Seasonal dynamics of air-sea CO₂ fluxes in the inner and outer Loire estuary (NW Europe)

International audienceWe investigated partial pressure of CO2 (pCO2) dynamics in the inner and outer Loire estuary (coastal margin of north-western Europe) over an annual cycle (2009-2010) using a comprehensive dataset of pCO2, dissolved oxygen concentration (DO) and ancillary data collected during four cruises conducted in different seasons. In the inner estuary, pCO2 exhibited very large spatial and inter-seasonal amplitudes (from 294 to 2744 μatm) mainly driven by strong heterotrophic respiration from spring to fall, thermodynamic effects in summer and mixing during winter floods. In the outer estuary, during spring and to a lesser extent during summer, the large extension of the plume resulted in stratification of the water column and autotrophic processes induced pCO2 below atmospheric equilibrium in the plume's surface waters (mean values of -65 μatm compared to the atmosphere). During fall, mixing with inner estuary waters influenced by heterotrophic processes induced pCO2 above atmospheric equilibrium (mean values of +86 μatm) in the very restricted and shallow plume. During winter floods, thermodynamics as well as episodic winter phytoplankton blooms were responsible for pCO2 values below atmospheric equilibrium in the plume (mean values of -42 μatm), whereas the adjacent surface waters were at equilibrium with the atmosphere. Air-sea CO2 fluxes in the inner estuary ranged from 41 ± 4 mmol m-2 d-1 during spring to 140 ± 18 mmol m-2 d-1 during fall, compared to an outer estuary minimum of -9.0 ± 1.0 mmol m-2 d-1 during spring and maximum of 7.7 ± 1.1 mmol m-2 d-1 during fall. Integrated over their respective areas, annual CO2 emissions from the inner estuary of 3.2 109 mol C yr-1 were offset by the annual CO2 sink of -17.9 109 mol C yr-1 from the plume alone. Based on four seasonal cruises, it seems that because of its large size during spring and to a lesser extent during winter, the Loire plume significantly impacted estimates of air-sea CO2 fluxes at a regional scale. Comparison with other major estuarine plumes in diverse continental shelf zones seems to indicate a predominance of CO2 sinks in these systems suggesting that other estuarine plumes might counteract inner estuary CO2 emissions at seasonal to annual level

Cardinal Buoys: An Opportunity for the Study of Air-Sea CO 2 Fluxes in Coastal Ecosystems

International audienceFrom 2015 to 2019 we installed high-frequency (HF) sea surface temperature (SST), salinity, fluorescence, dissolved oxygen (DO) and partial pressure of CO 2 (pCO 2) sensors on a cardinal buoy of opportunity (ASTAN) at a coastal site in the southern Western English Channel (sWEC) highly influenced by tidal cycles. The sensors were calibrated against bimonthly discrete measurements performed at two long-term time series stations near the buoy, thus providing a robust multi-annual HF dataset. The tidal transport of a previously unidentified coastal water mass and an offshore water mass strongly impacted the daily and seasonal variability of pCO 2 and pH. The maximum tidal variability associated to spring tides (>7 m) during phytoplankton blooms represented up to 40% of the pCO 2 annual signal at ASTAN. At the same time, the daily variability of 0.12 pH units associated to this tidal transport was 6 times larger than the annual acidification trend observed in the area. A frequency/time analysis of the HF signal revealed the presence of a day/night cycle in the tidal signal. The diel biological cycle accounted for 9% of the annual pCO 2 amplitude during spring phytoplankton blooms. The duration and intensity of the biologically productive periods, characterized by large inter-annual variability, were the main drivers of pCO 2 dynamics. HF monitoring enabled us to accurately constrain, for the first-time, annual estimates of air-sea CO 2 exchanges in the nearshore tidally-influenced waters of the sWEC, which were a weak source to the atmosphere at 0.51 mol CO 2 m −2 yr −1. This estimate, combined with previous studies, provided a full latitudinal representation of the WEC (from 48 • 75 N to 50 • 25 N) over multiple years for air-sea CO 2 fluxes in contrasted coastal ecosystems. The latitudinal comparison showed a clear gradient from a weak source of CO 2 in the tidal mixing region toward sinks of CO 2 in the stratified region with a seasonal thermal front separating these hydrographical provinces. In view of the fact that several continental shelf regions have been reported to have switched from sources to sinks of CO 2 in the last century, weak CO 2 sources in such tidal mixing areas could potentially become sinks of atmospheric CO 2 in coming decades

