Résumé

Several decades of research have led to the acceptance of hydroacoustics as a reliable measurement method to monitor fish population in lakes, but full standardisation and intercalibration are still lacking. The aim of this study was to investigate the effect of sound frequency on acoustic parameters, such as volume backscattering strength, target strength, and the estimation of fish abundance. Data were recorded in situ using 3 frequencies (70, 120, 200 kHz) simultaneously in 2 different lakes. The results among the frequencies were compared and statistically tested. Data from the 70 and 120 kHz frequencies yielded similar results, but the 200 kHz echosounder estimates in temperate lakes seemed different, especially in cases of high fish abundance, which is typical of eutrophic ecosystems. This work indicates that the abundance estimates of fish populations in temperate lakes based on 200 kHz frequency may differ from results obtained using lower frequencies, and that further study is needed.

Auteurs, date et publication :

Auteurs Jean Guillard , Anne Lebourges-Daussy , Helge Balk , Michel Colon , Adam Jóźwik , Małgorzata Godlewska

Publication : Inland Waters

Date : 2014

Volume : 4

Issue : 4

Pages : 435-444

Catégorie(s)

#INRAE #OLA

Auteurs, date et publication :

Auteurs Yannick Bayona , Marc Roucaute , Caroline Gorzerino , Ana Roucaute , Kevin Cailleaud , Anne Bassères , Laurent Lagadic , Thierry Caquet

Date : 2012

Catégorie(s)

#INRAE #PEARL

Résumé

Disease-suppressive soils are soils in which specific soil-borne plant pathogens cause only limited disease although the pathogen and susceptible host plants are both present. Suppressiveness is in most cases of microbial origin. We conducted a comparative metabarcoding analysis of the taxonomic diversity of fungal and bacterial communities from suppressive or non-suppressive (conducive) soils as regards Fusarium wilts sampled from the Châteaurenard region (France). Bioassays confirmed that disease incidence was significantly lower in the suppressive soil than in the conducive soil. Furthermore, we succeeded in partly transferring Fusarium wilt-suppressiveness to the conducive soil by mixing 10% (w/w) of the suppressive soil into the conducive soil. Fungal diversity differed significantly between the suppressive and conducive soils. Among dominant fungal operational taxonomic units (OTUs) affiliated to known genera, seventeen OTUs were detected exclusively in the suppressive soil. These OTUs were assigned to the Acremonium, Chaetomium, Cladosporium, Clonostachys, Fusarium, Ceratobasidium, Mortierella, Penicillium, Scytalidium, and Verticillium genera. Additionally, the relative abundance of specific members of the bacterial community was significantly higher in the suppressive and mixed soils than in the conducive soil. OTUs found more abundant in Fusarium wilt-suppressive soils were affiliated to the bacterial genera Adhaeribacter, Massilia, Microvirga, Rhizobium, Rhizobacter, Arthrobacter, Amycolatopsis, Rubrobacter, Paenibacillus, Stenotrophomonas, and Geobacter. Several of the fungal and bacterial genera detected exclusively or more abundantly in the Fusarium wilt-suppressive soil included genera known for their activity against F. oxysporum. Overall, this study supports the potential role of known fungal and bacterial genera in Fusarium wilt suppressive soils from Châteaurenard and pinpoints new bacterial and fungal genera for their putative role in Fusarium wilt suppressiveness.

Auteurs, date et publication :

Auteurs Katarzyna Siegel-Hertz , Véronique Edel-Hermann , Emilie Chapelle , Sébastien Terrat , Jos M. Raaijmakers , Christian Steinberg

Publication : Frontiers in Microbiology

Date : 2025

Volume : 9

Catégorie(s)

#Genosol #INRAE

Résumé

Many temperate grasslands are used for dairying, and ongoing research aims to better understand these systems in order to increase animal production and soil organic carbon (SOC) stocks. However, it is difficult to fully understand management effects on SOC because most changes are slow and difficult to distinguish from natural variability, even if changes are important over years to decades. Eddy covariance (EC) measurements can overcome this problem by continuously measuring net carbon exchange from pastures, but net balances are very sensitive to even small systematic measurement errors. Combining EC measurements with detailed process-based modelling can reduce the risks inherent in total reliance on EC measurements. Modelling can also reveal information about the underlying processes that drive observed fluxes. Here, we describe carbon exchange patterns of five paddocks situated at four different locations in New Zealand and France where EC data and detailed physiological modelling were available. The work showed that respiration by grazing animals was often only incompletely captured in EC measurements. This was most problematic when fluxes were based on gap-filling, which could have estimated incorrect fluxes during grazing periods based on observations from periods without grazing. We then aimed to extract plant physiological insights from these studies. We found appreciable carbon uptake rates even at temperatures below 0 °C. After grazing, carbon uptake was reduced for up to 2 weeks. This reduction was larger than expected from reduced leaf area after grazing, but the factors contributing to that difference have not yet been identified. Detailed physiological models can also extrapolate findings to new management regimes, environmental conditions or plant attributes. This overcomes the limitation of experimental studies, which are necessarily restricted to actual site and weather conditions allowing models to make further progress on predicting management effects on SOC.

