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)

International audienceMultiscale 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

EcoNum, a research unit devoted to marine environment monitoring

The monitoring of coastal environments remains a research domain of great interest and concern. Coastal ecosystems are threatened by natural and human-induced stressors and are, as transitional environments, particularly sensitive to disturbances. EcoNum first research thematic revolves around hermatypic corals, calcifying organisms, and their adaptation potentials to environmental changes including by using original and patented chemostats. The studied organisms are grown and maintained in artificial mesocosms that simulate environmental conditions of a natural system. This infrastructure allows to perform long-term experiments, giving time to organisms to adapt to the tested conditions (e.g., increased temperature or lowered pH). Longer-term studies have demonstrated that many organisms are more resistant to environmental stressors than previously observed on the short-term. EcoNum also studies coastal plankton abundance and diversity. Plankton is particularly sensitive to physicochemical changes of water bodies. The classification and the enumeration of planktonic organisms require specialized tools in order to analyse time series of multiple samples. EcoNum has developed a software for the semi-automatic classification of planktonic organisms called Zoo/PhytoImage. This software has been used to study a 10-year time series of coastal Mediterranean zooplankton samples. The concomitant analysis of environmental parameters registered at high frequency with specific statistical tools such as the R package pastecs allows to understand the processes governing the changes observed in plankton assemblages. The use and the development of statistical tools in R (e.g., Zoo/Phytoimage, pastecs) is a priority of EcoNum to favour open access knowledge and reproductive sciences. EcoNum research topics also focus on coastal ecotoxicology. Chemicals, including trace elements, remain contaminants of concern, mainly in coastal environments that are the final sink of inland pollution sources. The chemical integrity of coastal ecosystems thus has to be accurately monitored. The partitioning of chemicals between their dissolved, particulate and sedimentary phases does not provide information on their bioavailability. EcoNum thus monitors coastal waters using bioindicator species such as seagrasses, mussels or sand worms. A global map of the contamination of the Mediterranean by trace elements has been drawn using seagrasses has bioindicator species. EcoNum also studies trace element ecology and toxicology. For instance, it has demonstrated the toxicity of copper on the coral Seriatopora hystrix and it's symbiont's photosynthetic processes, or its bioaccumulation and basipetal translocation towards rhizomes in the seagrass Posidonia oceanica as reserve nutrient for subsequent leaf growth. Finally, coastal vegetated systems are potential carbon thinks (or sources) in the global carbon cycle. Therefore, EcoNum studies the primary productivity of seagrass meadows, from the individual to the community, with measuring techniques as diverse as PAM-fluorometry or biomass production determination. To conclude, EcoNum is a research unit devoted to marine environment monitoring. It develops research thematics on major coastal communities such as coral reefs, seagrass beds or plankton assemblages and studies their natural dynamics and the effects of stressors on their global functioning

Automated optical approaches for in vivo multiscale monitoring of phytoplankton communities and HABs in the English Channel and North Sea

International audienceAutomated optical observations of phytoplankton communities are currently implemented in eastern English Channel and southern North Sea on different platforms (fixed autonomous stations, moorings, dedicated cruises and measurements/ships of opportunity) as a complement of long term monitoring networks in the. These marginal seas are characterized by significant connectivity to adjacent ocean and seas, strong hydrodynamics and low to high riverine inputs, influencing biogeochemical and biological processes like high productivity and recurring phytoplankton blooms, including some Harmful Algal Blooms-HABs of potential impact on marine food webs, as well as on human health and economy. Integrated phytoplankton observations are carried out combining reference methods with innovative automated in vivo imaging inflow/in situ/benchtop devices, pulse shape-recording flow cytometers, as well as in vivo multispectral fluorometers. These measurements provide 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. The in vivo approaches allow tracking HABs at different spatial and temporal scales, through the harmonisation of observations (including near-real time in vivo automated approaches implemented for almost a decade), at almost real time, and become a helpful tool for managers of these events. 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