Decadal Dynamics of the CO2 System and Associated Ocean Acidification in Coastal Ecosystems of the North East Atlantic Ocean

International audienceWeekly and bi-monthly carbonate system parameters and ancillary data were collected from 2008 to 2020 in three coastal ecosystems of the southern Western English Channel (sWEC) (SOMLIT-pier and SOMLIT-offshore) and Bay of Brest (SOMLIT-Brest) located in the North East Atlantic Ocean. The main drivers of seasonal and interannual partial pressure of CO2 (pCO2) and dissolved inorganic carbon (DIC) variabilities were the net ecosystem production (NEP) and thermodynamics. Differences were observed between stations, with a higher biological influence on pCO2 and DIC in the near-shore ecosystems, driven by both benthic and pelagic communities. The impact of riverine inputs on DIC dynamics was more pronounced at SOMLIT-Brest (7%) than at SOMLIT-pier (3%) and SOMLIT-offshore (<1%). These three ecosystems acted as a weak source of CO2 to the atmosphere of 0.18 ± 0.10, 0.11 ± 0.12, and 0.39 ± 0.08 mol m–2 year–1, respectively. Interannually, air-sea CO2 fluxes (FCO2) variability was low at SOMLIT-offshore and SOMLIT-pier, whereas SOMLIT-Brest occasionally switched to weak annual sinks of atmospheric CO2, driven by enhanced spring NEP compared to annual means. Over the 2008–2018 period, monthly total alkalinity (TA) and DIC anomalies were characterized by significant positive trends (p-values < 0.001), from 0.49 ± 0.20 to 2.21 ± 0.39 μmol kg−1 year−1 for TA, and from 1.93 ± 0.28 to 2.98 ± 0.39 μmol kg–1 year–1 for DIC. These trends were associated with significant increases of calculated seawater pCO2, ranging from +2.95 ± 1.04 to 3.52 ± 0.47 μatm year–1, and strong reductions of calculated pHin situ, with a mean pHin situ decrease of 0.0028 year–1. This ocean acidification (OA) was driven by atmospheric CO2 forcing (57–66%), Sea surface temperature (SST) increase (31–37%), and changes in salinity (2–5%). Additional pHin situ data extended these observed trends to the 2008–2020 period and indicated an acceleration of OA, reflected by a mean pHin situ decrease of 0.0046 year–1 in the sWEC for that period. Further observations over the 1998–2020 period revealed that the climatic indices North Atlantic Oscillation (NAO) and Atlantic Multidecadal Variability (AMV) were linked to trends of SST, with cooling during 1998–2010 and warming during 2010–2020, which might have impacted OA trends at our coastal stations. These results suggested large temporal variability of OA in coastal ecosystems of the sWEC and underlined the necessity to maintain high-resolution and long-term observations of carbonate parameters in coastal ecosystems.Introductio

High-sensitivity C-reactive protein in chronic low back pain with vertebral end-plate Modic signal changes.

International audienceOBJECTIVE: To assess high-sensitivity C-reactive protein (hsCRP) level as a measure of low-grade inflammation in relation to Modic vertebral end-plate marrow signal change on magnetic resonance imaging (MRI) in patients with chronic low back pain. METHODS: All patients hospitalized for chronic low back pain in our institution were prospectively enrolled in this pilot study. Serum hsCRP concentration was measured by immunoturbidimetric assay. MR images were evaluated independently by a panel of 2 spine specialists and a radiologist. Recording of clinical parameters, MRI evaluation, and hsCRP level of each patient was blinded. RESULTS: Three groups of 12 consecutive patients (Modic 0, Modic I, and Modic II signal changes on MRI) were prospectively selected. Serum hsCRP level was significantly different in the 3 groups (P = 0.002) and especially high in the Modic I group (P = 0.002 compared with Modic 0 and II groups): mean +/- SD 1.33 +/- 0.77 mg/liter in the Modic 0 group, 4.64 +/- 3.09 mg/liter in the Modic I group, and 1.75 +/- 1.30 mg/liter in the Modic II group. The only difference in clinical parameters among the 3 groups (P = 0.001) was that the worst painful moment during the previous 24 hours occurred during the late night and morning for all Modic I patients (P = 0.001 compared with Modic 0 and P = 0.002 compared with Modic II). CONCLUSION: Low-grade inflammation indicated by high serum hsCRP level in patients with chronic low back pain could point to Modic I signal changes. This result could help physicians predict the patients with Modic I signals to more precisely prescribe the correct imaging procedure and local antiinflammatory treatment in such patients

