Basin-scale spatio-temporal variability and control of phytoplankton photosynthesis in the Baltic Sea: The first multiwavelength fast repetition rate fluorescence study operated on a ship-of-opportunity

This study presents the results of the first field application of a flow-through multi-wavelength Fast Repetition Rate fluorometer (FRRF) equipped with two excitation channels (458 and 593 nm). This device aims to improve the measurement of mixed cyanobacteria and algae community's photosynthetic parameters and was designed to be easily incorporated into existing ferrybox systems. We present a spatiotemporal analysis of the maximum photochemical efficiency (Fv/Fm) and functional absorption cross section (σPSII) recorded from April to August 2014 on a ship-of-opportunity commuting twice per week between Helsinki (Finland) and Travemünde (Germany). Temporal variations of Fv/Fm and σPSII differed between areas of the Baltic Sea. However, even though the Baltic Sea is characterized by several physico-chemical gradients, no gradient was observed in Fv/Fm and σPSII spatial distribution suggesting complex interactions between biotic and abiotic controls. σPSII was sensitive to phytoplankton seasonal succession and thus differed according to the wavelength used to excite photosystems II (PSII) pigments. This was particularly true in summer when high σPSII(593) values were observed later and longer than high σPSII(458) values, reflecting the role of cyanobacteria in photosynthetic light uptake measured at community scale. In contrast, Fv/Fm variations were similar after excitation at 458 nm or 593 nm suggesting that the adjustment of Fv/Fm in response to environmental factors was similar for the different groups (algae vs. cyanobacteria) present within the phytoplankton community

A New Model of the Crustal Magnetic Field of Mars Using MGS and MAVEN

International audienc

Monitoring of phytoplankton and Harmful Algal Blooms in coastal waters by combining innovative semi-automated tools (scanning flow cytometry & spectral fluorometry)

National audienceIn order to address phytoplankton dynamics in aquatic systems and to detect short term changes in phytoplankton composition, there is a need for innovative and reproducible monitoring procedures that could be applied at high frequency. Indeed, current methodologies and monitoring practices are not equipped to deal with fast changes in phytoplankton composition, which can reflect changes in the environmental status of aquatic systems and/or the occurrence of harmful events (Harmful Algal Blooms-HAB). Amongst recent research,the DYMAPHY project (Development of a DYnamic observation system for the assessment of MArine water quality, based on PHYtoplankton analysis, 2010-2014, www.dymaphy.eu), co-funded by the European Regional Development Funds (ERDF), aimed at contributing to a better assessment of the quality of marine waters in the Eastern English Channel and Southern North Sea (INTERREG IV A “2 Seas”) through the study of phytoplankton and related environmental parameters, at high spatial and temporal resolution. By combining innovativetechniques as pulse-shape recording scanning flow cytometry (CytoSense, Cytobuoy©) and spectral fluorescence (Fluoroprobe and AOA bbe©), compared to reference techniques, the DYMAPHY project proposed within a cross-border (France, England and Netherlands) effective work, better-standardized procedures and greater automation in data analysis for monitoring phytoplankton. This approach was tested in common inter comparison/calibration exercises, as well as in common international cruises in different coastal ecosystems of the “2 Seas” area. A discussion is carried out on the limits of integration of these methodologies inroutine monitoring systems

Monitoring of phytoplankton and Harmful Algal Blooms in coastal waters by combining innovative semi-automated tools (scanning flow cytometry & spectral fluorometry)

National audienceIn order to address phytoplankton dynamics in aquatic systems and to detect short term changes in phytoplankton composition, there is a need for innovative and reproducible monitoring procedures that could be applied at high frequency. Indeed, current methodologies and monitoring practices are not equipped to deal with fast changes in phytoplankton composition, which can reflect changes in the environmental status of aquatic systems and/or the occurrence of harmful events (Harmful Algal Blooms-HAB). Amongst recent research,the DYMAPHY project (Development of a DYnamic observation system for the assessment of MArine water quality, based on PHYtoplankton analysis, 2010-2014, www.dymaphy.eu), co-funded by the European Regional Development Funds (ERDF), aimed at contributing to a better assessment of the quality of marine waters in the Eastern English Channel and Southern North Sea (INTERREG IV A “2 Seas”) through the study of phytoplankton and related environmental parameters, at high spatial and temporal resolution. By combining innovativetechniques as pulse-shape recording scanning flow cytometry (CytoSense, Cytobuoy©) and spectral fluorescence (Fluoroprobe and AOA bbe©), compared to reference techniques, the DYMAPHY project proposed within a cross-border (France, England and Netherlands) effective work, better-standardized procedures and greater automation in data analysis for monitoring phytoplankton. This approach was tested in common inter comparison/calibration exercises, as well as in common international cruises in different coastal ecosystems of the “2 Seas” area. A discussion is carried out on the limits of integration of these methodologies inroutine monitoring systems