Résumé

Understanding the movement ecology and habitat use of freshwater fish is crucial for their conservation, with telemetry being an essential tool. Current tagging methods are restricted by the minimum body size of fish, as tags should not exceed 2% of the fish’s body mass. This limitation hinders the study of juvenile small-bodied endangered species, as the reduced fitness of tagged individuals can negatively impact their populations. This study examines the feasibility of using 12-mm PIT tags on juvenile and subadult individuals (63–90 mm fork length) of the critically endangered Rhône streber, Zingel asper. Results indicate that tagging does not significantly affect survival, growth or behavioural traits, despite the tag weight being between 2.2% and 5.4% of the fish’s weight. Tag retention was 100%, with 90% of individuals having the PIT tag fully encapsulated in the body cavity wall after 55 days. The only possible negative effect observed was a tendency, albeit statistically non-significant, for slower escape velocity in the smallest tagged individuals. These findings reduce the known minimum body size limit for 12-mm PIT tags for this species. However, the smallest individuals may be more sensitive to tagging, warranting careful consideration to avoid potential negative impacts on wild populations.

Auteurs, date et publication :

Auteurs Libor Závorka , Jean-Christophe Aymes , Alyssa Guiheneuf , Olivier Mercier , François Huger , Mickaël Bejean , Stéphane Glise , Emmanuel Huchet , Sylvie Tomanova

Publication : Knowledge & Management of Aquatic Ecosystems

Date : 2025

Issue : 425

Pages : 20

Catégorie(s)

#ECP #INRAE

Résumé

Survival rate of the larval stage is an important driver of fish recruitment. To understand mechanisms regulating larval survival it is important to understand the relative importance of abiotic and biotic factors that shape larval spatial distributions. We studied larval Coregonus distributions in surface waters (surface to 1 m) by repeatedly sampling study sites in two lakes that varied greatly in trophic state and regional climate. We evaluated the importance of bathymetric depth, Julian Day, edible zooplankton densities (EZ, ind. L 1) and wind vectors on larval spatial distributions using generalized additive modeling. In both systems, larval counts declined in a negative exponential fashion with bathymetric depth, indicating shallow depths are critical nursery habitat. The north-south wind vectors and Julian Day (which was positively correlated with surface temperature) influenced larval distributions in Lake Geneva with larval counts related to both variables linearly, whereas the east-west wind vector and EZ were unimportant. Highest larval counts were during an offshore south wind and declined slightly with Julian Day. In Lake Superior, bathymetric depth and the east-west wind vector influenced larval distributions and were unrelated to EZ, Julian Day, and the north-south wind vector. Larval counts were highest when onshore southwest winds preceded sampling. Differences in how wind affected larval distribution (offshore vs. onshore) might be related to larval size with Lake Superior larvae considerably smaller (average length 12.9 mm vs. 15.9 mm); thus, more apt to be subjected to advection. Within coastal waters, Julian Day and wind vectors influence distributions, but their importance seemingly varies lake-to-lake.

Auteurs, date et publication :

Auteurs Jamie A. Dobosenski , Daniel L. Yule , Jean Guillard , Orlane Anneville , Edmund J. Isaac , Jason D. Stockwell , Jared T. Myers , Amanda S. Ackiss , Rosaura J. Chapina , Seth A. Moore , Orlane Anneville , Chloé Goulon , Juha Karjalainen , Jean Guillard , Jared T. Myers , Jason Stockwell

Publication : International Journal of Limnology

Date : 2025

Volume : 60

Pages : 12

Catégorie(s)

#INRAE #OLA

Résumé

The exchange of energy and water fluxes between the Earth's surface and the atmosphere is crucial to a series of processes that impact human life. Noteworthy examples are agriculture yields, water availability, intensity and extent of droughts and the ability of ecosystems to provide services to society. The relevance of these processes has motivated the Satellite Application Facility on Land Surface Analysis (LSA SAF) programme to set up an operational framework to estimate—among other variables—evapotranspiration (ET) and surface energy fluxes (SEF) on the basis of observations by the Meteosat Second Generation (MSG) satellite. The LSA SAF programme has recently launched the reprocessing of the ET and SEF datasets on the basis of the most recent version of the algorithm and homogenous forcing datasets. This article features the resulting ET/SEF dataset, a Data Record that encompasses the period from the start of the operational life of the MSG satellite (2004) till 2020 and covers the field of view of the MSG satellite (i.e. Europe, Africa and Eastern South America). Details on the algorithm and the datasets driving the ET/SEF estimates are also provided as well as a quality assessment.