Le maceron et la mygale — Une enquête ethnobotanique sur les pratiques d'inventaire naturaliste à Paris

In October 1997, a few seedlings of "maceron" (Smyrnum olusatrum L.), a long-forgotten vegetable, were discovered in an abandoned railway tract in the periphery of Paris. It became the starting point of an ethnological study on the different steps taken by a naturalist conducting an inventory. From the inner beltway of the city to the Jardin des Plantes (Botanical Garden) ; from the Association of Open Spaces to the seed bank at the Museum of Natural History, this account follows the research conducted, and identifies different people, professions and institutions who contribute to the inventory of the wild biological wealth of the city.En octobre 1997, quelques pieds de maceron — un légume depuis longtemps passé de mode (Smyrnium olusatrum L.) — sont découverts sur l'ancienne voie ferrée périphérique de Paris. C'est le point de départ d'une enquête ethnologique sur diverses démarches d'inventaire naturaliste. De la Petite Ceinture au Jardin des Plantes, de l'association ESPACES à la Graineterie du Muséum, le récit suit le déroulement de l'enquête, et met en scène des personnages, des compétences et des institutions sociales qui contribuent à la patrimonialisation des richesses biologiques sauvages dans la ville.Lizet Bernadette, Aymonin Gérard, Ballot Laurent, Bonvarlet Claude, Delfosse Emmanuel, Douineau Alain, Fradin Yann, Jakubyszyn Michel, Jarry Guy, Macé Bruno, Pauthier Yves, Précigout Guy. Le maceron et la mygale — Une enquête ethnobotanique sur les pratiques d'inventaire naturaliste à Paris. In: Journal d'agriculture traditionnelle et de botanique appliquée, 39ᵉ année, bulletin n°2,1997. Sauvages dans la ville. De l'inventaire naturaliste à l'écologie urbaine, sous la direction de Bernadette Lizet, Anne-Elizabeth Wolf et John Celecia. pp. 219-239

French coastal network for carbonate system monitoring: The CocoriCO2 dataset

International audienceSince the beginning of the industrial revolution, atmospheric carbon dioxide (CO2) concentrations have risen steadily and have induced a decrease of the averaged surface ocean pH by 0.1 units, corresponding to an increase in ocean acidity of about 30%. In addition to ocean warming, ocean acidification poses a tremendous challenge to some marine organisms, especially calcifiers. The need for long-term oceanic observations of pH and temperature is a key element to assess the vulnerability of marine communities and ecosystems to these pressures. Nearshore productive environments, where a large majority of shellfish farming activities are conducted, are known to present pH levels as well as amplitudes of daily and seasonal variations that are much larger than those observed in the open ocean. Yet, to date, there are very few coastal observation sites where these parameters are measured simultaneously and at high frequency

French coastal network for carbonate system monitoring: the CocoriCO2 dataset

International audienceSince the beginning of the industrial revolution, atmospheric carbon dioxide (CO2) concentrations have risen steadily and have induced a decrease of the averaged surface ocean pH by 0.1 units, corresponding to an increase in ocean acidity of about 30 %. In addition to ocean warming, ocean acidification poses a tremendous challenge to some marine organisms, especially calcifiers. The need for long-term oceanic observations of pH and temperature is a key element to assess the vulnerability of marine communities and ecosystems to these pressures. Nearshore productive environments, where a large majority of shellfish farming activities are conducted, are known to present pH levels as well as amplitudes of daily and seasonal variations that are much larger than those observed in the open ocean. Yet, to date, there are very few coastal observation sites where these parameters are measured simultaneously and at high frequency. To bridge this gap, an observation network was initiated in 2021 in the framework of the CocoriCO2 project. Six sites were selected along the French Atlantic and Mediterranean coastlines based on their importance in terms of shellfish production and the presence of high- and low-frequency monitoring activities. At each site, autonomous pH sensors were deployed, both inside and outside shellfish production areas, next to high-frequency CTD (conductivity–temperature–depth) probes operated through two operating monitoring networks. pH sensors were set to an acquisition rate of 15 min, and discrete seawater samples were collected biweekly in order to control the quality of pH data (laboratory spectrophotometric measurements) as well as to measure total alkalinity and dissolved inorganic carbon concentrations for full characterization of the carbonate system. While this network has been up and running for more than 2 years, the acquired dataset has already revealed important differences in terms of pH variations between monitored sites related to the influence of diverse processes (freshwater inputs, tides, temperature, biological processes). Data are available at https://doi.org/10.17882/96982 (Petton et al., 2023a)

