Pascal Conan | Sorbonne University (original) (raw)

Papers by Pascal Conan

We also printed these comments on a pdf file and added it in supplement (Revewer2.pdf) SPECIFIC C... more We also printed these comments on a pdf file and added it in supplement (Revewer2.pdf) SPECIFIC COMMENTS Abstract:-The abstract states that the study will help to "understand how the severe drought period influenced biogeochemical cycling and phytoand bacterio-plankton communities", nevertheless the study does not compare the data obtained during this period to any other records (maybe due to the fact that they do not exist) obtained during in more "classic" situation. This statement needs to be nuanced.

The PHYTOBS dataset includes long-term time series on marine microphytoplankton, since 1987, alon... more The PHYTOBS dataset includes long-term time series on marine microphytoplankton, since 1987, along the whole French metropolitan coast. Microphytoplankton data cover microscopic taxonomic identifications and counts. The whole dataset is available, it includes 25 sampling locations. PHYTOBS network studies microphytoplankton diversity in the hydrological context along French coasts under gradients of anthropogenic pressures. PHYTOBS network allows to analyse the responses of phytoplankton communities to environmental changes, to assess the quality of the coastal environment through indicators, to define ecological niches, to detect variations in bloom phenology, and to support any scientific question by providing data. The PHYTOBS network provides the scientific community and stakeholders with validated and qualified data, in order to improve knowledge regarding biomass, abundance and composition of marine microphytoplankton in coastal and lagoon waters in their hydrological context....

The present work is based on a dataset comprised of 31 Biogeochemical (BGC) Argo floats that coll... more The present work is based on a dataset comprised of 31 Biogeochemical (BGC) Argo floats that collected 0-1000 m vertical profiles of biogeochemical and optical data from 2012 to 2016 in the Mediterranean Sea. The dataset was integrated in 1-dimensional model simulations following the trajectories of each float and considering measured photosynthetically available radiation (PAR) profiles as the reference light parameterization. The simulations were aimed to be consistent with data measured by float sensors, especially in terms of the deep chlorophyll maximum (DCM) depth. Moreover, we tested several light models in order to estimate their impact on modeled biogeochemical properties, including self-shading dynamics based on chlorophyll and colored dissolved organic matter (CDOM) concentrations. The results, evaluated with the corresponding in-situ BGC-Argo chlorophyll data, indicate that the proposed approach allows to properly simulate the chlorophyll dynamics and illustrate how PAR and vertical mixing are essential environmental regulation factors driving primary producers dynamics. The higher skills are reached using in-situ PAR, but some of the alternative bio-optical models here presented show comparable skill in reproducing DCM depth spatial variability. Simulation results show that during the stratification phase the diel cycle has significant impact on the surface chlorophyll regimes. The approach here presented serves as a computationally smooth solution to analyse BGC-Argo floats data and to corroborate hypotheses on their spatio-temporal variability.

LOV NAME WMO CODE 1 lovbio001i 2 lovbio015c 3 lovbio016c 4 lovbio016d 5 lovbio017b 6 lovbio018c 7... more LOV NAME WMO CODE 1 lovbio001i 2 lovbio015c 3 lovbio016c 4 lovbio016d 5 lovbio017b 6 lovbio018c 7 lovbio035b 8 lovbio039b 9 lovbio042c 10 lovbio053b 11 lovbio058c 12 lovbio063c 13 lovbio064b 14 lovbio064c 15 lovbio066c 16 lovbio066d 17 lovbio067c 18 lovbio068d 19 lovbio072c 20 lovbio083d 21 lovbio085d 22 lovbio088d 23 lovbio089d 24 lovbio090d 25 lovbio091d 26 lovbio093d 27 ogsbio001b 28 ogsbio002b 29 ogsbio003b 30 ogsbio004b 31 ogsbio006b