Auteurs, date et publication :

Auteurs J. M. Barrios , A. Arboleda , E. Dutra , I. Trigo , F. Gellens-Meulenberghs

Publication : Geoscience Data Journal

Date : 2025

Volume : 11

Issue : 4

Pages : 589-607

Catégorie(s)

#ACBB #ACBB Mons #INRAE

Résumé

Due to its short-lived progeny, including gaseous radon isotopes that can be inhaled and its significant transfer into vegetation, radium poses a substantial concern in radiation risk assessment. Although the transfer of Ra from soil to plants has been previously documented, the distribution and speciation of radium within the plant tissues, particularly within trees, remain unclear. The temporal dimension of Ra transfer is also poorly known. Therefore, the transfer of radium and others alkaline earth cations in beech trees was investigated through the analysis of fine (<2 mm) roots and leaves corresponding to tree organs with a life cycle limited to one season. This study was conducted at the experimental Montiers (INRAE-Andra site, France) and Strengbach watershed (OHGE site, France) beech-forested site. The activity of 226Ra and the isotopic ratio (228Ra/226Ra) were measured in roots and leaves using gamma spectrometry. Additionally, the concentration of alkaline earth cations (Mg, Ca, Sr, and Ba) was measured, to better constraint the mechanism of alkaline earth cation transfer through the xylem. The retention of these cations within the trees increases with the mass of the element, following the order Mg < Ca < Sr ≈ Ba < Ra, i.e.: light alkaline earth cations are more efficiently transferred from roots to leaves than heavy one. Our results suggest that these cations maintain their hydration shell during their ascent in stems and a low pH ion-exchange process rather than a complexation process with carboxylic group occurs.

Auteurs, date et publication :

Auteurs Sophie Rihs , Eric Lascar , François Chabaux , Laurent Pourcelot , Philippe Calmon , Paul-Olivier Redon , Catherine Galy , Marie-Pierre Turpault

Publication : Applied Geochemistry

Date : 2025

Volume : 165

Pages : 105938

Catégorie(s)

#FORET Montiers #INRAE

Résumé

Species Distribution Models (SDM) are useful tools providing results that can be extrapolated to anticipate species range shifts, under climate change scenarios. SDM studies integrating spatial constraints are significantly lacking in the marine environment, leading to optimistic predictions. This is particularly true for anadromous species in which marine distributions can be driven by their affinity to their natal rivers. Acipenser sturio is a critically endangered anadromous fish for which two stocked populations are currently maintained in the Gironde-Garonne-Dordogne (France) and Elbe (Germany) river systems. Benefiting from bycatch reports of A. sturio, we applied a SDM process that explicitly considers distance to home when evaluating habitat suitability. More precisely, we included the variable ‘distance to mouth of the natal river system’ into SDM inputs to test and characterize its influence on the marine distribution of A. sturio. We used this model to obtain the marine distribution under current climatic conditions with the two source populations and under population recovery scenarios (functional populations hypothesized to exist in ten currently unoccupied river systems). We projected the model under future conditions with two climatic scenarios (RCP 4.5 and 8.5) and three time slices over the 2023–2099 period. Constrained-ranges of both existing and hypothetical populations are projected to expand in the future. We observed an overall increase of habitat suitability, with new suitable sectors localized further from natal river mouths. By informing on the suitable marine surface that each hypothetical population holds and adds to the existing ones, our approach aims at informing about the feasibility of species recovery and marine habitats protection strategies. Our findings highlight the need for including dispersal information in marine SDM. The application of our dispersal-constrained approach may be considered for other less-well-known species for which dispersal point sources are identifiable, such as other diadromous species in different study areas.