A catalog of numerical centrosome defects in epithelial ovarian cancers

International audienceCentrosome amplification, the presence of more than two centrosomes in a cell is a common feature of most human cancer celllines. However, little is known about centrosome numbers inhuman cancers and whether amplification or other numericalaberrations are frequently present. To address this question, wehave analyzed a large cohort of primary human epithelial ovariancancers (EOCs) from 100 patients. We found that rigorous quantitation of centrosome number in tumor samples was extremelychallenging due to tumor heterogeneity and extensive tissue disorganization. Interestingly, even if centrosome clusters could beidentified, the incidence of centrosome amplification was not comparable to what has been described in cultured cancer cells. Surprisingly, centrosome loss events where a few or many nuclei werenot associated with centrosomes were clearly noticed and overallmore frequent than centrosome amplification. Our findings highlight the difficulty of characterizing centrosome numbers inhuman tumors, while revealing a novel paradigm of centrosomenumber defects in EOCs

The climatic debt is growing in the understorey of temperate forests: Stand characteristics matter

Aim. Climate warming reshuffles biological assemblages towards less cold-adapted but more warm-adapted species, a process coined thermophilization. However, the velocity at which this process is happening generally lags behind the velocity of climate change, generating a climatic debt the temporal dynamics of which remain misunderstood. Relying on high-resolution time series of vegetation data from a long-term monitoring network of permanent forest plots, we aim at quantifying the temporal dynamics – up to a yearly resolution – of the climatic debt in the understorey of temperate forests before identifying the key determinants that modulate it. Location. France. Time period. 1995–2017. Taxa studied. Vascular plants. Methods. We used the community temperature index (CTI) to produce a time series of understorey plant community thermophilization, which we subsequently compared to a time series of mean annual temperature changes over the same period and for the same sites. The direction and magnitude of the difference (i.e., the climatic debt) was finally analysed using linear mixed-effect models to assess the relative contributions of abiotic and biotic determinants, including forest stand characteristics. Results. We found a significant increase in CTI values over time (0.08–0.09 °C/decade), whereas the velocity of mean annual temperature changes was three times higher over the same period (0.22–0.28 °C/decade). Hence, the climatic debt increased over time and was greater in forest stands with higher basal area or older trees as well as under warmer macroclimate. By contrast, a greater frequency of anthropogenic disturbances decreased the climatic debt, while natural disturbances and herbivory had no impact. Conclusions. Although often overlooked in understanding the climatic debt of forest biodiversity, changes in forest stand characteristics may modulate the climatic debt by locally modifying microclimatic conditions. Notably, the buffering effect of the upper canopy layer implies microclimate dynamics that may provide more time for understorey plant communities to locally adapt

The climatic debt is growing in the understorey of temperate forests: Stand characteristics matter

International audienceAim. Climate warming reshuffles biological assemblages towards less cold-adapted but more warm-adapted species, a process coined thermophilization. However, the velocity at which this process is happening generally lags behind the velocity of climate change, generating a climatic debt the temporal dynamics of which remain misunderstood. Relying on high-resolution time series of vegetation data from a long-term monitoring network of permanent forest plots, we aim at quantifying the temporal dynamics – up to a yearly resolution – of the climatic debt in the understorey of temperate forests before identifying the key determinants that modulate it. Location. France. Time period. 1995–2017. Taxa studied. Vascular plants. Methods. We used the community temperature index (CTI) to produce a time series of understorey plant community thermophilization, which we subsequently compared to a time series of mean annual temperature changes over the same period and for the same sites. The direction and magnitude of the difference (i.e., the climatic debt) was finally analysed using linear mixed-effect models to assess the relative contributions of abiotic and biotic determinants, including forest stand characteristics. Results. We found a significant increase in CTI values over time (0.08–0.09 °C/decade), whereas the velocity of mean annual temperature changes was three times higher over the same period (0.22–0.28 °C/decade). Hence, the climatic debt increased over time and was greater in forest stands with higher basal area or older trees as well as under warmer macroclimate. By contrast, a greater frequency of anthropogenic disturbances decreased the climatic debt, while natural disturbances and herbivory had no impact. Conclusions. Although often overlooked in understanding the climatic debt of forest biodiversity, changes in forest stand characteristics may modulate the climatic debt by locally modifying microclimatic conditions. Notably, the buffering effect of the upper canopy layer implies microclimate dynamics that may provide more time for understorey plant communities to locally adapt