HAL (Le Centre pour la Communication Scientifique Directe), 2006

Frontiers in Marine Science, Jun 25, 2019

To understand and predict the physical, chemical, and biological processes at play in coastal and... more To understand and predict the physical, chemical, and biological processes at play in coastal and nearshore marine areas requires an integrated, interdisciplinary approach. The case study of the French structuration of coastal ocean and nearshore observing systems provides an original overview on a federative research infrastructure named ILICO. It is a notable example of national structuration and pan-institution efforts to investigate the forefront of knowledge on the processes at work within the critical coastal zone. ILICO comprises, in a pluridisciplinary approach, eight distributed networksystems of observation and data analysis that are accredited and financially supported by French research institutions and the French Ministry for Higher Education, Research, and Innovation. ILICO observation points are implemented along metropolitan and overseas French coasts, where coastline dynamics, sea level evolution, physical and biogeochemical water properties, coastal water dynamics, phytoplankton composition, and health of coral reefs are monitored in order to address a wide range of scientific questions. To give an overview of the diversity and potential of the observations carried out, this paper offers a detailed presentation of three constituting networks: Service Observation en Milieu LITtoral (SOMLIT), with homogeneous sampling strategies, DYNALIT, with heterogeneous sampling strategies adapted to different environments, and Mediterranean Ocean Observing System for the Environment (MOOSE), an integrated, pluri-disciplinary coastal/offshore regional observatory in the northwestern Mediterranean Sea. ILICO was conceived using a European framework. It addresses the great challenges of the next decade in terms of sustainability, cost-efficiency, interoperability, and innovation. This paper emphasizes the added-value of federating these systems, and highlights some recommendations for the future.

Journal Of Geophysical Research: Oceans, Dec 1, 2017

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Frontiers in Marine Science

IntroductionWhile crucial to ensuring the production of accurate and high-quality data—and to avo... more IntroductionWhile crucial to ensuring the production of accurate and high-quality data—and to avoid erroneous conclusions—data quality control (QC) in environmental monitoring datasets is still poorly documented.MethodsWith a focus on annual inter-laboratory comparison (ILC) exercises performed in the context of the French coastal monitoring SOMLIT network, we share here a pragmatic approach to QC, which allows the calculation of systematic and random errors, measurement uncertainty, and individual performance. After an overview of the different QC actions applied to fulfill requirements for quality and competence, we report equipment, accommodation, design of the ILC exercises, and statistical methodology specially adapted to small environmental networks (<20 laboratories) and multivariate datasets. Finally, the expanded uncertainty of measurement for 20 environmental variables routinely measured by SOMLIT from discrete sampling—including Essential Ocean Variables—is provided.Re...

HAL (Le Centre pour la Communication Scientifique Directe), 2007

Science of The Total Environment

HAL (Le Centre pour la Communication Scientifique Directe), May 3, 2021

Journal of Geophysical Research: Oceans, 2017

Knowledge of the relative contributions of phytoplankton size classes to zooplankton biomass is n... more Knowledge of the relative contributions of phytoplankton size classes to zooplankton biomass is necessary to understand food‐web functioning and response to climate change. During the Deep Water formation Experiment (DEWEX), conducted in the north‐west Mediterranean Sea in winter (February) and spring (April) of 2013, we investigated phytoplankton‐zooplankton trophic links in contrasting oligotrophic and eutrophic conditions. Size fractionated particulate matter (pico‐POM, nano‐POM, and micro‐POM) and zooplankton (64 to >4000 μm) composition and carbon and nitrogen stable isotope ratios were measured inside and outside the nutrient‐rich deep convection zone in the central Liguro‐Provencal basin. In winter, phytoplankton biomass was low (0.28 mg m−3) and evenly spread among picophytoplankton, nanophytoplankton, and microphytoplankton. Using an isotope mixing model, we estimated average contributions to zooplankton biomass by pico‐POM, nano‐POM, and micro‐POM of 28, 59, and 15%, re...