Auteurs, date et publication :

Auteurs Anaïs Charbonnel , Géraldine Lassalle , Patrick Lambert , Eric Quinton , Jörn Geßner , Eric Rochard , Steve Colclough , Niels Brevé , Marie-Laure Acolas

Publication : Ecological Indicators

Date : 2025

Volume : 160

Pages : 111762

Catégorie(s)

#INRAE #XPO

Résumé

The European sturgeon (Acipenser sturio) is a critically endangered anadromous fish species with the last remaining population living in the Gironde estuary, thanks to restocking programs. Between 2010 and 2018, trawling surveys (1022 trawl tows) in the estuary caught 452 sturgeons (fork length (FL) from 25.5 cm to 154 cm). Based on previous knowledge about the species ecology, individuals have been categorized into two groups, Estuarine Dwellers (ED; FL below 68 cm) that are using mainly the estuary, and Sea Explorers (SE; FL equal or above 68 cm) that could accomplish migration at sea. ED and SE were found in the estuary at all seasons with densities being the highest in autumn for SE and in all season except spring for ED. Hotspot analyses were made at the seasonal scale to localise ED and SE concentrations. Differences were analysed according to environmental variables (temperature, water column height, salinity and concentration in suspended matters) extracted from a hydrodynamic model (MARS3D), which all contribute to fish localisation at all seasons. In all seasons, both groups were using common areas located downstream (overlap from 26 to 33%) except in autumn, when different areas were used (12% overlap). SE were encountered downstream in deeper areas with higher salinity and lower temperature (except in winter). For this group, temperature seems to be a limiting factor. ED occupied downstream as well as upstream areas with lower salinity and higher temperature in summer, but there was no habitat selection linked to simulated environmental variables in spring and autumn. Since ED are mainly using the estuary they are probably accustomed to the range of values of the abiotic variables characterising the estuary and other factors are probably at play in spring and autumn, such as prey distribution. Comparison with the location of ancient wild cohorts highlights common hotspot areas downstream with our stocked population but the disappearance of a former upstream hotspot. We explained this difference by the environmental changes witnessed by the estuarine environment in the last decades. Our results highlights important areas for both groups that could help the design of conservation measures.

Auteurs, date et publication :

Auteurs Marie Lamour , Romaric Le Barh , Marie-Line Merg , Florent Grasso , Eric Quinton , Eric Rochard , Céline Le Pichon , Marie-Laure Acolas

Publication : Estuarine, Coastal and Shelf Science

Date : 2025

Volume : 298

Pages : 108656

Catégorie(s)

#INRAE #XPO

Résumé

Extensive pesticide use for agriculture can diffusely pollute aquatic ecosystems through leaching and runoff events and has the potential to negatively affect non-target organisms. Atrazine and S-metolachlor are two widely used herbicides often detected in high concentrations in rivers that drain nearby agricultural lands. Previous studies focused on concentrationresponse exposure of algal monospecific cultures, over a short exposure period, with classical descriptors such as cell density, mortality or photosynthetic efficiency as response variables. In this study, we exposed algal biofilms (periphyton) to a concentration gradient of atrazine and S-metolachlor for 14 days. We focused on fatty acid composition as the main concentration-response descriptor, and we also measured chlorophyll a fluorescence. Results showed that atrazine increased cyanobacteria and diatom chlorophyll a fluorescence. Both herbicides caused dissimilarities in fatty acid profiles between control and high exposure concentrations, but S-metolachlor had a stronger effect than atrazine on the observed increase or reduction in saturated fatty acids (SFAs) and very long-chain fatty acids (VLCFAs), respectively. Our study demonstrates that two commonly used herbicides, atrazine and S-metolachlor, can negatively affect the taxonomic composition and fatty acid profiles of stream periphyton, thereby altering the nutritional quality of this resource for primary consumers.