Auteurs, date et publication :

Auteurs Miko U. F. Kirschbaum , Nicolas J. B. Puche , Donna L. Giltrap , Lìyǐn L. Liáng , Abad Chabbi

Publication : Science of The Total Environment

Date : 2020

Volume : 745

Pages : 140917

Catégorie(s)

#ACBB #ACBB Lusignan #ANR-Citation #INRAE

Résumé

In France, a single science-based model has dominated winter wheat N fertilizer management for 40 years. Despite scientific progress, it remains challenging to minimize N losses whilst maximizing grain yield and achieving satisfactory grain protein content. A mismatch between the science-based method and its implementation has been demonstrated. We thought that involving users early in the design process would lead to explore more relevant methods regarding the diversity of N issues and implementation conditions. We used a three-step design process: (1) a diagnosis of the uses of existing methods and tools, (2) a design process combining participatory workshops, generation of new knowledge and model-based prototyping, and (3) a test of the prototype in the users’ conditions. We identified the fixing of a target yield a priori as one of the major problems with the current N fertilization method. We thus established an exploratory conceptual axis: “a fertilization method without target yield”. Design workshops led to a new method based on (1) the regular monitoring of crop N nutrition, (2) the acceptance of periods of crop N deficiency, and (3) the simulation of short-term soil N availability with a crop model. New knowledge was generated, and the Azodyn model was used to build decision rules for N applications, based on viability theory. The prototype was tested by two groups of farmers. We show that, by combining the three steps used here, it was possible to develop an innovative fertilizer method radically different from the dominant paradigm, and positively received by users.

Auteurs, date et publication :

Auteurs Clémence Ravier , Marie-Hélène Jeuffroy , Philippe Gate , Jean-Pierre Cohan , Jean-Marc Meynard

Publication : Nutrient Cycling in Agroecosystems

Date : 2018

Volume : 110

Issue : 1

Pages : 117-134

Catégorie(s)

#INRAE #Record

Auteurs, date et publication :

Auteurs Gaétan Pottier

Date : 2025

Catégorie(s)

#INRAE #PEARL

Résumé

Colloidal particles can act as vectors of adsorbed pollutants in the subsurface, or be themselves pollutants. They can reach the aquifer and impair groundwater quality. The mechanisms of colloid transport and deposition are often studied in columns filled with saturated porous media. Time-lapse profiles of colloid concentration inside the columns have occasionally been derived from magnetic resonance imaging (MRI) data recorded in transport experiments. These profiles are valuable, in addition to particle breakthrough curves (BTCs), for testing and improving colloid transport models. We show that concentrations could not be simply computed from MRI data when both deposited and suspended colloids contributed to the signal. We propose a generic method whereby these data can still be used to quantitatively appraise colloid transport models. It uses the modeled suspended and deposited particle concentrations to compute modeled MRI data that are compared to the experimental data. We tested this method by performing transport experiments with sorbing colloids in sand, and assessed for the first time the capacity of the model calibrated from BTCs to reproduce the MRI data. Interestingly, the dispersion coefficient and deposition rate calibrated from the BTC were respectively overestimated and underestimated compared with those calibrated from the MRI data, suggesting that these quantities, when determined from BTCs, need to be interpreted with care. In a broader perspective, we consider that combining MRI and modeling offers great potential for the quantitative analysis of complex MRI data recorded during transport experiments in complex environmentally relevant porous media, and can help improve our understanding of the fate of colloids and solutes, first in these media, and later in soils.

Auteurs, date et publication :

Auteurs Alizée P Lehoux

Publication : Water Research

Date : 2025

Pages : 9

Catégorie(s)

#INRAE #VirtualSoil

Auteurs, date et publication :

Auteurs M. Muller , J. Jimenez , M. Antonini , Y. Dudal , E. Latrille , F. Vedrenne , J. P. Steyer , D. Patureau

Publication : Waste Management

Date : 2025

Volume : 34

Issue : 12

Pages : 2572-80

Catégorie(s)

#INRAE #PRO

Résumé

Transport of coarse particulate organic matter (CPOM) derived from forest litterfall has been hardly studied in rivers, unlike fine particulate organic matter (FPOM) or dissolved organic matter (DOM). Yet, many rivers are dammed or run into lakes, and there is growing evidence that CPOM accumulation in river delta participates substantially in ecological processes such as greenhouse gas emissions of lakes and reservoirs. We investigated the transport of CPOM and FPOM by the Leysse River (discharge from 0.2 to 106 m3 s−1) to Lake Bourget (France) in relation to aerial litter deposition, river network length, and discharge. Over a 19-month study period, the volume-weighted mean CPOM and FPOM concentrations were 1.3 and 7.7 g m−3, respectively. Most CPOM and FPOM transport occurred during major flood events, and there were power relationships between maximum discharge and particulate organic matter (POM) transport during these events. The annual export of CPOM (190 t AFDM) was 85% of the litter accumulation in autumn on permanent sections of the riverbed (224 t AFDM), which suggests that export is a major process compared to breakdown. Export of CPOM was 1.25 t yr−1 km−2 of the forested catchment area. This study highlights the need to account for long-range CPOM transport to describe the fate of litter inputs to streams and to quantify the organic matter input and processing in lakes and reservoirs.

Auteurs, date et publication :

Auteurs Jérémie Gaillard , Vincent Chanudet , Guillaume Cunillera , Etienne Dambrine

Publication : Water

Date : 2021

Volume : 13

Issue : 19

Pages : 2783

Catégorie(s)

#INRAE #OLA

Auteurs, date et publication :

Auteurs Cecília Lira Melo de Oliveira Santos , Rubens Augusto Camargo Lamparelli , Dantas Araújo Figueiredo , Gleyce Kelly , Stéphane Dupuy , Julie Boury , Ana Cláudia dos Santos Luciano , Ricardo da Silva Torres , Guerric le Maire

Publication : Remote Sensing

Date : 2025

Volume : 11

Issue : 3

Pages : 334

Catégorie(s)

#CIRAD #FORET Itatinga #INRAE