixed autonomous stations, moorings, dedicated cruises and ships of opportunity (FerryBox). Functional and taxonomical diversity are addressed in the frame of different monitoring networks carried out in four contrasted ecosystems from the Celtic Seas and English Channel to the German Bight in the North Sea. Moreover, the models used to compute high resolution-resolved photosynthetic parameters and primary production using variable fluorescence measurements give insights into different seasonal patterns, which are respectively synchronous or in delay with that of chlorophyll biomass and community changes. These measurements provide a more precise information on the distribution and dynamics of phytoplankton functional groups (flow cytometry) and main taxa (imaging) at high spatial and temporal resolution assigning community changes to different bloom situations and pelagic habitats state, complementing physical, biogeochemical and biological variables. Finally, harmonisation in data pipelines conform to the FAIR principle and synthesis based on conventional statistics as well as on IA/ML approaches makes it possible to address scientific, societal and economic challenges through a new perspective, facing global and local changes.