Auteurs, date et publication :

Auteurs Laura Malbezin , Soizic Morin , Isabelle Lavoie

Publication : Ecotoxicology

Date : 2025

Volume : 33

Issue : 2

Pages : 190-204

Catégorie(s)

#INRAE #XPO

Résumé

Tracking the behavior of invasive alien species (IAS) is challenging due to logistical constraints that hinder high frequency surveys. Real-time automated recorders offer a promising solution, but their feasibility needs testing and validation. The acoustic camera is an efficient method to obtain real-time records of the behavior of Hemimysis anomala, a mysid that has invaded a variety of aquatic ecosystems. This approach is also a valuable tool for high-quality video recordings of mysid swarms in shallow habitats. The feasibility of this device to record the continuous behavior, including exit and entry (hereafter referred to as emergence and homing) from a shelter over a diel cycle was validated. Emergence consistently correlated with the onset of civil twilight, while homing displayed more intricate temporal trends. Homing events were longer than emergence events, but both were significantly influenced by light conditions. The termination of emergence was concomitant to the onset of the light preference as already shown by past studies. However, homing showed an earlier onset before light conditions exceeded the preference values, possibly due to inter-individual variability and/or information sharing in swarm behavior. The survey also captured the collapse in the targets number detected by the end of March, underlining the termination of the winter swarm. Furthermore, we demonstrated the importance of highfrequency temporal resolution, with a sampling frequency of at least 10-min, to accurately capture the swarm behavior. Overall, we provide original new insights characterizing H. anomala ecology and encourage the development of real-time automated recorders to track the behavior of IAS.

Auteurs, date et publication :

Auteurs Hervé Rogissart , Victor Frossard , Jean Guillard , Clément Rautureau , Stéphan Jacquet

Publication : Journal of Great Lakes Research

Date : 2025

Volume : 50

Issue : 1

Pages : 102250

Catégorie(s)

#ANR-Citation #INRAE #OLA

Résumé

The trophic niche of invasive species can vary overtime because of different processes related to ecological opportunity and invader activity that condition biological interactions with the native biodiversity. We conducted an annual-based survey of the trophic niche of the mysid Hemimysis anomala in the largest European peri-alpine lake by combining molecular and isotope analyses. We hypothesized that the population trophic niche width would vary seasonally, expanding in warm periods due to greater ecological opportunities and higher mysid metabolic activity. Molecular analyses identified a diversified set of prey throughout the year ranging from autotrophic protists to zooplankton and converged with isotope analyses to support the diet seasonality hypothesis of H. anomala with wider trophic niches and, in a lower extent, richer diets in spring and summer when compared to autumn and winter.

Auteurs, date et publication :

Auteurs Victor Frossard , Chloé Vagnon , Stéphan Jacquet

Publication : Hydrobiologia

Date : 2025

Volume : 851

Issue : 3

Pages : 487-501

Catégorie(s)

#INRAE #OLA

Résumé

Abstract

In this work, we characterised the cyanobacterial communities in the plankton and littoral biofilm of 38 lakes and in the biofilm of 21 rivers in the Alps and surrounding subalpine regions by 16S rRNA gene metabarcoding. We found little overlap in the distribution of amplicon sequence variants (ASVs) between the three habitats and between water bodies. The differences were caused by environmental filtering acting on the selection of the most abundant ASVs and a high contribution of rare oligotypes. The differentiation of community and genotype composition from specific water bodies was explained to a significant extent by environmental variables and morphometry. The taxonomic consistency of ASVs classified under the same genus name was assessed by phylogenetic analyses performed on three representative dominant genera, namely
Cyanobium
,
Tychonema
and
Planktothrix
. The analyses revealed eco-evolutionary adaptations in lakes and rivers, including some evidence for a polyphyletic nature. Monitoring individual genotypes in relation to environmental conditions will be useful to define the ecological amplitude of these taxa. However, the persistence or ephemeral nature of some of the rarest and most unusual ASVs has remained unknown.

Auteurs, date et publication :

Auteurs Nico Salmaso , Serena Bernabei , Adriano Boscaini , Camilla Capelli , Leonardo Cerasino , Isabelle Domaizon , Tina Elersek , Claudia Greco , Aleksandra Krivograd Klemenčič , Paolo Tomassetti , Rainer Kurmayer

Publication : Hydrobiologia

Date : 2025

Volume : 851

Issue : 4

Pages : 1035-1062

Catégorie(s)

#INRAE #OLA