Marine Ecology Progress Series, 2003

A mesoscale study was conducted in January and February 1999 in the Crozet Basin frontal zones (4... more A mesoscale study was conducted in January and February 1999 in the Crozet Basin frontal zones (43°50' to 45°20' S, 61°00' to 64°30' E) within the southernmost and easternmost convergence area of the Antarctic Circumpolar Current (ACC) and the Agulhas Return Current (ARC). Distribution of biogeochemical parameters was strongly linked to the merged Subtropical (STF) and Subantarctic (SAF) Fronts which mark the border between the cold and less saline subantarctic waters and the warm and more saline subtropical waters. This survey took place during a post-bloom period. Chlorophyll a concentrations were low throughout the study area ranging from 0.2 µg l-1 in the Polar Frontal Zone (PFZ) to 0.4 µg l-1 in the Subtropical Zone (STZ). Maximum chlorophyll a values (0.8 µg l-1) associated with an increase in biogenic silica concentration (from 0.03 to 0.34 µM) and a diatom peak (1.2 × 10 5 cells l-1) were encountered in the northeastern part of the STF edge. Despite northwardly decreasing concentrations of nitrates from 14 µM in the PFZ to 6 µM in the STZ, they were not the main factor limiting phytoplankton growth. Low silicic acid (mean = 0.6 µM) could have limited diatom development in the PFZ and the STZ where diatom numbers were low. In STZ waters, where average diatom numbers were highest, various species of Nitzschia and Thalassiothrix were common, but Pseudonitzschia spp. were dominant. Throughout the survey area, pico-and nano-sized cells dominated the phytoplankton assemblage, and their number was the highest in the STZ. Cyanobacteria, only present in subtropical waters >12.5°C, were the major component of the picoplankton size-fraction. While dinoflagellate numbers were low in the Subantarctic Zone (SAZ), their abundance and species numbers increased in the STZ, where Oxytoxum laticeps became dominant and several further large-size species of Prorocentrum, Ceratium and Gymnodinium appeared in addition to those at the STF. The distribution of different biogeochemical parameters suggests that the Crozet Basin frontal region is a non-exporting system at the end of summer. During this postbloom period, biological activity is low and phytoplankton growth severely limited. This is evidenced by the weak dependence of the partial pressure of carbon dioxide (pCO 2) on biological activity and the importance of the air-sea exchange in maintaining pCO 2 close to saturation.

HAL (Le Centre pour la Communication Scientifique Directe), Dec 16, 2008

Continental Shelf Research, Dec 1, 2005

Frontiers in Marine Science, May 17, 2021

The seasonal variability of the carbonate system in the eastern Mediterranean Sea (EMed) was inve... more The seasonal variability of the carbonate system in the eastern Mediterranean Sea (EMed) was investigated based on discrete total alkalinity (A T), total dissolved inorganic carbon (C T), and pH measurements collected during three cruises around Crete between June 2018 and March 2019. This study presents a detailed description of this new carbonate chemistry dataset in the eastern Mediterranean Sea. We show that the North Western Levantine Basin (NWLB) is unique in terms of range of A T variation vs. C T variation in the upper water column over an annual cycle. The reasons for this singularity of the NWLB can be explained by the interplay between strong evaporation and the concomitant consumption of C T by autotrophic processes. The high range of A T variations, combined to temperature changes, has a strong impact on the variability of the seawater pCO 2 (pCO 2 SW). Based on Argo float data, an entire annual cycle for pCO 2 SW in the NWLB has been reconstructed in order to estimate the temporal sequence of the potential "source" and "sink" of atmospheric CO 2. By combining this dataset with previous observations in the NWLB, this study shows a significant ocean acidification and a decrease in the oceanic surface pH T 25 of −0.0024 ± 0.0004 pH T 25 units.a −1. The changes in the carbonate system are driven by the increase of atmospheric CO 2 but also by unexplained temporal changes in the surface A T content. If we consider that the EMed will, in the future, encounter longer, more intense and warmer summer seasons, this study proposes some perspectives on the carbonate system functioning of the "future" EMed.